# AC 91-16: Category II Operations - General Aviation Airplanes - Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it) - Status: Historical - Approved: August 7, 1967 - Last reviewed: October 24, 2024 - This change: Canceled by Memo signed by John Barbagallo and Richard Mathews; dated 05/21/2015. - Family: AC 91-16 - 14 CFR parts: 23, 25, 61, 91, 97, 135 - Pages: 66 - PDF: https://openairdocs.org/files/sha256/b0/14/b014d7835f621f45e95511b7afd01d822d85b91bbe83b760c4054a0c3d517b14 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C055C47D42D8419C862569E7007463F1.0001 - DRS record last changed: November 22, 2025 - Page: https://openairdocs.org/ac/91-16 ## Versions - [AC 91-16](https://openairdocs.org/ac/91-16) (Historical), approved Aug 7, 1967, 66 pages. Canceled by Memo signed by John Barbagallo and Richard Mathews; dated 05/21/2015. ## Text Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 Federal Aviation Agency Ac No: 91-16 CATEGORY .JI OPERATIONS · GENERAL AVIATION AIRPLANES ### Page 2 Federal Aviation Agency AC NO: 91-16 GENERAL OPERATING AND FLIGliT RULES EFFECTIVE : 8/7/67 SUBJECT : CATEGORY II OPERATIONS - GENERAL AVIATION AIRPLANES 1. PURPOSE. This advisory circular sets forth acceptable means by which Category II operations may be approved in accordance with FAR Parts 23, 25, 61, 91, 97 and 135. Consideration will be given to any other means the applicant may present. **2. HOW TO GET THIS PUBLICATION.** a. Order copies of this publication from: Department of Transportation Federal Aviation Administration Distribution Unit, HQ-438 Building 159 Washington, D.C. 20590 b. Identify the publication in your order as: FAA Advisory Circular AC 91-16 Category II Operations - General Aviation Airplanes Dated 1967 c. There is no charge for this publication. ### Page 3 AC 91-16 8/7/67 1. Introduction. 2. Applicability. 3 . Definitions. 4. General. 5. Evaluation Program. 6. Category II Manual. 7. Pilots. 8. Maintenance Program. Page i TABLE OF CONTENTS 1 1 1 2 3 5 6 8 ATTACHMENT 1. A B C AIRWAYS CATEGORY II MANUAL 1-58 ATTACHMENT 2. ENGINEERING EQUIPMENT INSTALLATION APPROVAL **CRITERIA AND ACCEPTABLE MEANS OF COMPLIANCE -** CATEGORY II AIRBORNE NAVIGATION, INSTRUMENT AND FLIGHT CONTROL SYSTEMS 1-7 ATTACHMENT 3. CATEGORY II APPROACH EVALUATION 1-2 ATTACHMENT 4. CATEGORY II PILOT AUTHORIZATION 1 ### Page 4 AC 91-16 8/7/67 1. INTRODUCTION. This advisory circular sets forth acceptable means by which Category II operations may be approved in accordance with FAR Parts 23, 25, 61, 91, 97 and 135. Consideration will be given to any other means the applicant may present. 2 . APPLICABILITY. This circular applies to airplanes to be used in Category II operations under Part 91. However, it does not apply to air carriers or commercial operators certificated under Part 121. 3. DEFINITIONS. As used herein, the following definitions apply . a. Category II Pilot Authorization: A part of the holder's instrument rating or airline transport pilot certificate (but separately issued) that authorizes the holder to conduct Cate­ gory II operations as pilot in command of specified types of airplanes. b. Evaluation Program: An operational program based on a series of demonstration flights to establish the capability of the flight control guidance system to perform satisfactorily in Category II operations. c. Category II ILS System: An Instrument Landing System (ILS) which provides usable guidance information from the coverage limit of the ILS to the point at which the localizer course line intersects the glide path at a height of 50 feet or less above the horizontal plane containing the ILS runway . d. Inspection and Test Program: An engineering ins'pection and test program to determine compliance with: (1) Applicable airworthiness standards set forth in regulations, technical standard orders, or other pertinent specifications approved by the Federal Aviation Administrator; or (2) military standards or a foreign government's validation found to be compatible with the appropriate Federal Aviation Regulations (FARs). ### Page 5 Page 2 AC 91-16 8/7/67 4. GENERAL. Approval for Category II operations will require regulatory compliance in three major areas. These areas are airborne equipment and systems approval, crew qualification, and the approval of a Category II manual which includes a maintenance program. Airborne equipment and sys­ tem approval may be accomplished by the airplane manufacturer or through later modifications by persons or organizations who perform this service. In some of these cases, the owner will acquire an airplane which has equipment and systems that meet the performance standards but which does not have the required Category II manual. While it is the operator's responsibility to submit the required Category II manual for approval, the actual preparation of the Category II manual may be accomplished by the airplane manufacturer, an organization or person engaged in airborne equipment and systems modifications to Category II standards, or a manu­ facturer of airborne equipment and systems. Category II manuals which originate from these or other suitable sources may be submitted by the airplane operator for approval under the same conditions as a manual prepared by the operator. A pilot in command holding a current and appro­ priate letter of authorization must also be utilized. The responsibility to meet the experience, proficiency, recency of experience, and renewal requirements for a letter of authorization rests primarily with the pilot seeking or holding such a letter. It is the responsibility of the operator (pilot in command) to utilize the services of a qualified second in command in the conduct of a Category II approach. Use of the second in command pilot is predicated on a prior determination by the pilot in command that the individual, in addition to meeting the requirements of FAR 61.3(g)(2), is also familiar with and capable of performing the second in command duties set forth in the approved Category II manual. a. Airborne Equipment and Sxstem Approval. Par. 3 (1) The primary airborne equipment and system to be approved is the flight control guidance system and, at the option of the individual or organization seeking such approval, may be accom­ plished by: (a) Type certification or supplemental type certification in accordance with the procedures and criteria set forth in Attachment 2 to this advisory circular; or (b) Completion of a satisfactory operational evaluation pro­ gram described in Appendix A to FAR 91, discussed in more detail in paragraph 5 of this advisory circular. ### Page 6 AC 91-16 Page 3 8/7/67 (2) The other instruments and equipment required by Appendix A, Section 2 of FAR 91, may be determined to be capable of performing as necessary for Category II operations during either of the programs referred to in paragraphs 4a(l)(a) or (b), above. (3) When a radio altimeter is installed for use as the primary means to establish the 100-foot decision height, it must meet the per­ formance criteria set forth in Appendix A, Section 3(c) of FAR 91 based on engineering assistance to verify compliance. b . Category II Ap£roach Procedures. Category II ILS instrument approach procedures will be issued by the Federal Aviation . Administration, and (1) Will be published in accordance with FAR Part 97, and (2) Will be made available to the public in the same manner as other published instrument approach procedures . Category II approach procedures may also be prescribed by other appropriate authority including the Armed Forces of the United States and foreign governments. 5. EVALUATION PROGRAM. The equipment to be evaluated for approval will be the flight control guidance system. This program prov ides a method of approval for those airplane owners or operators having airplanes equipped with a flight control guidance system not approved under an appropriate type or supplemental type certificate, Satisfactory completion will demonstrate that the equipment performs to the standards and with the reliability necessary for Cate gory II operations. a. The procedures and requirements for conducting an evaluation program are prescribed in FAR Part 91, Appendix A, Section 3(e) . In this regard, the following should be considered: (1) When inner marker receiving equipment i s to be used as the primary means for identification of the 100-foot decision height, its use f or evaluation approaches on a Cate gory II ILS will pose no problem when the ground equipment is installed and operable. However, in the absence of operable inner marker ground equip­ ment, it will be necessary to rely on barometric altimeters re­ quired by FAR 91, Appendix A, Section 2(a)(5) . These altimeters will be acceptable under that section if: (a) The altimeters and their static systems meet the require­ ments of FAR 91 . 170 within the past 12 months, and Par . 4 ### Page 7 Page 4 AC 91-16 8/7/67 (b) Altimeter correction data is available to the pilot in command, which considers both scale error and main landing gear wheel height of the airplane. Scale error is deter­ mined by an altilneter test and inspection under FAR Part 43 Appendix E, and the wheel height correction is necessary only if the wheel to instrument height is in excess of 10 feet presently allowed for in U. S. Weather Bureau altimeter settings provided for aircraft. For instance, a large aircraft which has a 1 9 -foot wheel to instrument height would require a 9-foot correction under this rule . Barometric altimeters meetin g (a) and (b) above are acceptable for Category II operations to establish decision heights down to 150 feet . (2) If a success rate of 90 percent is not achieved during the first 50 approaches, additional demonstration appr oache s may be con­ ducted until this rate has been reached . The demonstration approaches should be recorded on a suitable form developed by the operator in order to facilitate evaluation . (See Attachment3 for example . ) (3) Should an applicant find at any time that the evaluation program is not producing the desired degree of success, it is suggested that a careful analysis of the problem be made in coordination with the General Aviation District Office (GADO). Although the regulations appli cable to the evaluation program do not require observation of any of the approaches by an FAA inspector, experience with other evaluation programs indicat es that at least 50 percent of the approaches required by the rule should be observed . (4) The regulations do not require a pilot in command conducting an evaluation program to be a qualified applicant for a Category II pilot authorization. although many pilots participating in evaluation programs will be those ultimately issued authorizations. However, it is recommende d that only pilots meeting the experience requirements for that authorization be utilized . (5) Although it is desirabl e that at least one of the three ILS faci­ lities referred to in FAR Part 91 Appendix A, Section 3(e)(2), meet Category II criteria, it is not a regulatory requirement . (6) All evaluation approaches must be conducted under simulated IFR conditions and prior approval must be obtained from the controlling air traffic control (ATC) facility. In requesting approval, identify the approach as an "evaluation approach." (7) The evaluation program should be utilized to help develop and establish appropriate operati onal procedures and techniques for inclusion in the Category II manual. ### Page 8 AC 91-16 Page 5 8/7/67 (8) Displays associated with normal and abnormal functioning of the flight control guidance system should be evaluated to determine if they provide the crew with information suitable for Category II operation. (9) Other system or equipment rev~s1ons should be made where needed to remove limitations which are not compatible with Category II operations. Operators now possessing airplanes equipped with autopilot installations should be aware that altitude loss data in the approach configuration now contained in the approved airplane flight manual may preclude operations to a 100-foot decision height. Advisory Circular No. 23.1329-1, Automatic Pilot Systems Approval (Non-Transport), and Advisory Circular No. 25.1329-1, Automatic Pilot Systems Approval (Transport), set forth an acceptable means by which automatic pilot instal­ lations may meet the requirements of FARs 23 and 25 respectively. b. Airplanes will be approved to engage in Category II operations when: (1) A satisfactory evaluation program has been completed, and (2) A suitable Category II manual, including a maintenance program, has been submitted and approved. **6. CATEGORY II MANUAL.