# AC 121-22A: Maintenance Review Board Procedures - Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it) - Status: Historical - Version in force: [AC 121-22D](https://openairdocs.org/ac/121-22), approved May 31, 2024. This is a historical version - Approved: March 7, 1997 - Last reviewed: August 28, 2024 - Family: AC 121-22 - Cancels: [AC 121-22](https://openairdocs.org/ac/121-22) - Cancelled by: [AC 121-22B](https://openairdocs.org/ac/121-22B) - 14 CFR parts: 21, 25, 27, 29, 33, 35, 121, 135 - 14 CFR sections: [21.50](https://www.ecfr.gov/current/title-14/section-21.50), [23.1529](https://www.ecfr.gov/current/title-14/section-23.1529), [25.571](https://www.ecfr.gov/current/title-14/section-25.571), [25.1309](https://www.ecfr.gov/current/title-14/section-25.1309), [25.1529](https://www.ecfr.gov/current/title-14/section-25.1529), [27.1529](https://www.ecfr.gov/current/title-14/section-27.1529), [29.1529](https://www.ecfr.gov/current/title-14/section-29.1529), [33.4](https://www.ecfr.gov/current/title-14/section-33.4), [35.4](https://www.ecfr.gov/current/title-14/section-35.4) - Pages: 26 - PDF: https://openairdocs.org/files/sha256/71/21/71211acf676638cb2cc284f190d4f3785ac1844c730d5305a13997bb5268aa32 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/498AA3176CD47F93862569BC0057D2C8.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ac/121-22A ## Versions - [AC 121-22D](https://openairdocs.org/ac/121-22) (Current), approved May 31, 2024, 10 pages - [AC 121-22C](https://openairdocs.org/ac/121-22C) (Historical), approved Aug 27, 2012, 81 pages - [AC 121-22B](https://openairdocs.org/ac/121-22B) (Historical), approved Oct 29, 2010, 83 pages - [AC 121-22A](https://openairdocs.org/ac/121-22A) (Historical), approved Mar 7, 1997, 26 pages ## Text Each page's text from the PDF; open the PDF at a page with #page=N. Some pages are OCR from the scanned FAA advisory circular. OCR can misread letters and numbers. Those pages are marked (OCR). ### Page 1 U.S. Department of Transportation Federal Aviation Administration Advisory Circular AC NO: 121-22A DATE: 3l7l97 **MAINTENANCE REVIEW BOARD** PROCEDURES Initiated by: AFS-330 ### Page 2 U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: MAINTENANCE REVIEW BOARD Date: 3/7/97 PROCEDURES Initiated by: AFS-330 AC No: 12%22A Change: 1. PURPOSE. This advisory circular (AC) provides guidelines that may be used by industry during its development and revision of the initial minimum scheduled maintenance/inspection requirements for derivative or newly type-certificated transport category aircraft and powerplants for submittal to the Federal Aviation Administration (FAA) for approval. These initial minimum scheduled maintenance/inspection requirements are referred to in this AC as the Maintenance Review Board Report (MRBR). The requirements, after approval by the FAA, become a base or framework around which each air carrier develops its own individual maintenance program. NOTE: Mandatory terms used in this AC, such as “must,” and “shall,” are used only in the sense of ensuring the applicability of these particular methods of compliance when the acceptable means of compliance described herein is used. This AC does not change regulatory requirements and does not authorize changes in, or deviations from, regulatory requirements. 2. CANCELLATION. AC 121-22, Maintenance Review Board, dated January 12, 1977, is cancelled. 3. RELATED REGULATIONS. Title 14 of the Code of Federal Regulations (14 CFR) parts 21, 23, .25, 27, 29, 33, 35, 121, 135; ss 21.50, 23.1529, 25.571, 25.1309, 25.1529, 27.1529, 29.1529, 33.4, 35.4, 121.25,121.45, and 135.11. 4. RELATED READING MATERIAL. Airline/Manufacturer Maintenance Program Development Document, MSG-3, Revision 2, may be obtained from the Air Transport Association of America (ATA), at l-800-497-3326, ext. 950 (U.S. and Canada), 410-490-7951, ext. 950 (overseas), or FAX: 410-206-9789. c-4%74* Thomas C. Accardi Director, Flight Standards Service ### Page 3 **AC 121922A 317197 (THIS PAGE INTENTIONALLY LEFT BLANK)** ### Page 4 317197 AC 121922A CONTENTS Page No. **CHAPTER 1. GENERAL** 1. Background ............................................................................................................................. 2. Maintenance Review Board Report ....................................................................................... 3. Document Time Delivery Guidelines .................................................................................... 4. Instructions for Continued Airworthiness ............................................................................. 5 . - 10. Reserved ....................................................................................................................... **CHAPTER 2. INDUSTRY PARTICIPATION** 11. General .................................................................................................................................. 12. Industry Steering Committee ............................................................................................... 13. Working Groups ................................................................................................................... 