Chapter 6. Subpart G--Operating Limitations and Information Section 1. General 1 § 23.1501 General.
a. Explanation.
(1) Flight Crew Information. This section establishes the obligation to inform the flight crew of the airplane's limitations and other information necessary for the safe operation of the airplane. The information is presented in the form of placards, markings, and an approved AFM. Appendix 4 can be used to assist in determining which methods of presentation are required.
(2) Minimum Limitations. Sections 23.1505 through 23.1527 prescribe the minimum limitations to be determined. Additional limitations may be required.
(3) Information Presentation. Sections 23.1541 through 23.1589 prescribe how the information should be made available to the flight crew.
b. Procedures. None.
2. § 23.1505 Airspeed Limitations.
a. Explanation. This section establishes the operational speed limitations for safe margins below design speeds. For reciprocating engine-powered airplanes, there is an option.
They may either establish a never-exceed speed (VNE) and a maximum structural cruising speed (VNO) or they may be tested in accordance with § 23.335(b)(4), in which case the airplane is operated under a maximum operating speed concept (VMO/MMO). For turbine-powered airplanes, a VMO/MMO should be established. Tests associat ed with establishing these speeds are discussed under § 23.253, High speed characteristics.
b. Procedures. None.
3. § 23.1507 Maneuvering Speed. This regulation is self-explanatory.
4. § 23.1511 Flap Extended Speed. This regulation is self-explanatory.
5. § 23.1513 Minimum Control Speed. This regulation is self-explanatory.
6. § 23.1519 Weight and Center of Gravity. This regulation is self-explanatory.
7. § 23.1521 Powerplant Limitations. Reserved.
8. § 23.1523 Minimum Flight Crew. Reserved.
9. § 23.1523 Minimum Flight Crew.
a. Information. The following should be considered in determining minimum flight crew:
(1) Basic Workload Functions. The following basic workload functions should be considered:
(i) Flight path control;
(ii) Collision avoidance;
(iii) Navigation;
(iv) Communications;
(v) Operation and monitoring of aircraft controls;
(vi) Command decisions; and
(vii) Accessibility and ease of operation of necessary controls.
(2) Workload Factors. The following workload factors are considered significant when analyzing and demonstrating workload for minimum flight crew determination:
(i) The impact of basic airplane flight characteristics on stability and ease of flight path control. Some factors such as trimmability, coupling, response to turbulence, damping characteristics, control breakout forces and control force gradients should be considered in assessing suitability of flight path control. The essential elements are the physical effort, mental effort and time required to track and analyze flight path control features, and the interaction with other workload functions.
(ii) The accessibility, ease, and simplicity of operation of all necessary flight, power, and equipment controls, including emergency fuel shutoff valves, electrical controls, electronic controls, pressurization system controls, and engine controls.
(iii) The accessibility and conspicuity of all necessary instruments and failure warning devices such as fire warning, electrical system malfunction, and other failure or caution indicators. The extent to which such instruments or devices direct the proper corrective action is also considered.
(iv) The complexity and difficulty of operation of the fuel system, with particular consideration given to the required fuel management schedule necessitated by c.g., structural, or other airworthiness considerations. Additionally, the ability of each engine to operate 156
continuously from a single tank or source that is automatically replenished from other tanks if the total fuel supply is stored in more than one tank.
(v) The degree and duration of concentrated mental and physical effort involved in normal operation and in diagnosing and coping with malfunctions and emergencies, including accomplishment of checklist, and location and accessibility of switches and valves.
(vi) The extent of required monitoring of the fuel, hydraulic, pressurization, electrical, electronic, de-icing, and other systems while en route. Also, recording of engine readings, and so forth.
(vii) The degree of automation provided in the event of a failure or malfunction in any of the aircraft systems. Such automation should ensure continuous operation of the system by providing automatic crossover or isolation of difficulties and minimize the need for flight crew action.
(viii) The communications and navigation workload.
(ix) The possibility of increased workload associated with any emergency that may lead to other emergencies.
(x) Passenger problems.
(3) Kinds of Operation Authorized. During minimum crew determination, consideration should be given to the kinds of operation authorized under § 23.1525. Inoperative equipment could result in added workload that would affect minimum crew. It may be determined that, due to minimum crew workload considerations, certain equipment must be operative for a specific kind of operation.
b. Acceptable Techniques.
(1) General.
(i) A systematic evaluation and test plan should be developed for any new or modified airplane. The methods for showing compliance should emphasize the use of acceptable analytical and flight test techniques. The crew complement should be studied through a logical process of estimating, measuring, and then demonstrating the workload imposed by a particular flight deck design.