** a. Category II operations involve the airplane owner or operator, the maintenance personnel and facilities, and the flight crews. Each has certain responsibiliti es to others involved as well as his own indi­ vidual responsibility. FAR 91.34(a) specifies that no person may operate without an approved Category II manual for the aircraft. b. The purpose of the Category II manual is to set forth in a single document basic responsibilities, limitations, operational procedures, maintenance programs and related instructions. To assist applicants in the preparation of a Category II manual, Attachment 1 has been prepared as a guide in format and content subject to revision by the applicant as appropriate to the specific equipment and procedures intended to be employed in Category II operations. c. To receive formal approval, the Category II manual must contain that information specified in FAR 91, Appendix A, Section l(b), and must be submitted in accordance with the instructions provided in Section l(a) of Appendix A of FAR 91. Operators of turbojet aircraft shouldprovide in the operating instruction portion of the approved Category II manual minimum runway length for use at the destination airport. The agency has issued Advisory Circular No. 91-10, Suggestions for use of ILS Minima by Gene ral Aviation Operators of Turbojet Aircraft . This Circular may be used as reference for prep­ aration of the manual material, or, if the operator desires, be in­ corporated as Category II manual material in the operating instruction section .of the manual. Par 5 ### Page 9 Page 6 AC 91-16 8/7/67 d. The regulations under which Category II airborne equipment and systems are approved and authorized for use are silent on the transfer of ownership of the airplane in which the equipment is installed. The authorization to conduct Category II operations by the new owner does not require reapplication or reapproval of the airborne equipment or systems and is only contingent upon compliance with the applicable regulations and the procedures, 11mitations and maintenance program set forth in the approved Category II manual for the airplane involved. It follows that the airplane purchaser should arrange for transfer of the approved Category II manual with the airplane . Prior to engaging in Category II operations, the new owner should review the approved Category II manual to determine if the content of the manual, including the maintenance program, is compatible with his capabilities and operational requirements. In the event the Category II manual requires revision, those which are necessary or desirable should be submitted for approval to the General Aviation District Offi ce in whose area the airplane is based. **7. PILOTS.** a. Pilots complying with the experience and skill requirements of Federal Aviation Regulations 61.36 and 61.37A respectively will be authorized to conduct Category II operations. Since they will not receive a new certificate or rating, applicants for a Category II pilot authorization are not required to comply with FAR 61.21 which establishes prerequisites for certain examinations and tests. b. Category II Pilot Authorizations - Application. (1) FAA Form 342, or FAA Form 8460-l if available, will be used for pilot applications and submitted to the General Aviation District Office appropriate to the pilot's base of operation or con­ venient to the location of ·the airplane to be utilized for the oral operational test and practical test. (2) It will be necessary to present at the time of application a pilot logbook to establish compliance with the experience requirements of FAR 61.36. c. Category II Pilot Authorizations - Skill Requirements. Par 6 (1) At the time of the oral and practical tests, it will be necessary to have available for use an airplane for which a Category II manual has been approved, and which otherwise meets the operating requirements of FAR Part 91 for Category II operations. (2) The approved Category II manual for the airplane to be flown will be used in conducting both the oral and practi cal tests. ### Page 10 AC 91-16 Page 7 8/7/67 (3) As a part of the practical test, the applicant will be asked to demonstrate his ability to determine that the duties assigned to the second in command are satisfactorily performed. For neces­ sary reasons associated with testing the applicant's ability to perform the maneuvers required for the fl~ht test, the applicant of course, must perform the maneuvers. This procedure may be contrary to the duties assigned to the second in command in the Category II manual. For this reason, we wish to make it clear that the manner in which the flight test must be conducted does not in any way indicate a position by the FAA as to the proper allocation of duties that are otherwise assigned to the second in command. It should be understood that the pilot serving as second in command during the practical test for the pilot in command must hold an appropriate class rating and, in the case of a large airplane or a small turbojet airplane, a type rating for that airplane. (4) During Phase I, Oral Operational Test, the pilot in command will be expected to demonstrate a satisfactory level of knowledge with respect to those items specified in FAR 61.37A(~(l). Particular emphasis will be placed on a knowledge of the procedures, instruc­ tions and lUnitations set forth in the approved Category II manual required by FAR 91.34(a)(l). (5) The flight maneuvers and the manner in which they are to be performed are described in FAR 61.37 A and (c) (2). Applicants may employ any suitable hooded device that will effectively prevent outside visual reference during the flight test maneuvers. d. Category II Pilot Authorization - Issuance 2 Limitations and Renewal. (1) Issuance. A Category II pilot authorizationwill identify the following: (a) The airplane, by tYPe, for which the authorization is valid. (Large airplanes by type are listed in Advisory Circular No. 61-1 (current issue). Small airplanes manufactured under the same type certificate issued the airplane manufacturer may be considered as being the same basic type for purposes of issuance or renewal.) and (b) The holder by name, type of certificates and date of issue. NOTE: See Attachment 4, Example of Category II Pilot Authorization. Par 7 ### Page 11 Page 8 AC 91-16 8/7/67 (2) Limitations. Upon original issue, the authorization will contain a limitation for Category II operations of 1600 feet RVR and a 150-foot decision height. This may be removed when the holder shows that he has made three Category II ILS approaches to a landing under actual or simulated instrument conditions with a 150-foot decision height since the beginning of the 6th preceding calendar month. (3) Renewal. Renewal of a Category II pilot authorization may be accomplished by passing the practical test prescribed in FAR 61.3 7 A at any time, in accordance with the renewal pro­ visions of FAR 61.10. To retain semi-amual continuity, it may be renewed during the calender month in which it would expire or during the preceding calendar month . NOTE: The regulations, specifically those relating to the maintenance program set forth in the approved Category II manual, allow substitution for each alternate inspectio~ of a functional · flight check conducted by a pilot holding Category II authorization for the type airplane being checked. When this procedure is employed, the pilot should be familiar with that portion of the maintenance program to the extent that the funct ional flight check is conducted in accordance with the instructions and procedures contained in the approved Category II manual, and the results entered in the maintenance records. The regulations also require any discontinued Cate ­ gory II approach resulting from a malfunction of any Category II instrument or item of equipment to be entered in the maintenance records. 8. MAINTENANCE PROGRAM. Each applicant for Category II authorization submits for approval a maintenance program for installed Category II instruments and items of equipment which is to be included in the Category II manual of each airplane to be maintained under that program. The overall objec­ tive of a Category II maintenance program is to assure that the oper a tor has considered all special maintenance requirements imposed by the opera­ tions to lower minimums, has geared his organization or operation to cope with them, and has documented them in his appl icati on. An acceptable program should contain a means of assuring that the required instru­ ments and items of equipment can reasonably be expected to continue to operate at the level of performance upon which Category II approval is based. Attachment 1, Sections IV throu gh VIII, contain general guidance material which may be used to develop the maintenance program portion of Par 7 a Category II manual. The material should not be considered a complete program, but only a means of assistance in the preparation of a program. Reference will be made to various pages of Attachment 1 in the followin g paragraphs . The notes on those pages are additional information and not a part of the examples shown. Where typical examples of equipment lists, records of bench checks prior to application , inspections, flight checks, bench check schedules, etc., are shown in Attachment 1, Sections IV through VIII, they are to be considered only as guidance in preparing the maintenan ce program . ### Page 12 AC 91-16 Page 9 8/7/67 a. Aircraft Ele ctrical Capacity . In developing a Category II equipment and maintenance program, consideration should be given to the capacity of the airplane's electrical generating system. The system should be capable of supplying electrical power to all required instruments and items of equipment during Category II operations without limits on the applied electrical load. b. Instruments and Equipment Approval. Before presenting an airplane for approval of the instruments and equipment, it must be shown that, since the beginning of the 12th calendar month before the date of submission, the equipment required in FAR 91, Appendix A, Section 2(a), has been bench checked, tested, or inspected according to the standards and methods contained in FAR 91, Appendix A, Section 3. A list of installed Category II instruments and items of equipment, including