14. Manufacturer ......................................................................................................................... 15 . - 25. Reserved ..................................................................................................................... **CHAPTER 3. FAA PARTICIPATION** 26. General .................................................................................................................................. 27. Maintenance Review Board ................................................................................................. 28. MRB Members ..................................................................................................................... 29. FAA WG Advisors ............................................................................................................... 30. Other Regulatory Authorities ............................................................................................... 31 . - 35. Reserved ..................................................................................................................... **CHAPTER 4. MRBR APPROVAL** 36. MRBR Approval Process ..................................................................................................... 37. Other Regulatory Authority Approval of the MRBR ......................................................... 38. Nonapproval Process of the Proposed MRBR or Revision ................................................ 39. MRBR or Revision Implementation .................................................................................... 40 . - 45. Reserved ..................................................................................................................... **CHAPTER 5. MRBR REVISIONS** 46. Annual Review ..................................................................................................................... 47 . - 55. Reserved ..................................................................................................................... **CHAPTER 6. RECOMMENDED MRBR FORMAT AND CONTENT** 56. Recommendations ................................................................................................................. 57 . - 65. Reserved ..................................................................................................................... APPENDIX 1. POLICY AND PROCEDURES HANDBOOK (PPH) (2 pages) .............................. APPENDIX 2. SUGGESTED ACRONYM LISTING FOR THE MRBR (2 pages) ....................... APPENDIX 3. SCHEDULED MAINTENANCE TASK DEVELOPMENT’(1 page) ..................... APPENDIX 3a. SCHEDULED MAINTENANCE TASK DEVELOPMENT and INSTRUCTIONS for CONTINUED AIRWORTHINESS PROCESS (1 page) ......................... 7 7 7 7 7 9 9 11 14 1 1 1 2 i ### Page 5 AC 121-22A 317197 (THIS PAGE INTENTIONALLY LEFT BLANK) ii ### Page 6 **317197 AC 121122A CHAPTER 1. GENERAL** 1. BACKGROUND. The development of maintenance programs has a long history dating back to Aeronautical Bulletin 7E of May 15, 1930. The process of developing maintenance programs for new aircraft and powerplants has evolved from one in which each air carrier proposed its own unique program to one in which the FAA and industry work together to develop the initial minimum scheduled maintenance/inspection requirements for new aircraft and/or powerplants. Early experience in the development of initial scheduled maintenance/inspection requirements revealed that a program of effective maintenance tasks could be developed through the use of logical analysis and decision processes. In 1968, a maintenance requirements decision and analysis logic was developed by an industry team called the Maintenance Steering Group-1st Task Force (MSG-1). a. MSG-1. MSG.1 procedures were used by the FAA and industry to develop the initial minimum scheduled maintenance/inspection recommendations for the B-747 aircraft and its powerplants. A later task force utilized the experience gained on the B-747 project to update the MSG.1 procedures so that a universal document could be applicable for future newly type-certificated aircraft and/or powerplants. This document was called the Maintenance Steering Group-2nd Task Force (MSG-2) document. b. MSG-2. MSG-2 procedures were used to develop the initial minimum scheduled maintenance/ inspection recommendations for aircraft/powerplants of the 1970’s. In 1980, the combined efforts of the FAA, the Air Transport Association of America (ATA), U.S. and European aircraft and engine manufacturers, and U.S. and foreign airlines generated new decision logic and analysis procedures contained in a new document called Maintenance Steering Group-3rd Task Force (MSG-3). c. MSG-3. In 1987, after using MSG-3 analysis procedures on a number of new aircraft and powerplants in the first half of the 1980’s, the airline industry decided that the benefits of the experience gained during those years should be used to improve the document for future applications. Thus, Revision 1 to MSG.3 was developed. d. MSG-3Rl. The FAA and industry have been using MSG-3Rl since 1988 for the development of current and future aircraft and powerplant MRBR’s. e. MSG-3R2. The FAA and industry have been using MSG-3R2 since 1993 for current and future aircraft and powerplant MRBR’s. **2. MAINTENANCE REVIEW BOARD REPORT.