(ii) The analytical measurements should be conducted by the manufacturer early in the airplane design process. The analytical process that a given manufacturer uses for determining crew workload may vary depending on flight deck configuration, availability of a suitable reference, original design or modification, and so forth.
(2) Analytical Approach.
(i) A basis for deciding that a new design is acceptable is a comparison of a new design with a previous design proven in operational service. By making specific evaluations and comparing new designs to a known baseline, it is possible to proceed with confidence that the changes incorporated in the new designs accomplish the intended result. When the new flight deck is considered, certain components may be proposed as replacements for conventional items, and some degree of rearrangement may be contemplated. New avionics systems may need to be fitted into existing panels, and newly automated systems may replace current indicators and controls. As a result of these evolutionary charac teristics of the flight deck design process, there is frequently a reference flight deck design, which is usually a conventional airplane that has been through the test of operational usage. If the new design represents an evolution, improvement attempt, or other deviation from this reference flight deck, the potential exists to make direct comparisons. While the available workload measurement techniques do not provide the capacity to place precise numbers on all the relevant design features in reference to error or accident potential, these techniques do provide a means for comparing the new proposal to a known quantity. Service experience should be res earched to assure that any existing problems are understood and not perpetuated.
(ii) After studying a new component or arrangement and exercising it in practical flight scenarios, a test pilot may not be able to grade that design in finer workload units than "better" or "worse than." If the pilot can say with reliability and confidence that it is or is not easier to see a display or to use an augmented control system than to use a functionally similar unit of a reference design, then these "better" or "worse than" judgments provide substantial evidence that workload is or is not reduced by the innovation. These “better” or “worse than” judgments should be corroborated b a reasonable sample of qualified pilots over various assumed flight regimes.
(A) If an early subjective analysis by FAA flight test personnel shows that workload levels may be substantially increased, a more in-depth evaluation of flight testing may be required to prove acceptability of the increased workload. In this case, there should be available workload latitude in the basic flight deck design to accommodate the increase.
(B) If the new design represents a "revolutionary" change in level of automation or pilot duties, analytic comparison to a reference design may have lessened value.
Without a firm database on the time required to accomplish both normally required and contingency duties, more complete and realistic simulation and flight testing will be required.
(3) Testing.
(i) In the case of the minimum crew determination, the final decision is reserved until a panel of experienced pilots has flown the airplane, trained and qualified in the airplane.
The training should be essentially that required for a type rating. When the applicant seeks single pilot approval, the evaluation pilots should be experienced and proficient in single pilot operations. Section 23.1523 contai ns the criteria for determining the minimum flight crew.
These criteria contain basic workload functions and workload factors.
(ii) The workload factors are those factors that should be considered when evaluating the basic workload functions. It is important to keep in mind the key terms basic workload and minimum cues when analyzing and demonstrating workload. For example, an evaluation of communications workload should include the basic workload required to properly operate the airplane in the environment for which approval is sought. The goal of evaluating crew complement during realistic operating conditions is important to keep in mind if a consistent evaluation of minimum flight crew is to be accomplished.
(iii) The flight test program for showing compliance should be proposed by the applicant and should be structured to address the following factors:
(A) Route. The routes should be constructed to simulate a typical area that is likely to provide some adverse weather and Instrument Meteorological Conditions (IMC), as well as a representative mix of navigation aids and ATC services.
(B) Weather. The airplane should be test fl own in a geographical area that is likely to provide some adverse weather, such as turbulence and IMC conditions, during both day and night operations.
(C) Crew Work Schedule. The crew should be assigned to a daily working schedule representative of the type of operations intended, including attention to passenger cabin potential problems. The program should include the duration of the working day and the maximum expected number of departures and arrivals. Specific tests for crew fatigue are not required.
(D) Minimum Equipment Test. Preplanned dispatch-inoperative items that could result in added workload should be incorporated in the flight test program. Critical items and reasonable combinations of inoperative items should be considered in dispatching the airplane.
(E) Traffic Density. The airplane should be ope rated on routes that would adequately sample high density areas, but should also include precision and nonprecision approaches, holdings, missed approaches, and diversion to alternate airports.
(F) System Failures. Consequences of changes from normal to failed modes of operation should be included in the program. Both primary and secondary systems should be considered.
(G) Emergency Procedures. A sampling of various emergencies should be established in the test program to show their effect on the crew workload.
Note: Before selecting the system failu re and emergency procedures that will be evaluated in the flight test program, analytical studies of proposed abnormal and emergency procedures should be conducted. The acceptability of all procedures should be verified and the crew workload distribution during 159
the execution of these procedures understood to assure selection of appropriate failure cases.