make and model of thos e specified in FAR 91, Appendix A, Section 2(a), must be included in the Category II manual. A means of submitting this information is shown in Attachment 1, Section IV, pages 24 and 25. These pages also show that the static pressure syst em was tested and inspected since the beginning of the 12th calendar month before the airplane is presented f or approval of instruments and items of equipment. c. Maintenance Schedule. Category II instrum ents and items of equ ipment are divided into Groups I and II (FAR 91, Appendix A, Section 2) acc ording to maintenance requirem ent s. Those listed in Group I r equire bench checks within 12 calendar months a ft er the date of the previous bench check. Group II instruments and equipment with the exception of the stati c system do not require special maint enanc e procedures oth er than those nece ssary to retain the original approval condition. A typical sche dule for insp ections, flight checks, and bench che cks is shown i n Attachment 1, Section V, page 31. d. Inspections. An inspection is to be performe d on each Group I item of equipment within three calendar months of the previous insp e ction using procedures contain e d in the approve d maintenan ce program. Inspection procedures should be shown adequate to det ermine that the equipment as install ed will perform as appr oved for Category II operat i ons. Se lf-test f eatures may be submitted for approval. Instructions for their use and interpretation of self-test indications should be contai ned in the maint enance program. Inspe ctions are per­ formed by a person authorized by FAR Part 43, except that a functional flight check may be substituted for each alternate inspection and is performed by a pilot holding a current Cat egory II pilot authorization for the type airplan e being checked. In addition to performing the functional flight checks of Group I equipment, the pilot should check any other equipment capable of being tested in fli ght . Typical inspections and functional flight check procedures are shown in Attachment 1, Sections VI and VII. Par 8 ### Page 13 Page 10 AC 91-16 8/7/67 e. Bench Checks. Maintenance standards, practices, and limitations established in obtaining original equipment approval may be used for initial bench check and inspection standards. If it is determined later that these standards and practices will not main tain the equip­ ment to Category II approval performance standards, t he operator should establish additional tests, inspections and checks, more rig id calibration procedures and tolerances, etc., in order to retain these performance standards. All such changes which alter the approved main­ tenance program must be approved by the Federal Aviation Administrator. Typical bench check procedures are shown in Attachment 1, Section VIII. The equipment manufacturer's maintenance procedures may be incorpor­ ated in the bench check portion of the program by reference to the manufacturer's manual title and number if those procedures are found adequate to maintain the ability of the equipment to perform as appr oved for Category II operations. If exceptions to the manufacturer's main­ tenance procedures are required to meet Category II perf ormance stan­ dards, they should be indicated as such in the maintenan ce program. An example is shown in the bench check procedure for the Ajax Node! 22-G glide slope receiver in Attachment 1, Section VIII, page 55. f. Altimeter and Static System. If the 12-month altimeter bench check and static system test and inspection is entered in the airplane maintenance records, the requirements of FAR 91.170 will be met. g. VOR Receivers. If the VOR receiving system(s) are included in the approv ed maintenance program, the requirements of FAR 91.25(a)(l) will be met. h. Repairs . The Category II manual should contain a procedure for assuring that repairs performed on listed instruments and items of equipment will return the equipment t o at least its original Category II approval condition before the airplane is used for Category II operations. The procedure should include a positive means to noti fy the pilot in command when a listed instrument or item of equipment has not been so repair ed. Examples of such for ms and pr ocedu res have not been includ ed in Attachment 1, Sectio n V, because such procedures will have to conform to particular company organization. i. Replacement. The Category II manual should contai n a procedure to assure that equipment replaced with the same make, model, and design will provide system performance at least equal to Category II approval condition. j . Alterations. All alterations to equipment that is requ i red by FAR 91, Appendix A, Section 2, are approved by the FAA under the provisions of Secti on 3(b), (c), and (d) of that Appendix. Par. 8 ### Page 14 AC 91-16 8/7/67 k. Records. All tests, inspections, and bench checks performed on required equipment should be entered in the maintenance records required by FAR 43.9. Functional flight checks, although perform ed by pilots, must also be entered in the maintenance records in accord· ance with FAR 91, Appendix A, Section 4(a)(5) . A separate record form for each item of equipment may be used if de s ired. Maintenance performed on this equipment at other than scheduled intervals must also be entered in the airplane maintenance records. In addition, an entry in the maintenance records is required showing the date, airport and reason for each discontinued Category II approach because of a malfunction of a listed instrument or item of equipment. Such forms could also be used to record instrument and equipment malfunc­ tions and failures occurring at times other than Category II opera­ tions if a means is provided to identify malfunctions occurring during Category II approaches. A method of recording scheduled inspections and bench checks, and discontinued Category II approaches is shown on pages 32 and 33of Attachment 1, Section V. Space has been provided to identify the malfunctioning equipment and a description of the malfunction . 1. Maintenance Period Extensions. Operators may apply for extension of check, test and inspection periods after one 12-calendar-month maintenance cycle has been completed. In order to justify the extension, equipment performance and service history should show that the extension will not adversely affect the required level of per­ formance of the Category II instruments and equipment. Application for extensions should be made by letter to the General Aviation District Offi ce having jurisdiction of the area in which the operator is located. The following data should be made available: (1) The currently approved maintenance program. (2) Records of Category II approaches discontinued due to malfunctionin g equipment. (3) Number of actual and stmulated Category II approaches completed during the past maintenance cycle, if available. (4) Maintenance records of Category II equipment failures. (5) Service history of known trends toward malfunctioning. (6) Unit mean flight time between failures. (7) Records of functional flight checks. Par 8 ### Page 15 Page 12 AC 91-16 8/7 / 67 m. Time Increase. Equipment performance and reliability, as determined by evaluation of the data submitted with the application for exten­ sion, will be major factors in determining the amount of maintenance period extension to be granted. Extension periods in most cases would be one calendar month for inspections and functional flight checks and four calendar months for bench checks. Attachments -4 ### Page 16 AC 91-16 8/7/67 A B C AIR~.JAYS CATEGORY II 'iANUAL Attac h me nt 1 Page 1 (and 2) ### Page 17 AC 91-16 8/7/67 FOREWORD Att achment 1 Page 3 (and 4) This Category II manual outline has been prepared as guidance material to assist in the preparation of the Category II manual required by FAR 91.34. This manual, when approved by the FAA, completes one condition for the conduct of Category II operations. Compliance with its contents as approved is also required in order to conduct such operations. Sections I through III provide for a statement of the applicability of the manual, the procedures and instructions for use of the CAT II airborne equip­ ment and a description of the airborne systems and equipment.* Sections IV through VIII provide a partial example of a maintenance program designed to set forth the methods and procedures for maintaining and checking the Category II airborne equipment. The guidance material contained herein does not preclude the development of Category II manuals by aircraft manufacturers, equipment manufacturers or those engaged in the installation and/or modifications of airborne equipment and systems intended for use in Category II operations. *NOTE: Although not a manual requirement, operators may, if they desire, provide for copies of pilots' Category II letters of authorization as an item of content in the Category II manual. ### Page 18 AC 91-16 8/7/67 Sect i on I APPLICABILITY Attachment 1 Page 5 (and 6) ### Page 19 AC 91-16 8/7/67 Section I - Applicability Attachment 1 Page 7 (and 8) The Category II manual is required for the operation and maintenance of the listed Category II airplane and its instruments and equip ment identified below. It must be available in the airplane at all times f or use by the crew and to all persons performing maintenance on the listed Category II equipment . An additional copy must be kept at the principal operati ons base and each copy must be kept current. Each page has been separately i dentified and approve d by the Administrator.* No changes shall be made wi thout the approval of the FAA Administrator except that additional copies of currently approved forms may be added. The airplane to which this manual applies may be used to conduct Cat ego ry II operations provided the instruments and items of equipme nt liste d herein that are required for a particular Categ ory II operati on are : 1. Approved under Section 3 of Appendix A to FAR 91, and 2 . Inspected and maintained in accordance with the approved mai ntenance program contained herein . Aircraft Nl234 Beech B-55 S/N ~ * Date Inspector's Signature : GADO (Identification): ### Page 20 AC 91-16 8/7/67 Section II OPERATING INSTRUCTIONS Attachment 1 Page 9 (and 10) ### Page 21 AC 91-16 8/7/67 Section II - Operating Instructions Attachment 1 Page 11 1. GENERAL. Statement concerning basic flight control guidance system or systems to be employed during Category II operation, such as a flight director system only or approach coupler system only or both systems when installed and approved for use. 2. CATEGORY II AIRBORNE EQUIPMENT - DESCRIPTION. Describe in this section of the Category II manual the operational characteristics, capabilities and limitations appropriate to the airborne Category II installed equipment: a. The flight director system, b. The automatic approach coupler (if applicable), c. The approved system used to identify the decision height, d. The instrumentation and display systems, e. Automatic throttle control systems (if applicable), f. Other systems and/or devices peculiar to the particular instal­ lation; i.e., computed go-around guidance equipment. 