** a. An MRBR is prepared for aircraft intended for air carrier use according to the following guidelines. An MRBR is normally not prepared for transport category aircraft having a maximum certificated takeoff weight of 12,500 pounds or less. For transport category aircraft having a maximum certificated takeoff weight of more than 12,500 pounds but not more than 33,000 pounds, a Maintenance Review Board (MRB) is sometimes convened and an MRBR generated. However, for transport category aircraft of more than 33,000 pounds maximum certificated takeoff weight, an MRB is normally convened and an MRBR generated as an expeditious means of complying in part with the maintenance instruction requirements of Appendix H to 14 CFR part 25. It is a means, in part, of developing Instructions for Continued Airworthiness, as required by § 25.1529. b. An MRBR contains the initial minimum scheduled maintenance/inspection requirements for a particular transport category aircraft and on-wing engine program, but does not establish off-wing engine maintenance programs required by the Regulations. It should be developed in accordance with these guidelines and is not to be confused with, or thought of, as a maintenance program. After approval by the FAA, the requirements become a base or framework around which each air carrier develops its own individual maintenance program. Although maintenance programs vary widely from one air carrier to another, the initial requirements for Par 1 Page 1 ### Page 7 AC 121922A 317197 a particular type of aircraft will be the same for all. An air carrier’s total maintenance program (methods used to implement these requirements) must be approved by the FAA through operations specifications. 3. DOCUMENT TIME DELIVERY GUIDELINES. The time allotments for delivery and return of the various documents mentioned in this AC are intended to be used as a general guide. These allotments have been included as an approximation of the time needed by the various groups to process the material. 4. INSTRUCTIONS FOR CONTINUED AIRWORTHINESS. A flow chart, outlining the relationships between the various documents, including the MRBR, involved in the creation of the Instructions for Continued Airworthiness, is contained in Appendix 3a. **5. - 10. RESERVED.** Page 2 Par 2 ### Page 8 3m97 AC 121922A CHAPTER 2. INDUSTRY PARTICIPATION 11. GENERAL. The most recent logic process should be used for the development of MRBR’s. Although MRBR’s were once developed by combining MSG.2 and MSG-3 analysis procedures, this method has proved to be impractical today. And since many problems have been identified from using this method, the FAA has responded with a policy stating that the latest MSG analysis procedures must be used for the development of MRBR’s for all new or derivative aircraft. This policy, however, will be implemented on a case-bycase basis. 12. INDUSTRY STEERING COMMITTEE (ISC). The ISC membership should comprise representatives from aircraft, engine, propeller, and appliance manufacturers and intended air carriers. The ISC’s role is to develop and establish policy with regard to procedural matters for the development of the proposed MRBR, to direct the activities of the working groups (WG), and to prepare the MRBR proposal. It is also the function and responsibility of the ISC, under the direction of the ISC Chairperson, to perform the following functions: a. Determine the number and type of WG’s that will be necessary, and then organize those groups. b. Provide the MRB Chairperson with a list of the various types of WG’s, the name and affiliation of each WG member, and any changes as they occur. c. Develop and approve the Policy and Procedures Handbook (PPH) and forward it to the manufacturer for review and for transmittal to the MRB Chairperson. Further comments developed through this review process will be directed to the manufacturer by the FAA. (Guidance to be used during development can be found in Appendix 1). d. Arrange for necessary technical and MSG.3 training of all ISC and WG members and FAA advisors. e. Invite the MRB Chairperson and selected MRB members to ISC meetings. f. Invite other regulatory authorities to ISC meetings, with coordination of the MRB Chairperson.* g. Attend MRB meetings. h. Review all WG analyses and presentations. i. Identify ISC changes to WG proposals in the ISC meeting minutes. j. Provide supporting technical data/analysis for the proposed MRBR. k. Document and present the proposed MRBR to the manufacturer. 