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Aeronautical Bulletin 7E Future Link Future Link

	The founder of Airworthy.US began rebuilding and maintaining airplanes in 1965 in exchange for flying lessons. He later earned a living as a flight instructor, a commuter airline pilot, and as a licensed Airframe & Powerplant Mechanic prior to working in various capacities for aerospace manufacturers including Bendix, Sundstrand, Textron Lycoming, Douglas Aircraft Company and Boeing.
	MAINTAINABILITY AND SUPPORT REQUIREMENTS I. Under the Federal Aviation Act of 1958, the FAA has been mandated to perform two basic missions: To foster air commerce and, To promote safety - of people in aircraft, of other aircraft in the same airspace, and of people and property on the ground beneath the aircraft's flight path.   A. Within that framework, the FAA has three main priorities: 1. Continued Airworthiness; 2. Rulemaking and Enforcement, and; 3. Certification.   II. An airline's primary business is to provide the service of transporting passengers and freight in aircraft. A. The airline's priorities, concerned with passenger well being, compliance with regulatory requirements, and competitive pricing include achieving: 1. Absolute Safety of flight, 2. 100% Dispatch Reliability, and 3. Lowest possible Cost of Ownership, including Acquisition cost, fuel, crew, and; Direct Maintenance Cost (DMC).   III. There are two major operational elements of commercial airlines; engineering & maintenance, and flight operations. Of the two, engineering & maintenance requires the greater support resources, from the airline and from the airframe manufacturer, in terms of manpower, equipment, and facilities.   A commercial transport category aircraft, at time of certification, meets all applicable requirements based on available technology, accepted engineering practices, and regulatory requirements. As aircraft are designed to fly longer, higher, faster, carry more passengers and freight, and are constructed using materials and processes developed specifically to support such advances, in an environment that is itself changing, the effects on the continuing airworthiness of the aircraft are also changing. Add to that the goal of attaining the utmost in efficiency of the airframe/engine combination, the ongoing cost-cutting in the industry, and the moral and ethical mandate to pursue absolute safety of flight, and the increasing significance of all aspects of maintenance becomes apparent.   Flight operations traditionally has been the main focus of safety and efficiency. Conspicuous by its absence has been the role that maintenance is capable of playing in improving overall efficiency and in enhancing safety of flight.   Maintenance, however, has been recognized recently for its importance. Federico Pena, then Secretary of Transportation, and David Hinson, then FAA Administrator, at a Washington, D.C. press conference unveiled the Aviation Safety Action Plan (ASAP) on February 9, 1995. Among other things, ASAP would focus more attention on maintenance. The FAA was to propose expanding the 1995 FAA strategic plan to develop a Maintenance Resource Management (MRM) program based on the successful Crew Resource Management (CRM) models. That press conference was a fulfillment of a promise made at a summit 30 days earlier, on January 9, the theme of which was "Zero Accidents - The Challenge". (Ref. Airline Pilot, April 1995)   Today's maintenance professional, whether operator or manufacturer, needs to have a broad aviation background and an appreciation of the fact that the industry is evolving and changing. The importance, for example, of the initial scheduled maintence program and the Instructions for Continued Airworthiness as source documents for the operators cannot be overemphasized. Closely related is the fact that in today's increasingly competitive market, a major discriminator for the prospective buyer is the maintainability of the product and its affect on the DMC.