3. OPERATIONAL PROCEDURES AND INSTRUCTIONS - GENERAL. Set forth procedures and instructions developed by the operator to be used and adhered to by the crews which should include the following: a. A procedure for determining the minimum runway length for use at destination airports (turbojet aircraft only). b . Approach monitoring. Crewmember duties during a Category II approach should be clearly delineated. c. Functional testing of the radar (radio) altimeter. d. Resolution of the decision height. If operation is predicated on · the use of barometric altimeters, the errors determined to exist in the altimeter system, including correction for wheel height, are to be applied to the indicated altitude. e. Use of RVR information. f. Decision region . The region between the middle marker and the 100-foot point where the pilot must decide to either continue his approach or execute a go-around. Instructions to pilots should include the maximum raw ILS deviation which will permit a safe landing. ### Page 22 Attachment 1 Page 12 AC 91-16 8/7/67 g . Missed approach procedure. Crewmember duties during a missed approach should be clearly delineated in the Category II manual. h. Use of airborne low approach equipment including cross-over switching system, if provided for. i. Instrument failure warning system 4. PROCEDURES FOR MANUAL APPROACH - FLIGHT DIRECTOR. Describe the proce­ dures to be employed in the use of this equipment with respect to: a . Mode selector(pilot and second in command). b. Tuning of navigational receivers . c . Course indicator check . d. Course selection. e. Pitch attitude setting. f. Altitude hold. g. Radio altimeter self-test (if appropriate). h. Radio altimeter minimum altitude warning light and use of minimum decision altitude index (if appropriate). 5. PROCEDURES WHEN CLEARED FOR AN APPROACH WITH RESPECT TO: a. Pilot-in-command's mode selector (heading to approach). b . Second-in-command's mode selector (when appropriate). c. Capture of localizer . d . Capture of glide path. e. Response of glide slope pointer approaching outer marker. f. Glide slope capture indication and, if appropriate, appearance of runway symbol and status of pitch commands and V-bar commands. g. Selection of missed approach heading and go-around pitch command. Par . 2 ### Page 23 AC 91-16 8/7/67 Attachment 1 Page 13 (and 14) h. Pilot-in-command and second-in-command flight director indicators, cross check for steering command and navigation displacement agreement. i. Pilot-in-command and second-in-command duties and procedures as they relate to: (1) Approach configuration of the airplane from outer marker to touchdown. (2) Altitude and airspeed callout. (3) Check for visual contact (specific phraseology). (4) Indicating ground or lights. j. Glide slope extension (if applicable). k. Visual contact at 100 feet (second in command). 6. AUTOPILOT APPROACH. The same basic stabilized approach procedures should be established for the use of a coupled Category II approach as those employed for a manual approach. NOTE: If the performance of the auto­ coupler dictates a lesser flap setting. the pilot should not be required to upset the stabilized approach by making a configuration change to landing flaps during the approach. 7. MISSED APPROACH. Procedures and instruction regarding the use of the airborne equipment during the execution of a missed approach. 8. E}ffiRGENCY OPERATION - WARNING FLAGS. A brief description of the purpose and function of the following warning flags: a. Glide slope flag. b. VOR/LOC flag. c. Compass flag. d. Computer flag. e. Radio altimeter flag. Par. 5 ### Page 24 AC 91-16 8/7/67 Section III FLIGHT CONTROL SYSTEM DESCRIPTION Attachment 1 Page 15 (and 16) ### Page 25 AC 91-16 8/7/67 Attachment 1 Page 17 Section III - Flight Control Guidance System Description 1. GENERAL DESCRIPTION. This section is intended to provide for the flight crew a description of the flight control guidance system and the purpose it serves, first, as a total system with respect to both crewmembers, and second, as a partial or separate system to be utilized by each pilot flight control system. This section of the manual should, for example, describe the pilot-in-command's flight control system and that of the second in command explaining: a. Similarity and/or differences of systems. b. Integration of autopilot and flight director systems (when appropriate). c . Mode selection for each or both systems . d. Data source for each system. 2. EQUIPMENT COMPONENT DESCRIPTION. Automatic flight contr ol systems usually provide their services through the interconnection of vari ous equipment. Such a system may contain several or all of the f ollowin g units which should be briefly described as to basic function: a. Emergency disconnect. b. Rate gyro . c. Primary servo. d. Trim coupler. e. Sensing unit. f. Autopilot amplifier, g . Altitude controller. h . Airspeed sensor . i. Pedestal controller. j. Flight computer. k. Instrument amplifier . Par . 1 ### Page 26 Attachment 1 Page 18 (thru 20) AC 91-16 8/7/67 3. WARNING SYSTEMS. The detection and warning system, its purp ose and limi­ tations associated with the flight control system, should be described and may include: a . Objective of the display and monitor warning system . b . Location . c . Comparison warning monitor (if provided). d . Basic data source displays. e . Data sour ce comparison displays . f. Warning flags and data source comparison. g. Crew cross-check comparisons. h. Specific failures which may activate the warning flags for a parti­ cular system or equipment should be listed. As a typical example, in the case of some flight director systems, the steering computer flag monitors the following: (1) Flight director AC power . (2) Flight director DC power . In the case of a slightly different basic flight director system, the steering computer flag monitors: (1) Gyro mode, voltage and attitude power. (2) Heading mode, power and attitude . (3) NAV/LOC mode, attitude, heading power and VOR/ LOC flag voltage . (4) Approach mode (low) attitude and heading power, LOC and GS flag voltage. It is highly desirable that this section of the manual contain func­ tional block diagrams of the warning displays available t o the crew and the warning data source . Data available from the equipment manu­ facturers appropriate for use in this or any other section of the Category II manual may be utilized. 4. LIST OF APPROVED CATEGORY II EQUIPMENT. This list of approved equipment is required as a part of the contents of the maintenance program portion of the Category II manual and, for the purpose of manual approval, need not be listed elsewhere unless the operator wishes to do so. However, if a list is provided in the operations portion, the required list contained in the maintenance program will be the controlling document in the event of any discrepancies between the two lists. Par . 3 ### Page 27 AC 91-16 8/7/67 Section IV MAINTENANCE PR(X;RAM - GENERAL Attachment 1 Page 21 (and 22) ### Page 28 AC 91-16 8/7/67 MAINTENANCE TERMINOLOGY Attachment l Page 23 The term "inspection 11 as used in this program means inspection conducted by a qualified certificated mechanic or a repair station, using the manufacturer's recommended test equipment, or the equivalent, to check Category II instru­ ments and items of equipment as installed in the airplane. The term nfunCtional flight check 11 means a check conducted by a pilot.holding a current Category II pilot authorization for the type airplane being checked. The term "bench check 11 means removal of an instrument or item of equipment from the airplane for: a. A visual inspection for cleanliness, impending failure, need for lubrication, repair or replacement of parts, b. Correction of deficiencies found, and c. Calibration to at least the specifications and standards contained in the "Schedule of Inspections and Bench Checks" in this manual. ### Page 29 Attachment 1 LIST OF INSTALLED CATEGORY II EQUIPMENT Aircraft Nl234 - B-55, Beech Baron, S/N 4255 EQUIPMENT ITEM Group I Localizer receivers Glide slope receiver Glide slope receiver Marker receiver Barometric altimeters Flight director Airspeed indicators (Add additional required Group I items.) Group II Failure warning systems Rain removal equipment (Add additional required Group II items.) MAKE MODEL AJAX 16L AJAX 22G ARGO GS33 VOLE AV-21 OLSMAN 399-BZ GAINS 263-B ZIPCO 16283 AC 91-16 8/7/67 **APPROVAL METHOD USED T.C.** T.C. T.C. Evaluation Evaluation S.T.C. T.c. Evaluation Evaluation NOTE: Where more than one instrument or item of equipment is required by FAR 91, Appendix A, Section 2, and different makes and models are installed in the pilot and second-in-command positions, each make and model should be listed. ### Page 30 **RECORD OF PRIOR 12 HONTHS BENCH CHECKS. TESTS, AND INSPECTIONS** ITEM MODEL CHECKED MAKE BY STANDARDS DATE Localizer Receivers AJAX 16L Air Services Co. RTCA Paper 10/6/66 Cert. No. 6283 23~63/D0-117 Columbus, Ohio Glide Slope Receiver AJAX 22G " RTCA Paper 10/6/66 23-63/00~117 Glide Slope Receiver ARCO GS~33 II II " Bare. Altimeters OLSMAN 399-B2 " FAR 43, Appendix E 9/3/66 Comm. Transceiver ARCO KM12 II Mfrs. !>1aint. 10/6/66 Manual 11863-25Nl Flight Director GAINS 263-B rr Nfr s. Maint. 11/10/66 Manual 41FD-263-B Marker Receiver VOLE AV-21 II Mfrs. Maint. ~0/6/66 Manual lf334-21 Static Pressure --- --- rr FAR 43 9/3/66 System(s) Appendix E Copies of work orders and maintenance releases are available. ### Page 31 AC 91-16 8/7/67 Section IV MAINTENANCE PROGRAM - GENERAL Attachment 1 Page 27 1. The specifications and procedures contained herein are intended to assure that the condition of the listed Category II equipment on which maintenance is performed is at least equal to its Category II approval condition before it is returned to service for Category II operations. 2. All defects and malfunctions of listed Category II equipment will be entered in the airplane maintenance records . Prior to conducting Category II operations, the pilot will determine, by review of - these records, that all defects and malfunctions have been corrected and all required equip­ ment has been returned to its Category II approval condition. 3. All tests, inspections, and bench checks will be performed at the intervals specified in the Category II maintenance schedule shown on page 31. Any change to that schedule must be approved by the FAA. 4. Bench checks of Category II instruments and items of equipment will be performed only by appropriately rated repair stations in accordance with the procedures and instructions contained in the bench check procedure section of this manual. 5. A work checksheet will be completed for all bench checks to assure that all required inspections, tests, and calibrations have been made. This worksheet will be filed in the permanent maintenance records of the airplane. Such a worksheet is shown on page 53 of this manual. 6. Inspections will be conducted using the procedures on the appropriate inspection sheet (see pages 37 - 42 of this manual) to test instruments and items of equipment while installed in the airplane. Where special test equipment is not specified for the performance of the inspection (communications equipment, etc.), manufacturers' instructions or accepted industry practices for operational testing will be used to determine that the equipment will perform as approved for Category II operation. Defec­ tive, out of tolerance, or malfunctioning equipment will be removed from the airplane for bench check, repair, and calibration and returned to Category II approval condition. 7. A functional flight check by a pilot holding a current Category II pilot authorization for this type airplane may be substituted for each alternate inspection. 