1. Review and provide comments on proposed revisions to the MRBR. 13. WORKING GROUPS. WG’s are to comprise representatives of the manufacturer air carrier and should be chaired by an industry representative appointed by the ISC. The should assign FAA personnel to act as advisors to each WG. FAA WG advisors should FAA engineering/design certification branches as well as appropriate personnel from AFS( ities include the following functions: and the purchaser/ MRB Chairperson include staff from WG’ s responsibil- craft using the latest revision of the MSG.3 process. b. Establish sampling requirements when MSG.3 analysis determines that such sampling is applicable and effective in the identification of the cause of failure. These failures could have an adverse effect on the continued airworthiness or safety of the aircraft. Par 11 Page 3 ### Page 9 AC 121-222 317197 14. MANUFACTURER. The manufacturer should perform the following functions: a. Receive the draft PPH from the ISC, and after review, transmit it to the MRB Chairperson. b. Provide general familiarization training for the MRB, ISC, and WG’s. c. Provide the ISC with an initial list of Maintenance Significant Items (MSI) and Structural Significant Items (SSI), with sufficient data to support the reason each item was selected. d. Provide industry WG’s with sufficient technical data to support the analysis of MSI’s and SSI’s in a timely and adequate fashion. e. Provide the ISC and appropriate WG’s (in a timely manner) with information concerning certification issues and resolutions regarding proposed tasks originating from the certification process, such as airworthiness limitation items or certification maintenance requirements (CMR). f. Ensure that the manufacturer’s manual(s) contain(s) information covering the on-aircraft systems/ powerplant tasks listed in the FAA MRBR. g. Participate in ISC and WG activities. h. Submit the MRBR Proposal to the MRB Chairperson at least 90 days prior to scheduled approval. For engines where discretionary sampling/analytical inspections are conducted by a manufacturer/air carrier, on an opportunity basis, the following procedures apply: (1) The manufacturer/air carrier shall notify the regulatory authority, in a timely manner, of the time and place of the inspection, in order to permit regulatory authority participation. When regulatory authority attendance is not possible, the manufacturer/air carrier must provide a copy of the inspection report to the regulatory authority. (2) Subsequent to the first three inspections of the complete product or modules after introduction into service, further regulatory authority participation will be determined on a case-by-case basis on technical issues only. NOTE: The Flight Standards offke responsible for coordinating FAA attendance at powerplant/auxiliary power unit (APU) opportunity inspections will be the Manager, Aircraft Evaluation Group, BOS-AEG. **15. - 25. RESERVED.** Page 4 Par 14 ### Page 10 **317197 AC 121122A CHAPTER 3. FAA PARTICIPATION** 26. GENERAL. This AC is designed around the maintenance/inspection development concepts embodied in MSG-3, as revised. To accomplish the development of an MRBR proposal in an orderly manner, the FAA should establish an MRB and select WG advisors, as described in this chapter. When the aircraft manufacturer formally notifies the Aircraft Evaluation Group (AEG) manager of the controlling FAA directorate of its intention to develop an MRB proposal, the AEG manager will assign a qualified person as MRB Chairperson to manage the MRB for the FAA. MRB members are to be selected by the MRB Chairperson with Washington Headquarters, AFS-330 concurrence. MRB member(s) assigned to engine and propeller WG’s will be selected by the Manager, Aircraft Evaluation Group, BOS-AEG, in coordination with the MRB Chairperson. 27. MAINTENANCE REVIEW BOARD. The MRB supports the development of an industry proposal or report containing the initial minimum scheduled maintenance/inspection requirements for a derivative or newly type-certificated transport category aircraft and its powerplants. The MRB also acts on the MRBR proposal or revision IAW these procedures. The MRB should include qualified FAA Flight Standards inspector personnel and engineering representatives from the controlling FAA directorate, as members to the board. The MRB Chairperson shall assign MRB members to work as advisors to the industry WG’s. It is also the function and responsibility of the MRB, under the direction and management of the MRB Chairperson, to perform the following functions: a. Determine the number and type of FAA personnel that are necessary, and then organize them. b. Provide the ISC Chairperson with a list of FAA personnel names, their affiliations, assignments, and changes as they occur. c. Invite other authorities, in coordination with the AEG manager and the aircraft manufacturer, to participate in the MRB, and coordinate the activities of other regulatory authorities through their representatives. d. Obtain letters of confirmation between the FAA and each participating regulatory authority, and inform the ISC Chairperson of participating regulatory authorities. e. Establish and maintain a file of all MRB proceedings for the MRB historical file. f. Establish the extent of regulatory authority participation and assignment of WG advisors. g. Brief other regulatory authorities regarding MRB policy and procedures before and during the MRB process. h. Accept the PPH, following a review by participating regulatory authorities, within 30 days of receipt. i. Coordinate all MRB activities and associated matters with the ISC Chairperson. j. Ensure that the manufacturer provides the necessary technical and MSG.3 training to MRB members and WG advisors. k. Attend ISC meetings. 