(4) Determining Compliance.
(i) The type certification team that serves as pilots and observers should be equipped with flight cards or other means that allow for record keeping of comments addressing the basic workload functions. These records should be accumulated for each flight or series of flights in a given day. In addition, the certification team should record the accuracy of using operational checklists. For the pur poses of this data gathering, the airplane should be configured to allow the team evaluators to observe all crew activities and hear all communications both externally and internally.
(ii) Each subparagraph of paragraph 23.1523 summarizes an observation of pilot performance that is to be made. Judgment by the certification team members should be that each of these tasks has been accomplished within reasonable pre-established workload standards during the test flights. A holistic pilot evaluation rationale is needed in view of the wide variety of possible designs and crew configurations that makes it unfeasible to assume that ratings are made against every alternative and against some optimum choices. The regulatory criteria for determining minimum flight crew do not adapt well to finely-scaled measurements. Specific feature and activity pass-fail judgments should be made. Pass means that the airplane meets the minimum requirements.
10. § 23.1524 Maximum Passenger Seating Configuration. This regulation is selfexplanatory.
11. § 23.1525 Kinds of Operation.
a. Explanation.
(1) Required Equipment. Refer to guidance under § 23.1583(h), paragraph 23.1583 of this AC, concerning required equipment for each certificated kind of operation.
(2) Icing. With respect to operations in ic ing conditions, it is important that operating limitations be established in order to specify the required equipment in § 23.1583(h) and to provide the proper placard required by § 23.1559 (flight in icing approved or prohibited).
12. § 23.1527 Maximum Operating Altitude.
a. Explanation.
(1) Safe Operation. Section 23.1527 requires the establishment of a maximum operating altitude for all turbine, turbo-supercharged, and pressurized airplanes based on operation limited by flight, structural, powerplant, functional or equipment characteristics.
Section 23.1501(a) requires limitations necessary for safe operation be established. Thus, if an unsafe condition occurs beyond a particular operating altitude for any airplane, that altitude should be established as a limitation under § 23.1501(a).
(2) Windshields and Windows. As stated in § 23.1527(a), pressurized airplanes are limited to 25,000 feet unless the windshield/window provisions of § 23.775 are met.
(3) Factors. The maximum operating altitude listed in the AFM should be predicated on one of the following:
(i) The maximum altitude evaluated;
(ii) The restrictions, as a result of either unsatisfactory structures, propulsion, systems, or flight characteristics, or all of these; or
(iii) Consideration of § 23.775 for pressurized airplanes.
b. Procedures. Assuming that the structure has been properly substantiated, the flight evaluation should consist of at least the following:
(1) Stall characteristics. Stall characteristics per §§ 23.201 and 23.203 with wing flaps up, gear retracted, and power at the maximum power that can be attained at the maximum altitude, not to exceed 75 percent maximum continuous.
(2) Stall warning. Stall warning, cruise c onfiguration only (§ 23.207).
(3) Longitudinal stability. Longitudinal stability, cruise configuration only (§§ 23.173 and 23.175).
(4) Lateral and directional stability. Lateral and directional stability, cruise configuration only (§§ 23.177 and 23.181).
(5) Upsets. Upsets, if required (§ 23.253).
(6) Systems operation. Systems operation, including icing system, if installed.
(7) Propulsion operation. Propulsion operation, including stall, surge, and flameout tests throughout the speed range from near stall to maximum level flight speed.
Section 2. Markings and Placards
1. § 23.1541 General.
a. Required Markings and Placards. The rule specifies which markings and placards must be displayed. Note that § 23.1541(a)(2) requires any additional information, placards, or markings required for safe operation. Some placard requirements are obscurely placed in other requirements. For example, § 23.1583(e)(4) requires a placard for acrobatic category airplanes concerning spin recovery. A checklist is provided in appendix 4 that may assist in determination of placards and markings required.
b. Multiple Categories. For airplanes certified in more than one category, § 23.1541(c)(2) requires all of the placard and marking information to be furnished in the AFM.
This practice is encouraged for all airplanes.
c. Powerplant Instruments. AC 20-88A provides additional guidance on the marking of powerplant instruments.
2. § 23.1543 Instrument Markings: General. AC 20-88A provides guidance on the marking of powerplant instruments.
3. § 23.1545 Airspeed Indicator. This regulation is self-explanatory.
4. § 23.1547 Magnetic Direction Indicator. This regulation is self-explanatory.