8. The altimeter will be removed from the airplane and taken to a Class 1 instrument or a limited class instrument repair station appropriate to the altimeter make and model for bench check and calibration within 12 calendar months of the previous bench check. Par. 1 ### Page 32 Attac hment 1 AC 91-16 8/7/67 9. An entry will be made on the Equipment Inspection and Bench Check Record, Form ABC-102, page 32 of this manual, for each inspection and bench check of an item of equipment. Functional flight checks performed by a pilot will be entered on this same form. All data sp~ces on the form will be completed. Individual Forms ABC-102 will be used for each listed item of equipment. 10. Entries will be made on Form ABC-101, page 33 of this manual, showing the date, airport, and reason for each discontinued Category II operation because of malfunction of a listed instrument or item of equipment. The entry will identify the instrument or item of equipment that malfunctioned and include a description of the malfunction. 11 . All alterations to required instruments and items of equipment listed on page 24 must be approved by the FAA before the equipment is used in Category II operations . 12. When equipment listed on page 24 is replaced with the same make, model and design, the replacement equipment will be inspected and bench checked using the standards and procedures contained in this program to assure performance at least equal to Category II approval standards. 13. Changes to make, model or design of any components of the flight control guidance system must be approved as installed under applicable type or supplemental type certification procedures or by an FAA evaluation program. Par. 9 ### Page 33 AC 91-16 8/7/67 Section V MAINTENANCE - SCHEDULE AND RECCE.DS Attachment 1 Page 29 (and 30) ### Page 34 SCHEDULE OF INSPECTION AND BENCH CHECKS Aircraft Nl234 - Category II Instruments and Items of Equipment ITEM MAKE MODEL INSPECTION BENCH CALIBRATION CHECK SPECS. Group I Localizer Receivers AJAX 16L Qtrly 12 mo. RTCA Paper 23-63/D0-117 Glide Slope ~eceiver AJAX 22G Qtrly 12 mo. See page 55 of this manual Glide Slope Receiver ARCO GS33 Qtrly 12 mo. RTCA Paper 23-63/D0-117 Marker Receiver VOLE AV-21 Qtr1y 12 mo. Mfr. Manual 334-21 Barometric Altimeters OLSMAN 399-B2 Qtrly 12 mo. FAR 43, Appendix E Flight Director GAINS 263-B Qtrly 12 mo. Mfr. Manual FD-263-B Airspeed Indicators ZIPCO 16283 Qtrly 12 mo. Mfr. Manual A-283 (Add additional required Group I items) Group II Static Systems Test and inspect each 12 months to FAR 43, Appendix E standards. NOTE: Where more than one instrument or item of equipment is required by FAR 91, Appendix A, Section 2, and different makes or models are installed in the pilot and secondwin-command positions, each make and model should be listed in the above schedule. FORM ABC-104 co> -n ..... -..c Q'\ ..... . … I ..... Q'\ ### Page 35 Attachment 1 Page 32 AC 91-16 8/7/67 CATEGORY II EQUIPMENT INSPECTION AND BENCH CHECK RECORD A/C reg. no. Nl234 HFR. & MODEL Beech B-55 S/N_~56~7:...:8::.:Y:-:------- ITEH Marker Receiver MFR. & MODEL VOLE AV-21 S/N 2A-436 --~~~------------INSPECTION PERIOD 3 months BENCH CHECK PERIOD 12 months INSPECTION & HAINTENANCE SPECIFICATIONS USED VOLE AV-21 Haint. Hanual 1!334-21 **I NSPECTIONS** DATE AGENCY OR PERSON LOCATION TECHNICIAN PERFORNED PERFOHMING OR PILOT 6/6/66 Aero Services Inc. Cincinnati o. Technician 9/6/6 6 Q. o. Smith Cleveland 0. Pilot in Cornm. BENCH CHECKS DATE REPAIR STATION OR TECHNICIAN PERFORI-fED FACILITY PERFOHHI NG 12/4,'66 Aer o Ser vice, I nc .. Cincinnati Ohio ~f2 37 Robt. J ones FORH ABC-102 ### Page 36 AC 91-16 8/7/67 Attachment 1 Page 33 (and 34) DISCONTINUED CATEGORY II APPROACHES AND EQUIPMENT MALFUNCTION RECORD Position Legend: Pilot - ifFl Second in command - #2 DATE AIRPORT A/C REG. MALFUNCTION ITEM DESCRIPTION OF NO. MALFUNCTION 9/2/65 JFK Nl234 Glide Slope recvr. #1 Showed flag at OM. 9/10/65 JFK N1234 Barometric altimeters Readings did not 1/10/66 ORD N1234 agree. Flight director No LOC command • . Form Al3C-l01 ### Page 37 AC 91-16 8/7/67 Section VI TECHNICIAN-CONDUCTED INSPECTIONS Attachment 1 Page 35 (and 36) ### Page 38 AC 91-16 . 8/7/67 GLIDE SLOPE RECEIVER SYSTEM INSPECTION AJAX MODEL 22-G Attachment 1 Page 37 The following inspection will be conducted on both glide slope receiving systems at the intervals specified in the "Schedule of Inspection and Bench Checks" contained in this manual. The inspection will be accomplished by a qualified certificated mechanic or a repair station, using ramp test equip­ ment which will perform the tests listed in Paragraphs 1, 2 and 3. The flight director system must be turned on and set to GS MAN while performing these tests, because glide slope information is displayed on the flight director course indicator. Following the test equipment manufacturer's instructions, perform the following sequence of tests: 1. Position the ramp test equipment at the:proper distance from the airplane and radiate a standard glide slope test signal on the desired frequency of a sufficient strength to move the glide slope indicator flag alarm to the "out of sight" position. 2. Test for correct glide slope indicator deflection, full scale up and down and centering. 3. Test for correct flag alarm sensing and deflection and confirm that the alarm indicator is displayed during loss of either the 90 or 150 cps mod­ ulation, or reduction of both signals to one-half the normal 40 percent. 4. If possible, determine if any noise or interference is present which would cause erratic indications by running the engine(s) to check for ignition, electrical motor, or generator noise, and channel other receivers and transmitters to determinethat interaction is not taking place. 5. Make a thorough visual inspection of both receiving installations for physical security, electrical cable connections, condition of antenna, etc. 6. Enter the date, name of the agency or person conducting the inspection, indicate satisfactory or unsatisfactory performance in the maintenance record of the glide slope receivers . The above inspection will also be made after the repair or replacement of any component of the glide slope receiving systems. ### Page 39 Attachment 1 LOCALIZER RECEIVER SYSTEM INSPECTION AJAX MODEL 161 The following inspection will be conducted on both localizer receiving sys­ tems at the intervals specified in the "Schedule of Inspection and Bench Checks 11 contained in this manual. The inspection will be accomplished by a qualified certificated mechanic or a repair station, using ramp test equip­ ment which will perform the tests listed in paragraphs 1, 2 and 3. The flight directox · system must be turned on and set to GS MAN while performing these tests, because localizer deflection is displayed on the flight director course indicat or. Following the test equipment manufacturer's instructions, perform the follow­ ing sequence of tests: 1. Position the ramp test equipment in the proper location from the airplane and radiate a standard localizer test signal on the desired frequency of a sufficient strength to move the localizer flag alarm to the "out of sight" position. 2. Test for c orrect localizer indicator deflection, full scale to left and right and centering. 3. Test for correct flag alarm sensing and deflection and confirm that the alarm indicator is displayed during loss of either the 90 or 150 cps modulation, or reduction of both signals to one-half the nor mal 20 percent. 4. Channel the receiver to all navigational facilities which may be received at the test l vcation, and confirm that the selector dial indicates the correct frequency. 5. Test the receiver audio outputs for satisfactory level, proper rotation and absence of noise in level control and selector switches when operated. 6. If possible, determine if any noise or interference is present by running the engine(s) to check for ignition, electrical motors, or generator noise, and channel other receivers and transmitters to determine that interaction is not taking place. 7. Make a thorou gh visual inspection of both receiving installations for physical security, electrical cable connections, condition of antenna, etc. 8. Enter the date, name of the agency or person conducting the inspection, indicate satisfactory or unsatisfactory performance in the maintenance record of the localizer receivers. The above inspection will also be made after the repair or replacement of any component of We localizer receiving systems . ### Page 40 AC 91-16 8/7/67 MARKER BEACON RECEIVER SYSTEH INSPECTION VOLE MODEL AV-21 Attachment 1 Page 39 The following inspection will be conducted on the marker beacon receiving system at the intervals specified in the "Schedule or Inspection and Bench Checksrr contained in this manual. The inspection lvill be performed by a qualified certificated mechanic or a repair station, using ramp test equip­ ment which will perform the tests listed in paragraphs 1, 2 and 3. Following the test equipment manufacturer's instructions: 1. Position the ramp test equipment directly beneath the marker beacon antenna and set the test generator for 20,000 microvolts output with 90 percent modulation at 3000 cps. 2. Turn on the airplane marker receiver and set the 11 High-Low" switch for "High" (maximum) sensitivity and determine that a 3000 cps tone is clearly audible in the airplane speaker and headset. The inner marker (white) indicator light should be brightly lighted at this time. 3. Repeat the above procedure using the 1300 and 400 cps tones, and make the same determinations. The amber indicator light (middle marker) should be brightly lighted when 1300 cps is applied, and the blue indicator light (outer marker) should be lighted when 400 cps is applied. 4. Repeat steps 2 and 3 with the "High-Low" switch in the "Low" position and determine at least that each audio tone is audible. 5. Make a thorough visual inspection of the receiving installations for physical security, electrical cable connections, condition of antenna, etc. 6. Enter the date, name of the agency or person conducting the inspection, indicate satisfactory or unsatisfactory performance, in the maintenance record of the marker receiver. The above inspection will also be made after the repair or replacement of any component of the marker receiving systems. ### Page 41 Attachment 1 · · FLIGHT DIRECTOR INSPECTION GAINS MODEL 263-B AC 91-16 8/7/67 The following inspection will be performed on the flight director system at the intervals specified in the 11 Schedule of Inspection and Bench Checks" contained in this manual. The inspection will be performed by a qualified certificated mechanic or a repair station, using ramp test equip­ ment to radiate the necessary test signals. Although not required in the Category II maintenance program, the VOR functions of the flight director system will also be tested, following the sequence of tests below. Ramp test equipment capable of radiating standard VOR/ILS test signals, and marker beacon test signals will be used to perform the tests. 1. Preparation a. Determine that all power to the flight director system is OFF. b. Determine that the flight director control MODE SELECTOR switch is in the OFF position. c. Connect external power supply to aircraft and apply power. 