1. Ensure that the appropriate regulatory authority is in attendance at all WG meetings. m. Offer advice to the ISC and the WG’s. n. Invite the ISC Chairperson and selected ISC members to the MRB meetings. Par 26 Page 5 ### Page 11 AC 121922A 317197 o. Review reports from previous ISC meetings (if applicable) and from the WG members. p. Discuss potential problem areas and controversy with other regulatory authority management. q. Approve the MRBR, and revisions, IAW established MRBR and revision procedures. 28. MRB MEMBERS. MRB members are expected to perform the following functions: a. Provide guidance to the FAA WG advisors and WG members. b. Direct FAA WG advisors in assigned WG. c. Attend MRB meetings. d. Attend ISC meetings, as invited by the ISC Chairperson. e. Review WG meeting minutes and provide progress reports to the MRB Chairperson before the next scheduled ISC meeting. This review will contain an assessment of WG activities, including a notification of any controversy for potential problem areas. 29. FAA WG ADVISORS. FAA WG advisors are expected to perform the following functions: a. Attend WG meetings and provide advice to the WG members. b. Attend MRB meetings. c. Provide progress reports to the MRB member assigned to the WG before the next scheduled ISC meeting. This report will contain an assessment of WG activities, including notification of any controversy or potential problem NOTE: FAA WG advisors must include FAA engineering/design certification staff. 30. OTHER REGULATORY AUTHORITIES. Other regulatory authorities normally will perform the following functions: a. Participate in the MRB and/or WG activities, as provided by the letter of confirmation between the regulatory authority and the FAA. b. Attend ISC meetings by invitation from the ISC Chairperson and concurrence of the MRB Chairperson. c. Notify the ISC Chairperson, via the MRB Chairperson, of any national regulatory differences before compiling the MRBR proposal. d. Acknowledge approval of the MRBR in the manner outlined in the letter of confirmation, and in the PPH. e. Review WG meeting minutes and provide, to the MRB Chairperson, an assessment or notification of any controversial or potential problem areas before the next .scheduled ISC meeting. NOTE 1: If multiple regulatory authority participation is required, it should be conducted through the use of common standards and joint authority representation. NOTE 2: When the role of the host authority is limited due to the lack of personnel or other reasons, the MRB Chairperson may seek more involvement of other regulatory authorities as MRB members1 WG advisors. NOTE 3: Generic terms or terminology should be used when dealing with various regulatory rule requirements (for example, “Regulations or other national regulatory requirements”). **31. - 35. RESERVED.** Page 6 Par 27 ### Page 12 **317197 AC 121922A CHAPTER 4. MRBR APPROVAL** 36. MRBR APPROVAL PROCESS. The ISC Chairperson forwards the proposed MRBR to the manufacturer’s representative(s), and may invite the manufacturer to discuss the proposal. The manufacturer must present the proposed MRBR, as recommended or with revisions, to the FAA for approval as part of the Instructions for Continued Airworthiness. The manufacturer transmits the proposed MRBR to the MRB Chairperson for review and for approval and for submittal to AFS-300 for concurrence. Normally, the FAA approval process occurs within a time frame of no more than 90 days. Approval by other regulatory authorities will normally occur concurrently with that of the FAA. The manufacturer is responsible for publishing and distributing initial and revised MRBR’s and any supporting documents. 37. OTHER REGULATORY AUTHORITY APPROVAL OF THE MRBR. There may be a need to identify national regulatory differences that are not compatible, acceptable, or applicable to all regulatory authorities. When this condition exists, an appendix to the MRBR may be used to list these differences, with each being approved by the respective regulatory authority. 38. NON-APPROVAL PROCESS OF THE PROPOSED MRBR OR REVISION. The manufacturer shall coordinate non-approval of either the MRBR or revision with the MRB Chairperson, so that the ISC Chairperson may be notified in writing of such action. The non-approval letter shall include the specific reason(s) for the non-approval, and suggested guidance to make the MRBR proposal or revision approval. 39. MRBR OR REVISION IMPLEMENTATION. Air Carriers of the aircraft type should implement the MRBR, or revisions thereto, IAW established procedures. For air carriers of similar aircraft, and dependent on a particular air carrier’s qualifications and overall maintenance experience, adjustments to initial maintenance program intervals may be approved by the air carrier’s corresponding regulatory authority. **40. - 45. RESERVED.