5. § 23.1549 Powerplant Instruments. This subject is covered in AC 20-88A.
6. § 23.1551 Oil Quantity Indicator. Reserved.
7. § 23.1553 Fuel Quantity Indicator. Reserved.
8. § 23.1555 Control Markings.
a. Examples of Emergency Controls.
(1) Reciprocating engine mixture controls and turbine engine condition levers.
Reciprocating engine mixture controls and turbine engine condition levers incorporating fuel stopcocks or fuel stopcocks themselves are considered to be emergency controls, since they provide an immediate means to stop engine combustion.
(2) Quick-disconnect/interrupt switch. Quick-disconnect/inte rrupt switch of an electric trim system.
b. Requirements. Section 23.1555(e)(2) covers the requirements for emergency controls.
9. § 23.1557 Miscellaneous Markings and Placards. Reserved.
10. § 23.1559 Operating Limitations Placard. Reserved.
11. § 23.1561 Safety Equipment.
a. Examples of Safety Equipment. Safety equipment includes such items as life rafts, flares, fire extinguishers, and emergency signaling devices.
b. Requirements. Sections 23.1411 through 23.1419 cove r the requirements for safety equipment.
12. § 23.1563 Airspeed Placards. This regulation is self-explanatory.
13. § 23.1567 Flight Maneuver Placard. This regulation is self-explanatory.
Section 3. Airplane Flight Manual and Approved Manual Material
1. § 23.1581 General.
a. GAMA Specification No. 1. General Aviation Manufacturers Association (GAMA) Specification No. 1, Revision No. 1, dated September 1, 1984, provides broad guidance for contents of a Pilot's Operating Handbook (POH) that will fulfill the requirements of an AFM, for certain airplanes under 6,000 pounds, if the POH meets all of the requirements of §§ 23.1581 through 23.1589. There is no objec tion to the title, "Pilot's Operating Handbook," if the title page also includes a statement indicating that the document is the required AFM and is approved by the FAA.
b. Optional Presentations. Beginning with amendment 23-21, applicants are provided with an option for the presentation of the required procedures, performance, and loading information. The regulatory requirements of the two options are given in §§ 23.1581(b)(1) and
23.1581(b)(2). The options are as follows:
(1) Section 23.1581(b)(1). The AFM must have approved limitations, procedures, performance, and loading sections. These approved sections must be segregated, identified, and clearly distinguished from unapproved information furnished by the applicant if any unapproved information is furnished. Normally, FAA approval is indicated by the signature of the FAA Administrator, or appointed representative, on the cover page and a page effectivity table so that it is clear to the operational pilot exactly which pages are applicable and the date of approval.
(2) Section 23.1581(b)(2). The AFM must have an approved limitations section and this approved section must contain only limitations (no procedures, performance, or loading information allowed). The limitations section must be identified and clearly distinguished from other parts of the AFM. The remainder of the manual may contain a mixture of approved and unapproved information, without segregation or identification. However, the other required material (procedures, performance, and loading information) must be determined in accordance with the applicable requirements of part 23. The meaning of "acceptable," as used in § 23.1581(b)(2)(ii), is given in the preamble to amendment 23-21. The applicable portion of the amendment 23-21 preamble is as follows:
"In finding that a manual is acceptable, the FAA would review the manual to determine that the required information is complete and accurate. The manual would also be reviewed to ensure that any additional information provided by the applicant is not in conflict with required information or contrary to the applicable airworthiness requirements."
(A) The indication of approval for the approved section should be as discussed in the preceding paragraph, paragraph (1). GAM A Specification No. 1 has been found to comply with the provisions of § 23.1581(b)(2).
c. Part 36 Noise Limitations or Procedures.
(1) Section 23.1581(b)(1). If the applicant chooses the § 23.1581(b)(1) option, operating limitations required by part 36 should be placed in the operating limitations portion of the AFM. Any part 36 procedures should be pl aced in the operating procedures portion of the AFM.
(2) Section 23.1581(b)(2). If the applicant chooses the § 23.1581(b)(2) option, the approved AFM should contain the following approved, but separate, portions:
(i) Operating limitations prescribed in § 23.1583. Note that § 23.1581(b)(2)(i) limits the information in this portion to that prescribed in § 23.1583. Since the present part 36 limitation is a weight limitation, the part 36 limitation may be included.
(ii) Operating procedures prescribed by part 36. Section 23.1581(a) requires part 36 procedures to be approved.
d. STC Procedures.