	PART I REGULATORY REQUIREMENTS TO SUPPORT TRANSPORT CATEGORY AIRCRAFT   NOTE: The specific regulations, where they differ from those for all aircraft, are for Transport Category Airplanes (14CFR Part 25), but there are similar requirements for all aircraft.   I. TYPE CERTIFICATE (all aircraft): A. 14CFR section 21.41 defines the type certificate: Each type certificate is considered to include: 1. The type design (ref. 21.31); 2. The operating limitations (ref. Part 25, Subpart G, 25.1501 - 25.1587, including 25.1529); 3. The certificate data sheet: 4. The applicable sections of this subchapter with which the Administrator records compliance, and; 5. Any other conditions or limitations prescribed for the product in this subchapter.   B. TYPE DESIGN: 14CFR section 21.31 states that the type design for transport category aircraft consists of: (a) The drawings and specifications, and a listing of those drawings and specifications, necessary to define the configuration and the design features of the product shown to comply with the requirements of that part of this subchapter applicable to the product; (b) Information on dimensions, materials, and processes necessary to define the structural strength of the product; (c) The Airworthiness Limitations section of the Instructions for Continued Airworthiness (ref. sections 21.50, 25.571, 25.1529).   C. OPERATING LIMITATIONS: Part 25, Subpart G - Operating Limitations and Information, establishes, and requires the availability of operating limitations. Included in Subpart G (25.1501-25.1587) is 25.1529. 1. 14CFR section 25.1529 Instructions for Continued Airworthiness: a. "The applicant must prepare Instructions for Continued Airworthiness in accordance with Appendix H to this part that are acceptable to the Administrator."   II. INSTRUCTIONS FOR CONTINUED AIRWORTHINESS (Appendix H to Part 25) H25.1. General (a) This appendix specifies requirements for the preparation of Instructions for Continued Airworthiness as required by sect. 25.1529. (b) The Instructions for Continued Airworthiness for each airplane must include the Instructions for Continued Airworthiness for each engine and propeller (hereinafter designated "products"), for each appliance required by this chapter, and any required information relating to the interface of those appliances and products with the airplane. (c) The applicant must submit to the FAA a program to show how changes to the Instructions for Continued Airworthiness made by the applicant or by the manufacturers of products and appliances installed in the airplane will be distributed. H25.2. Format (a) The Instructions for Continued Airworthiness must be in the form of a manual or manuals as appropriate for the quantity of data to be provided. (b) The format of the manual or manuals must provide for a practical arrangement. H25.3. Content The content of the manual or manuals must be prepared in the English language. The Instructions for Continued Airworthiness must contain the following manuals or sections, as appropriate, and information: (a) Airplane maintenance manual or section. (1) Introduction information... (2) A description of the airplane and its systems and installations including its engines, propellers, and appliances. (3) Basic control and operation information... (4) Servicing information... (b) Maintenance instructions. (1) Scheduling information for each part of the airplane and its engines, auxiliary power units, propellers, accessories, instruments, and equipment that provides the recommended periods at which they should be cleaned, inspected, adjusted, tested, and lubricated, and the degree of inspection, the applicable wear tolerances, and the work recommended at these periods. (This is the source requirement for providing the FAA with an initial scheduled maintenance/inspection program. (See Part II, following)) . ...The recommended overhaul periods and necessary cross references to the Airworthiness Limitations section of the manual must also be included. In addition, the applicant must include an inspection program that includes the frequency and extent of the inspections necessary to provide for the continued airworthiness of the airplane. (2) Troubleshooting information... (3) Information describing the order and method of removing and replacing products and parts... (4) Other general procedural instructions including procedures for system testing during ground running, symmetry checks, weighing, and determing the center of gravity, lifting, shoring, and storage limitations. (c) Diagrams of structural access plates and information needed to gain access for inspections when access plates are not provided. (d) Details for the application of special inspection techniques including radiographic and ultrasonic testing where such processes are specified. (e) Information needed to apply protective treatments to the structure after inspection. (f) All data relative to structural fasteners such as identification, discard recommendations, and torque values. (g) A list of special tools needed. H25.4 Airworthiness Limitations section. (14CFR section 25.571, Damage-tolerance and fatigue evaluation of structure, requires that an evaluation of the strength, detail design, and