2. Functional Test a. Turn on power to all units of the flight dir ec tor system. b. All ow five minutes for equipment \>larmup, and then check erecti on of the vertical gyro. When the gyro is erected, the horizon bar will be centered, provided the airplane is level, and the GYRO flag will be retracted. c. Determine that the gyro-stabilized magnetic compass is slaved by observing the azi muth card on the Course Ind ic at or for correct air­ plane magnetic headin g . Determine that the COHPASS, CO!-fPUTER and GYRO flag alarms, and V-bar command indicator are in the 0 out of sight" position. d. Turn on VOR/LOC and glide slope receivers and tune the VOR receiver to the VOR test signal frequency. e. Turn the flight director control NODE SELECTOR to SC (speed control) position and determine that the V-bar command indicator comes into view and that SC appears in the right annunciator window of the flight director indicator. f. Turn the MODE SELECTOR control to HDG position. The GYRO CONPUTER and COMPASS warning flags should remain "out of sight." The course indicator azimuth card should indicate the airplane magnetic head­ ing. The annunciator windows should be blank. ### Page 42 AC 91-16 8/7/67 g. h. i. j. k. 1. m. n. o. Attachment 1 Page 41 If the heading marker has been left set in another position, turn the HDG knob on the course indicator until the heading marker is under the lubber line . The V-bar should center (wings level). Rotate the PITCH COM}~D (on control unit) control knob clockwise, and determine that the V-bar command indicator in the flight indica­ tor moves upward. The V-bar should move downward for a counter­ clockwise rotation . Return PITCH COMMAND control knob to zero (V-bar aligned with airplane symbol). Vary the heading marker 10 degrees both sides of the lubber line. The V-bar should call for a bank toward the new headings . Return the heading marker to the lubber line, The V-bar should center (wings leve,l). Turn the }~TITUDE HOLD toggle switch (on control unit) ON. Rotate the PITCH COM}~D control throughout its range and determine that the V-bar does not move, and that ALT appears in the left annuncia­ tor window of the director indicator. Turn ALTITUDE HOLD to OFF. Rotate the COURSE knob on the course indicator until the course arrow is 15 degrees to either side of the course to the test signal, and set the MODE SELECTOR to VOR/LOC. Determine that HDG/VL appears in the right annunciator window of the director indicator, and the V-bar follows the heading marker for bank commands. The VOR/LOC flag alarm shoul d be "out of sight." Rotate the COURSE knob until the course arrow is on the inbound course to the test signal. The lateral deviation bar should center and the TO-FRON arr ow should point to the head of the course arrow. When the system has captured the course, the right annunciator window should .be blank. Move the course arr ow ten degrees both sides of the inbound course to the test signal. The V-bar should call for banks toward the new courses, and center (wings level) when the new courses are reached. Tune the pilot's navigation receivers (one at a time) to the test set localizer signal frequency and set the MODE SELECTOR to GS MAN. GS should appear in the left annunciator window. Set course arrow to the inbound localizer course. The lateral deviation bar should show the localizer path in relati on to the miniature airplane symbol. The ALTITUDE HOLD switch should return to OFF. The glide slope scale and pointer should become visible, and the localizer deviation display should beco me visible and operate. Pre ss the SC switch on the pil ot's wheel. Deter mine that the MODE SELECTOR returns t o SC mode and that SC appears in the right annun­ ciat or window. Det ermine that the V-bar calls for sufficient pitch­ up indication to effect a safe go-around. ### Page 43 lo.ttachment t­ AC 91-16 8/7/67 p. After approximately three seconds, set the MODE SELECTOR to GS Y~N. The V-bar should be centered until the system again captures the localizer and glide slope course. q. Turn the HODE SELECTOR to GS AUTO and determine that GS remains displayed in the left annunciator but that the right annunciator remains blank. Turn the marker test set on and set it to radiate a standard marker test signal with 1300 cps modulation. \\lhen the amber (middle) marker lamp (in the cockpit) is lighted, EXT should appear in the right annunciator lvindow. r. Press the SC switch on the pilot's control wheel. The t-!ODE SELECTOR should revert to SC mode and SC should appear in the right annunci­ ator window. The V-bar should call for fly-up. During the above tests determine that the second in command's course inqicator and flight director indicator display the same annunciator signals, alarm action, position and command signals as the pilot's display. s. Upon completion of the tests, turn NODE SELECTOR to OFF, radio and power switches OFF, and disconnect external powe~ sup?lY to the airplane. t. Hake a thorough visual inspection of the flight director system for physical security of mounting in racks and instrument panel, electrical cable connection security, condition of dust covers and cases, inoperative instrument lights, etc. u. Enter the date, name of the agency or person conducting the check, indicate satisfactory or unsatisfactory performance in the mainten­ ance record of the flight director system. The above check will also be made after the repair or replacement of any component of the flight director system. ### Page 44 AC 91-16 8/7/67 Sectip.n VII PILOT-CONDUCTED FUNCTIONPL FLIGHT CHECKS Attachmel!::: 1 Page 43 (and 44) ### Page 45 AC 91-16 8/7/67 Section VII Attachment 1 Page 45 PILOT-CONDUCTED FLIGHT CHECK FOR LOCALIZER, GLIDE SLOPE, AND MARKER RECEIVERS: AND, BAROMETRIC AND RADIO ALTIMETER PERFORMANCE TESTS This functional flight check will be made to check the operation of the localizer, glide slope, and marker receiving systems; and, the barometric and radio altimeter systems. It must be performed by a pilot holding Category II pilot authorization for the type airplane in which the instruments and equip­ ment are installed. To minimize potential traffic conflict, pilots should contact the controlling air traffic control (ATC} facility, describe the planned maneuver, and obtain clearance to conduct the flight check . To elim­ inate radio frequency congestion,whenever possible such coordination should be effected in person or by telephone prior to the flight. 1. The flight check will be conducted in two stages designated as Stage 1 and Stage 2. Stage 1 will consist of a check of the proper sensing and indication of the radio and electronic instrumentation systems. Stage 2 will consist of a check during a simulated Category II ILS approach and landing (or go-around). Either Category I or Category II ground facilities may be used, providing that there are no outstanding NOTAMs restricting the use of the facility. The sequence of checks is optional. However, the sequence outlined below is intended to accomplish all required tests with minimum flight time. For convenience, see plan view, sketch attached. 2. Stage 1 - Flag alarm and deviation sensitivity check; first, of the localizer receiving systems on all beadings; and, then of the glide slope receiving systems by intercepting the localizer inbound heading at an angle. a. With the airplane at least 15 miles from the ground facility, and at an altitude of 2000 feet above the terrain and positioned so that the localizer deviation indicator reads full scale deflection from the front course line of the localizer ground station, fly the airplane in the appropriate right-hand or left-band 360 degree circle to cross the localizer center line , holding a ten degree bank in the turn. Under all of these conditions, the flag alarm indicator should be out of sight at all times. The localizer deviation indicator should move from full scale deflection to on-course to full scale op­ posite deflection. Be sure to observe that the indicator moves in the proper direction. b. Determine the altitude at which the glide slope intercepts the outer marker. While flying at that altitude, establish an inbound course to pass through the localizer c.ourse in the vicinity of the outer marker at approximately a 45 degree angle to the localizer centerline. The fly-through of the localizer course should begin at a point far enough beyond the outer marker to give full scale fly-up deflection of the glide slope indicator. Determine that: ### Page 46 Attachment 1 ( 1) (2) AC 91-16 8/7/67 Normal glide slope indicator action is from full fly-up to full fly-down while passing through the glide slope path. The glide slope alarm indicator is out of sight at all times. 3. Stage 2 - Use a current ILS approach chart for the facility on which the check is to be conducted. Set the airplane altimeter barometric scale to the current altimeter setting for that facility. Conduct a simulated Category II ILS approach and observe the following: a. All warning systems indicate normal operating conditions. b. Upon intercepting the glide slope at the outer marker, note that the barometric altimeters indicate proper altitude. c. Test the radio altimeter for proper operation and required indications using the self-test feature of the equipment. The self-test feature of this equipment is shop adjusted to indicate a simulated 100 foot altitude when the self-test function is activated . d. Observe proper altitude indication at the middle marker. e. Observe proper altitude indication at the decision altitude. f. No unusual roughness or excessive attitude changes occur after leaving the outer marker . g. Observe that the correct marker receiver indications are received while passing over the outer marker, middle marker, and inner marker (if installed at the facility). Observe that the marker indicator light colors are received in the following sequence: Marker Beacon Outer Middle Inner Light Color Blue Amber White 4. Upon completion of the flight check, make an entry in the inspection record for the localizer receivers, glide slope receivers, marker receiver, radio altimeter, and barometric altimeters showing the date, name of pilot, whether performance was satisfactory or unsatisfactory, and indicate that it was a pilot-conducted flight check. ### Page 47 LOCALIZER ~Ol&H ~ 360 deg. LOCALIZER FRONT COURSE C/L 15 F·ULE A I~. FOR l.OCALIZ:iiR CIRCLIN G C!iECK. PIAN VIE','I OF LOCALIZER AND GLID.R SLOPB PERFOR~.NCB TESTSI STAGES la and lb. IM --~-- oo> -o ..... ....... \0 Q\ .... .._, I ~ Q\ ### Page 48 AC 91-16 8/7/67 Section VIII BENCH CHECK PROCEDURES Attachment 1 Page 49 (and 50) ### Page 49 AC 91-16 8/7/67 LOCALIZER RECEIVER BENCH CHECK AJAX NODEL 16-L Attachment 1 Page 51 The localizer receiver bench check will be performed by a radio repairman, or a qualified technician working under his supervision. The standards and procedures contained in RTCA Paper 23-63/D0-117, "Standard Adjustment Cri­ teria for Airborne Localizer and Glide Slope Receivers," dated March 4, 1963, will be used to perform the tests and adjustments specified in pars. 4 thru 7 below. 1. Remove the dust cover and thoroughly inspect the receiver for cleanli­ ness, chafed wires, leaking components, bulging resistors, impending parts failure, and need for lubrication, repair, or replacement of parts. 2. Perform any cleaning operations necessary, using an air jet of clean, dry,compressed air and a small, soft-bristled brush . Use solvent and a brush where necessary to remove dirt deposits. Do not use excessive air pressure or solvents that will damage any receiver components. 3. Check cable receptacles for dirty or broken connector sockets. Repair or replace as necessary. 