** Par 36 Page 7 ### Page 13 AC 121122A 3m97 (THIS PAGE INTENTIONALLY LEFT BLANK) Page 8 Par 36 ### Page 14 **317197 AC 121122A CHAPTER 5. MRBR REVISIONS** 46. ANNUAL REVIEW. Because the MRBR is intended to be an up-to-date document, the manufacturer, the ISC Chairperson, and the MRB Chairperson should conduct a joint review, at least annually, to determine the need for a revision. Results of these reviews should be documented by the MRB Chairperson for inclusion in the MRB historical file. a. Proposed Changes. If needed, the manufacturer and the MRB will convene and evaluate any proposed changes. Proposed changes are submitted with supporting data to the MRB Chairperson. Approval or non-approval of the proposed changes is to be processed in the same manner as outlined for the initial MRBR approval/nonapproval. b. Multiple Approvals. If an MRBR has been approved by more than one regulatory authority, then proposed changes will be evaluated by those approving authorities (as per letter of confirmation) before approval by the FAA. Published revisions to the MRBR shall then be reviewed by the corresponding regulatory authority for possible changes to an air carrier’s maintenance program. **47. - 55. RESERVED.** Par 46 Page 9 ### Page 15 AC 121122A 317197 (THIS PAGE INTENTIONALLY LEFT BLANK) Page 10 P-46 ### Page 16 **317197 AC 121122A CHAPTER 6. RECOMMENDED MRBR FORMAT AND CONTENT** 56. RECOMMENDATIONS. Each MRBR should be entitled “MRB Report,” and at a minimum, should contain the following, as appropriate: a. A Revision Log. b. A List of Effective Pages (including the revision status and corresponding dates). c. A Title Page (containing the title of the MRBR and the report number, if any). d. A Table of Contents. et An Approval Page (containing the following statements): (1) “This report outlines the initial minimum scheduled maintenance/inspection requirements to be used in the development of an approved continuous airworthiness maintenance program for the airframe, engines, systems, and components of the (aircraft make, model, and series).” (2) “The requirements in the report have been developed using Maintenance Steering Group (MSG)- XX logic from the current MSG revision, or an alternative procedure as agreed upon by FAA, ISC, WG, . etc.” (3) “The Federal Aviation Administration (FAA) hereby approves that this report be used by U.S.- certificated air carriers of the (aircraft make, model, and series).” Signed: (Title of approving official) Date: (Insert page for other regulatory authority approval, if applicable) f. An ISC/MRB Personnel Listing (including ISC/MRB personnel, their organizational affiliation, and the capacity in which they serve). g. The MRBR Preamble (The following information should be included in the Preamble of each MRBR): (1) “This report outlines the initial minimum scheduled maintenance/inspection requirements to be used in the development of an approved continuous airworthiness maintenance program for the airframe, engines (on-wing engine only), systems, and components of (aircraft make, model, and series). These MRB requirements are a basis from which each air carrier develops its own continuous airworthiness maintenance program.” (2) “The responsible FAA inspector shall ascertain that all of the applicable scheduled maintenance/ inspection requirements in this report are included in the air carrier’s initial continuous airworthiness maintenance program.” h. Acronyms (All acronyms used in the MRBR should be defined. A listing of acronyms that should be contained in the MRBR are provided in Appendix 2). i. Definitions (Definitions of technical terms should be included in the MRBR. The use of industry accepted definitions, such as those found in ATA MSG documents and World Airlines Technical Operations Glossary, should be used whenever possible). j. Applicability (The MRBR must identify the specific aircraft make, model, and series, and the standard options. New options will be added to the MRBR summary sheets). Par 56 Page 11 ### Page 17 AC 121122A 317197 k. Checks and Intervals (All tasks and their frequencies shall be identified in the MRBR. In certain cases, it may be necessary to establish and include task intervals less than that of an “A” check interval in the MRBR). (1) Further guidance may also be provided in the MRBR regarding the means to escalate the initial minimum scheduled inspection/maintenance intervals to a level higher than that provided as initial intervals in the MRBR. This guidance will be unique to the aircraft. (2) Escalation guidance should take into consideration the content of like checks and their repetitive intervals. A series or sequence of specified checks must be completed and the results found satisfactory before escalation of that type of check. Description, type of checks, and their intervals should be included in this section of the MRBR. P. Maintenance program rules (The following rules should be contained in the MRBR): (1) If there is an escalation procedure contained in the MRBR, the following rule applies: The individual check intervals listed in this report may be escalated following the completion of the required series or sequence of checks and the satisfactory review of check results and approval by the appropriate regulatory authority, or IAW the air carrier’s FAA-approved reliability program. (2) Individual task intervals may be escalated based on satisfactory substantiation by the air carrier, and review and approval by its appropriate regulatory authority, or IAW the air carrier’s FAA-approved reliability program. (3) Service Bulletins may be referenced by number in this report for clarifying the procedural aspects of this program; however, they shall not be