(1) AFM Options. STC applicants are responsible for preparing an AFM supplement when the airplane has been modified in such a manner that limitations, procedures, or performance has been changed. The supplement should be prepared in accordance with the guide provided in Appendix 5 and reflect the necessary supplemental information. Alternately, the applicant may choose to prepare a new AFM. If the applicant selects the latter option, the new AFM replaces the original AFM in its entirety.
(2) Performance. If the STC applicant does not want credit for any increased performance and demonstrates that the performance meets or exceeds all basic airplane performance, a general statement to that effect would be satisfactory. Some STC's that meet or exceed all performance requirements may also increase the fuel consumption reducing endurance. Applicants should a dd a note or change the performance information for endurance that clearly indicates this decrease to the pilot.
e. Additional Information. Some additional information items that are required for safe operation because of unusual design, operating, or handling characteristics are as follows:
(1) Strobe lights. Operation of strobe lights during flight through fog, clouds, or flying closely under an overcast;
(2) Carburetor heat. Use of carburetor heat;
(3) Flaps. Restricted use of flaps during sideslips;
(4) Propeller pitch. Management of propeller pitch when Beta Range is provided;
(5) Sand screens and engine heaters. Procedures for the temporary use of sand screens and engine heater devices;
(6) Feathering. Unusual feathering design where propeller will not feather with throttle closed;
(7) Fuel flow. Scheduling for fuel flow by e ngine mixture leaning procedure;
(8) Spin recovery. Unusual spin recovery techniques;
(9) Wheelbarrowing. Wheelbarrowing characteristics;
(10) Oscillations. Pilot-induced oscillations or os cillations caused by turbulence, particularly on swept-wing airplanes;
(11) Depressurization. Depressurization proced ures prior to landing;
(12) Automatic devices. Procedures for operation of automatic devices; that is, wing levelers, Mach trim, yaw damper, and so forth; and
(13) Flight guidance and control systems. Procedures for operation of integrated flight guidance and control systems. This should include proper pilot response to cockpit warnings, diagnosis of system failures, discussion of possible pilot-induced flight control system problems, and use of the system in a safe manner.
(14) Turbochargers. Procedures for normal operation, if appropriate, and abnormal and emergency operations.
2. § 23.1583 Operating Limitations.
a. Limitations Section. The purpose of the limitations section is to present the limitations applicable to the airplane model by serial number, if applicable, as established in the course of the type certification process in determining compliance with parts 23 and 36. The limitations should be presented without explanation other than those explanations prescribed in parts 23 and 36. The operating lim itations contained in the limitations section (including any noise limited weights) should be expressed in mandatory, not permissive, language. The terminology used in the AFM should be consistent with the relevant regulatory language.
b. GAMA Specification. GAMA Specification No. 1, Revision No. 1 dated September 1, 1984, section 2, provides guidance for the contents of the limitations section.
Additional guidance is provided below for "Kinds of Operation," "Fuel Limitations," and "Commuter Category."
c. Kinds of Operation Equipment List (KOEL). The KOEL is to be placed in the limitations section of the AFM since the KOEL items form part of the limitations applicable to airplane operation. The sample KOEL given in Appendix 6 lists systems and equipment for a specific airplane in an acceptable format. Although the sample KOEL may contain items that are not applicable to all airplanes, it may be used as a guide.
(1) Standardization. Although there is no specific fo rmat required for the KOEL, we recommend, in the interest of standardization, that the KOEL be placed in columns and each item of equipment required for a specific type of operation for which the airplane is approved be noted in the appropriate column. Regardless of the format used, the KOEL should provide for:
(i) The kinds of operation for which the airplane was type certificated (that is, day or night VFR, day or night IFR, and icing conditions).
(ii) The identity of the systems and equipment upon which type certification for each kind of operation was predicated and must be installed and operable for the particular kind of operation indicated. Systems and equipment necessary for certifi cation includes those:
(A) required under the basic airworthiness requirements;
(B) required by the operating rules;
(C) required by special conditions;
(D) required to substantiate equivalent safety findings;
(E) required by airworthiness directives (AD); and (F) either items of equipment or systems not specifically required under items
(i) through (v) of this paragraph, but used by the applicant in order to show compliance with the regulations.
(2) The KOEL should not:
(i) Contain those obvious components required for the airplane to be airworthy, such as wings, empennage, engines, landing gear, brakes, and so forth.
(ii) Contain an exceptions column.
d. Fuel Limitations. The fuel limitations information in GAMA Specification 1 may not be applicable, depending on the airplane certification basis.
e. Turbine Airplanes and Commuter Category Airplanes. For those performance weight limits that may vary with runway length, altitude, temperature, and other variables, the 166