4. Check the deviation indicator centering by applying a 1000 microvolt standard localizer centering signal and adjusting the centering/balance control of the receiver to produce an on-course indication or zero indi­ cator deflection. 5. Check the indicator deflection sensitivity by applying a 1000 microvolt standard localizer deviation signal and adjusting the course sensitivity control of the receiver to produce standard deflection (90 microamperes) plus/minus 5% on the deviation indicator. Any error should be balanced between the 90 cps and 150 cps sectors. 6. Check the flag alarm by alternately applying a standard localizer test signal of 3 mv (rated receiver sensitivity) and 20,000 mv, and adjust the receiver alarm circuitry to produce a flag alarm current of 375 plus/minus 5 microamperes. Determine that the alarm flag is in the "out of sight" position. The adjustments made to meet this requirement shall provide the following additional alarm performance automatically without further readjustments: The alarm flag shall be plainly visible: a. With the loss of either modulation signal from the rf test signal, b. With the complete loss of rf input signal, c. When both modulation signals are decreased by 50% of standard value. ### Page 50 Attachment 1 Page 52 AC 91-16 8/7/67 7. Check the audio output for m~n1mum level of 100 milliwatts into a 600 ohm load with 5 microvolts input modulated 30% with ·a 1000 cps audio signal. 8: Upon completion of the adjustments made in paragraphs 4 throu gh 7, above, check the receiver performance on at least three other channels. If further adjustment is necessary due to interaction of controls or other causes, repeat the adjustment procedures as necessary to obtain the required performance on all channels checked. 9. Re-install the dust cover and touch up any damage to the finish. 10. Enter the date, name _!ind certificate number of the repair facility that performed the bench check in the maintenance record of the localizer receiver. This completes the bench check. 11. Re-install the receiver in the airplane and perform the inspection of the localizer receiving system required in the schedule of inspections. Enter the date, name of the pers ·on performing the inspection, whether technician or pilot, indicate satisfactory or unsatisfactory performance, in the maintenance record of the localizer receiver. ### Page 51 AC 91-16 8/7/67 Attachment 1 Page 53 (and 54) WORK CHECK SHEET FOR LOCALIZER RECEIVER AJAX MODEL 16-L This sheet will be completed for each bench check of the localizer receiver and filed in the airplane maintenance records. Receiver serial number ------ 1. Visually inspect receiver and chassis. 2. Clean, lubricate, replace parts as necessary. 3 . Check cable receptacles. Glean or replace as required. 4. Adjust qeviation indicator centering/balance. 5. Adjust deflection sensitivity. 6. Adjust fla g alarm circuitry. 7. Check audio output for a minimum level of 100 mw. 8. Other channels checked __ -:me, ____ ra.c, ___ --:me. 9. Re-install dust c over, touch-up paint. 10 . Make e ntry in localiz e r recei v er maintenanc e record. 11. Re-install receiver in airplane and perform inspection. Date By ------------------ Repair Station Name & Cert. No. u Ll Ll Ll Ll Ll Ll Ll Ll I I I I I I ### Page 52 AC 91-16 8/7/67 GLIDE SLOPE RECEIVER BENCH CHECK AJAX MODEL 22-G Attachment 1 Page 55 The glide slope receiver check will be performed by a radio repairman or a qualified technician working under his supervisi on. The standards and procedures contained in l~TCA Paper 23-63 / D0-117, dated Harch 14, 1963, "Standard Adjustment Criteria for Airborne Localizer and Glide Slope Receivers," will be used to perform the tests and adjustments specified in paragraphs 3 through 6 below with the exception of item 4. It is necessary to increase receiver deflection sensitivity to meet Category II approach performance requirements. 1. Remove the dust cover and thoroughly inspect the receiver for cleanliness, chafed \>lires, leaking components, bulging resistors, impendin g parts failure, and need for lubrication, repair, or replacement of parts. 2. Perform any cleaning operations necessary, using an air jet o£ clean, dry, compressed air and a small, soft-bristled brush. Use solv ent and a brush where necessary to remove dirt deposits. Do not use excessive air pressure or solvents that will damage any receiver components. 3. Check the deviation indicator centering by applying a 700 microvolt stan­ dard glide slope centering signal and adjusting the centering/balance control of the receiver to produce an on-course indication or zero indica­ tor deflection. 4. Check the deviation indicator deflection sensitivity by applying a 500 microvolt standard glide slope deviation signal and adjusting the course sensitivity control of the receiver to produce standard deflection (78 microamperes) plus/minus 5% on the deviation indicator. 5. This receiver is equipped with course softening. Apply a standard glide slope deviation signal of 14,000 microvolts and adjust the course soften­ ing control on the receiver to produce standard deflection plus/minus 5% on the deviation indicator. 6. Check the flag alarm by alternately applying a standard glide slope test signal of 20 microvolts (rated receiver sensitivity) and 20,000 microvolts, and adjust the alarm circuitry to produce a flag alarm current of 375 plus/r: ,inus 5 microamperes. Determine tha: the flag alarm is in the " out of sight'' position. The adjustments made to meet this requirement shall provide the following additional flag alarm performance automatically without further readjustments: The flag alarm shall be plainly visible or in the alarm c ondition: a. With the loss of either modulation signal from the rf signal, ### Page 53 Attachment 1 b . With the complete loss of rf input signal, AC 91-16 8/7/67 c. When both modulation signals are decreased by 50% of standard value. 7. Upon completion of the adjustments required in paragraphs 3 through 6, check the receiver performance on at least three other channels. If further adjustment is necessary due to interaction of controls or other causes, repeat the adjustment procedures as necessary to obtain the stated performance requirements. 8. Re-install the dust cover and touch up any damage to the finish. 9. Enter the date, name and certificate number of the repair facility that performed the bench check in the maintenance record of the glide slope receiver . This completes the bench check. 10. Re-install the receiver in the airplane and perform the inspection of the glide slope receiving system required in the schedule of inspections. Enter the date, name of the person performing the inspection, whether technician or pilot, and indicate satisfactory or unsatisfactory performance in the maintenance record of the glide slope receiver. ### Page 54 AC 91-16 8/7/67 MARKER RECEIVER BENCH CHECK VOLE MODEL AV-21 Attachment 1 Page 57 The marker receiver bench check will be performed by a radio repairman, or a qualified technician working under his supervision. The inspection and bench check will be performed using the following proce­ dures and referring to the VOLE AV-21 maintenance manual No. 334-21 where necessary: 1 . Remove the dust cover and thoroughly inspect the rec.eiver for cleanli­ ness, chafed wires, leakin g components, bulgin g resistors, impending parts failure, and need for lubrication, repair , or replacement of parts. 2 . Perform any cleanin g operat ions necessary, usin g an air jet of clean, dry, compressed air and a small, soft-bristled brush . Use solvent and a brush where necessary to remove dirt deposits. Do not use excessive air pressure or solvents that will damage any receiver components. 3. Adjust the receiver sensitivity by setting the "High-Low" switch to "Low11 and applying a 2800 microvolt 75 me test signal modulated 90% at a fre­ quency of 1300 cps to the receiver. Measure the voltage across the amber indicators on the test panel . It should be 3.3 volts. If this value is not indicate d , c onsult the manufacturer's maintenance manual for adjustment procedures. 4. Check the indicator lamp selectivity by applying a 200 ,000 micro volt 75 me test signal modulated 90% at frequencies of 400 cps, 1300 cps, and 3000 cps, with the 11 High-Low " switch set to "Hi gh'' ·. Det ermine that the blue indicator light i lluminates when 400 cps is applied; the amber light when 1300 cps is applied; and, the white light when 3000 cps is applied. The lamp that illuminates should have at least 4 . 5 volts ap­ plied to it, and the other two no mor e than 1. 0 volt impressed across them as measured by an AC VTVM. 5. Perform checks to determine the followin g : a. Audio output is at least 100 milliwatts, at 400 , 1300, 3000 cps modulation within a signal input range of 20, 000 to 200 ,000 micro­ volts and the "Hi gh-L ow" switch set to "Low". b . Audio noise is more than 50 db below 100 milliwatts in the absence of an rf signal and a signal-plus-noise to noise ratio of at least 20 db over an input signal lev e l range of 200 to 20,000 microvolts with the "Hi gh-Low11 switch set to "Low". 6. Re-install the dust cover and t ouch up any damage to the finish. ### Page 55 Attachment 1 AC 91-16 8/7/67 7. Enter the date, name and certificate number of the repair facility that performed the bench check in the maintenance record of the marker receiver. This completes the bench check. 8. Re-install the receiver in the airplane and perform the inspection of the marker receiving system required in the schedule of inspections . Enter the date, name of the person performing the inspection, whether technician or pilot, and indicate satisfactory or unsatisfactory performance in the maintenance record of the marker receiver. ### Page 56 AC 91-16 8/7/67 Attachment 2 Page 1 **ENGINEERING EQUIPMENT INSTALLATION APPROVAL** CRITERIA AND ACCEPTABLE MEANS OF COMPLIANCE - CATEGORY II AIRBORNE NAVIGATION, INSTRlJNENT AND FLIGHT CONTROL SYSTEHS 1. EQUIPMENT APPROVAL CRITERIA - GENERAL. Subject to a satisfactory engineer­ ing approved inspection and test program, airborne navigation instrument and/or flight control equipment may be eligible for installation approval as part of an installed system when it is: a. Found to comply with the requirements of an applicable technical standard order or type certificate, or b. Found to comply with applicable Federal Aviation Regulations and approved as part of an airplane under a type certificate or supple­ mental type certificate, or c. Found to comply with other pertinent specifications adopted by the FAA Administrator; e.g., military standards or a foreign government 1 s validation which has been found to be compatible with the intent of the appropriate Federal Aviation Regulations. 