used for escalation purposes. (4) Task interval parameters expressed in the MRBR may be converted to an individual air carrier’s desired units, provided this conversion does not result in the air carrier exceeding the initial requirements of the MRBR. (5) The use of nondestructive inspection (NDI) methods, such as “X-ray,” “ultrasonic,” “eddy current,’ ’ and ‘ ‘radio isotope,’ ’ which are approved by the manufacturer, can provide an alternative to the methods prescribed in this report. Each air carrier should notify its regulatory authority of the use of an acceptable alternative method. (6) Within this report, the terms “check” and “inspection” are not intended to imply a level of skill required to accomplish a task. (7) Life-limited parts must be retired IAW the limits established in the engine or aircraft Type Certificate Data Sheets (TCDS) or the Airworthiness Limitations section of the engine or aircraft manufacturer’s Instructions for Continued Airworthiness. (8) After the accumulation of industry service experience, the ISC or MRB Chairpersons may request changes to the requirements of this MRBR. m. System/powerplant program rules (The following are recommended contents of the System Program Rules section of the MRBR): (1) “MSG-3 (Specify the revision) logic was used to develop an on-wing scheduled maintenance program. With the exception of life-limited parts, this process does not normally include detailed off-wing shop maintenance procedures. Off-wing detailed procedures are controlled by individual air carriers and are derived from the air carrier’s reliability program or are IAW the manufacturer’s Instructions for Continued Airworthiness which are required by the Regulations. Page 12 Par 56 ### Page 18 317197 AC 121922A (2) Maintenance Significant Items. (Insert MS1 list.) (3) All MSI’s identified by the manufacturer have been subjected to the MSG.3 analysis. This process has resulted in the identification of maintenance tasks that are contained in this report. Those MSI’s for which a task was not generated during the analysis are identified as follows:” (Insert MS1 listing for which no tasks were identified.) n. Structural program rules (Structural inspection programs (SIP) are developed by the aircraft manufacturer to meet the inspection requirements for damage tolerance. The types of damage considered during program development are environmental deterioration (ED) (corrosion, stress corrosion), accidental, and fatigue. Some forms of ED are age related; therefore, inspections for this type of deterioration are controlled by calendar intervals. These calendar inspections, plus the requirements for detecting other types of ED, and accidental and fatigue damage (ID), are contained in the SIP. The following are recommended contents of the structural program rules section of the MRBR): (1) “All aircraft in an air carrier’s or group of air carrier’s fleet shall be subject to the provisions of this report. These requirements include external and internal inspections, structural sampling and ageexploration programs, corrosion prevention and control programs, and additional supplemental structural inspections that may be required for fatigue-related items. A reliability program shall not be used to escalate the inspection interval, or delete the task, on any structural inspection item listed in the Airworthiness Limitations section. Initial check intervals for the SIP are expressed in calendar time, flight cycles, or flight hours. No repeat inspection interval shall be escalated until at least one aircraft in an air carrier’s or group of air carrier’s fleet has been inspected within the initially defined interval listed in the MRBR. (2) Structural inspection limitations listed in the aircraft manufacturer’s Airworthiness Limitations section will be referenced in the MRBR by document number.” (Insert SSI sheets.) o. Zonal program rules (The Zonal Inspection Program (ZIP) provides consolidation of a number of general visual inspection (GVI) tasks for each zone. A zonal inspection may include GVI tasks derived from MS1 and SSI. An MWSSI task that is in the ZIP must be cross-referenced, in the supporting documentation, as a zonal item; likewise, the zonal item must be cross referenced as an MWSSI task to ensure content and accountability. The following are recommended contents of the Zonal Program Rules section of the MRBR:) (1) “The ZIP contains a series of GVI tasks. Detailed and special detailed inspections (DI) are not to be contained in the ZIP. Zonal inspection requirements apply only to zones. (2) Access to zones should be easily accomplished and should not require the use of special tools. Normally, the inspection aids to be used are a flashlight and/or inspection mirror. The entire visible contents of the zone must be inspected for obvious damage, security of installation, and general condition including corrosion and leaks. (3) The following zones do not contain system installations but receive adequate surveillance from other maintenance or structural inspections tasks. Accordingly, these zones are not specified in the inspection requirements presented in the ZIP.” (Insert listing of the zones not specified in the ZIP.) (Insert zonal inspection sheets.) p. Appendixes. Par 56 Page 13 ### Page 19 AC 121122A 3l7D7 (1) Aircraft zones. (2) National regulatory differences as mandated by other regulatory authorities. (Each shall be accepted by the respective authority.) (3) Acronyms. (4) Definitions. (5) Other, as applicable. **57. - 65. RESERVED.