2. INSPECTION AND TEST PROGPJU~. a. This engineering program involves first an agreement between the appli­ cant and the appropriate FAA Engineering and Manufacturing Regional or District Office which identifies the individual or combined systems proposed as a Category II installation. After a design and ground test evaluation, a type inspection authorization or similar document is usually issued which will specify those additional conformity, ground and flight inspections considered necessary. Also included in the pro­ gram will be a determination of satisfactory installation practices, freedom from interference, performance of intended functions and com­ patibility with ground navigation facilities and the Air Traffic Control System. b. System Performance Requirement. For the combination of systems to provide the level of accuracy, reliability and compatibility needed to assure an approach capability which is considered acceptable to the FAA Administrator, each indivioual system should be found to perform i.ts intended function in accordance with the following: (1) Data Display . All displays of information essential for the use of the flight crew in a Category II installation should in­ corp orate such positioning, marking and lighting as will permit accurate and timely utilization of such information and recogni­ tion of malfunctions by pilots of average skill and reaction time. Par. l ### Page 57 Attachment 2 (2) AC 91-16 8/7/67 Control Functions. All systems which furnish signals directly to the airplane flight control system or the propulsion thrust control system should be so designed that if malfunction occurs, such malfunction does not result in an unsafe condition. Means for quick disengaging or overriding of each automatic control function should be immediately available and easily accessible to the flight crew without requiring the crew to apply excessive control forces. c. Function and Reliability Testing. In addition to the engineering inspection and test program, a program of function and reliability testing may be required for the purpose of supplementing analytical and test data, such as fault analysis and reliability studies, with accelerated service experience . The extent of the additional tests depends upon the complexity, number, nature of (or novel) design features incorporated in system and the record of previous tests and experience. Additional tests should be predicated on : (1) The extent of flight and ground time utilized during the devel­ opmental and type certification program and difficulties asso­ ciated therewith . (2) The service history of the device/systems when this device has been utilized on airplanes previously approved. 3. ACCEPTABLE MEANS OF COMPLIANCE FOR CATEGORY II INSTALLATION OF AIRBORNE NAVIGATION. INSTRUMENT AND FLIGHT CONTROL SYSTEMS. The minimum perform• ance standards applicable to systems which are to be used as a part of a Category II system shall be applied to the following: a. Localizer. The localizer system installation should comply with the following: (1) The localizer equipment should meet or exceed m1n1mum perform­ ance standards set forth in Federal Aviation Agency Technical Standard Order C36b, dated June 15, 1962, "Minimum Perf ormance Standards for Airborne ILS Localizer Receiving Equipment," or applicable type certificate, or RTCA Paper 20-63/D0-115, dated February 14, 1963, "Minimum Performance Standards - Airborne ILS Localizer Receiving Equipment. •t (2) The localizer system installation should meet or exceed the m1n4- mum performance standards set forth in RTCA Paper 69-60/D0 - 102, dated April 12, 1960, "Minimum In-Flight Performance Standards - ILS Localizer Receiving Equipment." ### Page 58 AC 91-16 8/7/67 (3) Attachment 2 Page 3 Display to the pilot positive visual indication to show degrada­ tion of localizer system performance under the following conditions: (a) The absence of either or both modulation signals. (b) The reduction of either or both modulation signals to one­ half the normal 20%. (c) When a difference of depth of modulation equal to 0.093 : 0.002 produces an output of less than one-half normal response to this standard localizer deviation signal. (4) The localizer receiving centering err.or should be within 5 ua on a 95% probability basis under the following conditions, using a standard test signal: (a) Variation of R.F. signal level from 50 to 1000 uv. NOTE: This represents the variation of R.F. signal level expected during the final phase of an ILS approach. (b) Variation of DC power over the range of 24 to 28 volts or AC power over the range of 105 to 120 volts. (c) Variation of ambient temperature over the limited range expected during a normal ILS approach. The nominal ambient temperature range is defined as +10°C. to +40°C. Operation over a different temperature range in a particular airplane will require special coordination. (5) The localizer receiving .equipment should be adjusted in accordance with RTCA Paper 23-63/D0-117, dated March 14, 1963, "Standard Ad­ justment Criteria for Airborne Localizer and Glide Slope Receivers." b. Glide Slope. The glide slope system installation should comply with the following: (1) The glide slope equipment should meet or exceed the m~nLmum per­ formance standards set forth in Federal Aviation Agency, Techni­ cal Standard Order C34b, dated May 9, 1963, "Minimum Performance Standards for Airborne ILS Glide Slope Receiving Equipment," or applicable type certification, or RTCA Paper 21-63/D0-116, dated February 14, 1963, "Minimum Performance Standards - Airborne ILS Glide Slope Receiving Equipment." (2) The glide slope system installation should meet or exceed the minimum performance standards setfbrth in RTCA Paper 233-59/ D0-101, dated December 8, 1959, "Minimum In-Flight Performance Standards ILS Glide Slope Receiving Equipment." ### Page 59 Attachment 2 (3) AC 91-16 8/7/67 Display of the pilot positive visual indication to show degrad­ ation of glide slope system performance under the following conditions: (a) The absence of either or both modulation signals. (b) The reduction of either or both modulation signals to one­ half of their normal 40%. (c) When a difference of depth of modulation equal to 0.091± .002 produces an output of less than one-half normal re­ sponse to this standard glide slope deviation signal. (4) Centering Error. The glide slope centering requirements outlined in RTCA Paper 222-58/D0-89 are applicable for Category II installation approval. (5) The glide slope receiving equipment should be adjusted in accord­ ance with RTCA Paper 23-63/Do-117, dated March 14, 1963, "Stand­ dard Adjustment Criteria for Airborne Localizer and Glide Slope Receivers." c. Automatic Pilot/Coupler. When an automatic pilot/coupler system is used as part of Category II installation, it should, in addition to complying with applicable TSO and FARs, provide the following per­ formance under the test conditions stated: (1) Airplane Speed - Maximum and minimum operational approach speeds . (2) Wind Conditions - Surface downwind component of 10 knots. Wind shear of 4 knots per 100 feet altitude applied along the runway or across the runway individually, commencing at an altitude of 500 feet. The effects may be shown analytically, or correlated with some Flight Test data. (3) Localizer Performance - (a) The airplane should be stabilized on the localizer for the purpose of demonstration before the outer marker is intercepted on a normal inbound approach. (b) From the outer marker to an altitude of 300 feet above run­ way elevation on the approach path, the automatic pilot/ coupler should cause the airplane to track automatically to within ± 35 microamperes (95% probability) of the indicated localizer course. The performance should be free to sus­ tained oscillations. ### Page 60 AC 91-16 8/7/67 (c) Attachment 2 Page 5 From an altitude 300 feet above runway elevation on the approach path to the decision altitude (100 feet), the auto­ matic pilot/coupler should cause the airplane to track automatically to within : 25 microamperes (95% probability) of the indicated course. The performance should be free of sustained oscillations. (4) Glide Slope Performance - {a) For the purposes of the demonstration, the airplane should be stabilized on the glide slope before an altitude of 700 feet above the field level is reached. (b) From 700 feet altitude to the decision altitude, the auto­ pilot/coupler without manual assistance should cause the airplane to track the center of the indicated glide slope to within : 35 microamperes or ± 12 feet, whichever is the larger, without sustained oscillations. When the pilot is in the loop providing manual assistance, ~ 75 microamperes tracking tolerance may be used. d. Flight Director Systems. When a flight director system is used as part of a Category II installation, it should provide for the follow­ ing performance under the test conditioxsstated: {1) Airplane Speed - Maximum and Minimum operational approach speeds. {2) Wind Conditions - Surface crosswind component of 15 knots. Sur­ face downwind component of 10 knots. Wind sheer of 4 knots per 100 feet altitude applied along the runway or across the runway individually, commencing at an altitude of 500 feet. The effects may be shown analytically if correlated with some flight test data. (3) Mode selection and Indication - (a) Manual Selection should be positive, and the selection should be clearly identified. (b) When the mode of operation is not shown by the manual mode selector and by the command display behavior, means should be employed to clearly annunciate the existing mode .. (4) Localizer Performance - (a) The airplane should be stabilized on the localizer for the purpose of demonstration before the outer marker is inter­ cepted on a normal inbound approach. ### Page 61 Attachment 2 (b) (c) AC 91-16 8/7/67 From the outer marker to an altitude of 300 feet above run­ way elevation on the approach path, the flight director should permit the pilot to track within ~ 35 microamperes (95% probability) of the indicated localizer course. The performance should be free of sustained oscillations. From an altitude 300 feet above runway e l evation on the approach path to the decision altitude (100 feet), the flight director should permit the pilot to track to within ± 25 microamperes (95% probability) of the indicated course. The performance should be free of sustained oscillations. (5) Glide Slope Performance - (a) For the purposes of the demonstration, the airplane should be stabilized on the glide slope before an altitude of 700 feet above the field level is reached . (b) From 700 feet altitude to the decision altitude (100 feet) the fli ght director should permit the pilot to track the center of the indicated glide slope to within ± 75 micro­ amperes or~ 22 feet, whichever is the larger, without sus­ tained oscillations. e. Aut omatic Throttle System. (1) An automatic throttle system, if used, should provide safe oper­ ation under conditions which can reasonably be expected in normal service, including wind sheer, gusts and sideslips. The system should: (a) Automatically adjust throttles to maintain airplane speed to within t 5 knots of stabilized programmed airspeed, but not less than computed threshold airspeed under all intended flight conditions . Prop er operating points such as refer­ ence speed or angl e of attack may be set manually or automatically. (b) Provid e throttl e application at a rate consistent with the recommendations of the appropriate engine and airframe manufacturers. (c) Maintain stable short period and phugoid airplane modes for all intended flight situations during manual and automatic fli ght control. (2) Malfunction of any part of the system should not restrict either pilot from maintainin g safe control of the airplane or engines. ### Page 62 AC 91-16 Attachment 2 8/7/67 Page 7 (a) Disconnect switch(es) ~eadily accessible to both pilot and second in command should be provided. (b) The throttle drive mechanism should be cesigned to permit manual overriding without application of excessive throttle forces. (c) The maximum servo velocity. attainable sn