** Page 14 Par 56 ### Page 20 3m97 AC 121922A Appendix 1 APPENDIX 1. POLICY AND PROCEDURES HANDBOOK (PPH) This appendix contains guidance to be used by the aircraft manufacturer, the ISC, and MRB Chairpersons during the development and review of the PPH. The following is an outline which contains items that should be included in the PPH. I. Recommended Contents A. B . C. D. E. F. G. H. I. J. K. L. M. N. 0. Introduction (identify MSG Baseline) Table of Contents Revision Control Organizational Outline (including the number and type of WG’s) and Duties and Responsibilities of Personnel **1. ISC** 2. Manufacturer(s) 3. WG Members 4. MRB Members and Advisors 5. Other Regulatory Authority Participants Technical and Maintenance Development Training for ISC and WG Members and FAA MRB Advisors) Program Timetables/Meeting Schedules Proposed Check Interval Parameters, if any, (for analysis and planning purposes) Analysis/Procedures to be Utilized (such as MSG-3) Forms that identify questions, actions, and transfers that may occur during WG activities Documentation of Meetings and General Administrative Procedures (The PPH should state that all formal meetings will be documented and that the minutes will be distributed by either the ISC Chairperson or a designee.) Acronyms Definitions Appendixes MSG Document Other, as applicable ### Page 21 AC 121922A Appendix 1 3m97 (THIS PAGE INTENTIONALLY LEFT BLANK) Page 2 ### Page 22 317197 AC 121122A Appendix 2 APPENDIX 2. SUGGESTED ACRONYM LISTING FOR THE MRBR The following is a recommended listing of acronyms which may be contained in the acronym section of each MRBR. AC Advisory Circular AD Accidental Damage AEG Aircraft Evaluation Group AEP Age Exploration Program ATA Air Transport Association of America CAM Canadian Airworthiness Manual CMR Certification Maintenance Requirement DI Detailed Inspection DTR Damage Tolerance Rating ED Environmental Deterioration FAA Federal Aviation Administration FAR Federal Aviation Regulations FD Fatigue Damage FMEA Failure Mode and Effects Analysis GVI General Visual Inspection ISC Industry Steering Committee JAA Joint Aviation Authorities JAR Joint Airworthiness Requirement MEA Maintenance Engineering Analysis MEL Minimum Equipment List MFG Manufacturer MMEL Master Minimum Equipment List MPP Maintenance Program Proposal MRB Maintenance Review Board MRBR Maintenance Review Board Report MRBPB Maintenance Review Board Policy Board MSC Maintenance Steering Committee MSG.1 Maintenance Steering Group - 1st Task Force MSG.2 Maintenance Steering Group - 2nd Task Force MSG.3 Maintenance Steering Group - 3rd Task Force MS1 Maintenance Significant Item MTBF Mean Time Between Failure MTBUR Mean Time Between Unscheduled Removal ND1 Nondestructive Inspection NDT Nondestructive Test PPH Policy and Procedures Handbook SD1 Special Detailed Inspection SID Supplemental Inspection Document SIP Structural Inspection Program SSI Structural Significant Item SSID Supplemental Structural Inspection Document TBD To Be Determined WG Working Group ZIP Zonal Inspection Program Page 1 ### Page 23 AC 121922A Appendix 2 (THIS PAGE INTENTIONALLY LEFT BLANK) Page 2 ### Page 24 AC 121122A 3Rlw Appendix 3 APPENDIX 3. SCHEDULED MAINTENANCE TASK DEVELOPMENT start of MRBR process d r-4Manufacturer Mentifbs ISC I members for working group I hASI’s and SSl’s are anatyzed ISC group presents proposal to aircraft manufacturer Manufacturer presents maintenance task intenral proposal to FM MRB . I-- Nomanufacturer Page 1 ### Page 25 (OCR) AC 121-22A Appendix 3a 3/7/97 APPENDIX 3а. SCHEDULED MAINTENANCE TASK DEVELOPMENT and INSTRUCTIONS for CONTINUED AIRWORTHINESS PROCESS Manufacturer's Activities Pm-Type Certificate MRB approved FAA AEG, & Certification Advisors Title 14 Manufacture (Member- ISC of the WG) Code of Manufacturer / MRB Federal (Member ISC WG) ALL Vendors ISC Chairman (ISC Co-Chairman) TC Applicant Report Proposal AC 121.22A Regulations (14CFR) Parts ALL Customers 91 (Member ISC WG) ACO & AEG Pm-Type Certificate Activities 121 AEG / MRB Chair *Maintenance Manual MRB Approved AEG / MRB "Scheduling In fomation ACO Type Certification *Troubleabooting Information Board *Structural Diagrams End Result *Special Inspectic TC Boar 135 CMR'* (AC Approved Instructions for Continued Section 25,571 Part 23 & Soction 23 25.1529 Amendix G & H Part 27 & Soction "Certification Regulations Requirements 29.1529 Section 31.82 Appendix A Part 33 & Soction 35.4 Appendix A NOTE Work Cards Wiring Diagrams When constructing the Structural Ropeir Manuals Airworthinoss, thos Mustrated Parts Catalog: Cort. Maintenance Regmu to be considered: ilome, wben available, aro App. MRB Report Reqmts. Maint Planning Documents Page 2 ### Page 26 U.S. Department of Transportation Federal Aviation Administration 800 Independence Ave., Washington, D.C. 20591 S.W. Official Penalty ,Business for Private Use $300 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.