fabrication must be performed and must show that catastrophic failure due to fatigue, corrosion (environmental), or accidental damage, will be avoided throughout the operational life of the airplane. Further, based on the evaluations, inspections or other procedures must be established as necessary to prevent catastrophic failure,and must be included in the Airworthiness Limitations section of the Instructions for Continued Airworthiness required by section 25.1529.) The Instructions for Continued Airworthiness must contain a section titled Airworthiness Limitations that is segregated and clearly distinguishable from the rest of the document. This section must set forth: 1.) each mandatory replacement time, 2.) structural inspection interval, and 3.) related structural inspection procedure approved under sect. 25.571...This section must contain a legible statement in a prominent location that reads: "The Airworthiness Limitation section is FAA approved and specifies maintenance required under sections 43.16 and 91.403 of the Federal Aviation Regulations unless an alternative program has been FAA approved."   III. CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS A. 14CFR section 21.50 requires the holder of design approval to furnish at least one set of complete Instructions for Continued Airworthiness, prepared in accordance with FAR section 25.1529 (for transport category aircraft) to the owner of each type of aircraft upon its delivery, or upon issuance of the first standard airworthiness certificate for the affected aircraft, whichever occurs later, and thereafter make those instructions available to any other person required by this chapter with any of the terms of these instructions. In addition, changes to the Instructions for Continued Airworthiness shall be made available to any person required by the FARs to comply with any of those instructions.   PART II MAINTENANCE PROGRAM DEVELOPMENT I. SOURCE REQUIREMENTS A. The specific requirement for preparing an initial scheduled maintenance/inspection program is found in Appendix H to Part 25, Instructions for Continued Airworthiness, paragraph H25.3, (b) (1), see Part I, item III, above. B. FAA Advisory Circular AC No. 121-22A "provides guidelines which may be used in the development and approval of initial maintenance/inspection requirements for a derivative or newly type-certificated transport category aircraft and its powerplants." 1. MAINTENANCE REVIEW BOARD (MRB). When a transport type certification project is undertaken, the airframe designer/manufacturer applies to the FAA Aircraft Certification Office (ACO) for a type certificate, or a major change to an existing type certificate, the FAA Aircraft Evaluation Group (AEG) manager in the controlling FAA Directorate will assign a qualified specialist to assume the responsibility of MRB chairman, except MRB members assigned to the engine/propeller functions, who will be selected by the manager of the FAA's New England Region's Engine/Propeller AEG. 2. INDUSTRY STEERING COMMITTEE (ISC). DAC or ISC is responsible for formally notifying the manager of the AEG of the controlling directorate of its intention to develop a proposal for establishing initial maintenance/inspection requirements for new, or derivative, aircraft and powerplants. The ISC activities should be coordinated with the MRB chairman. The ISC should be composed of members from a representative number of operators and airframe and engine manufacturers. The ISC establishes maintenance program policy, directs the activities of the working groups, and prepares the MRB report proposal. (ref. AC 121-22A, Ch. 3., item 22.) The MRB report proposal, once approved by the FAA, become the base or framework around which each operator develops his own individual maintenance program. An operator's total maintenance program will be approved by the assigned Principal Maintenance Inspector (PMI). 3. MAINTENANCE STEERING GROUP (MSG) Maintenance program development dates back to Aeronautical Bulletin 7E of May 15, 1930 (see "Aeronautical Bulletin 7E" link at top right, or page at bottom). The evolution has gone from individual operator's proposing their unique maintenance programs to a process where the FAA and industry work together to formulate initial scheduled maintenance/inspection requirements. The Air Transport Association of America (ATA) and industry developed Handbook MSG-1, Maintenance Evaluation and Program Development, in 1968, for developing a maintenance program for the B-747. MSG-1 was updated and made universally applicable. MSG-2, Airline/Manufacturer Maintenance Program Planning Document, was the result of the update. In 1979 MSG-2 was reviewed and various areas were identified as candidates for improvement. The active participation and combined efforts of the FAA, CAA/UK, AEA, U.S. and European aircraft and engine manufacturers, U.S. and foreign airlines, and the U.S. Navy generated the document, MSG-3 Airline/Manufacturer Maintenance Program Development Document, issued September 30, 1980. Revision 1 to MSG-3 was approved by the FAA in 1988 for the development of today's and future aircraft and powerplant MRB report. C. MSG-3, Airline/Manufacturer MAINTENANCE PROGRAM DEVELOPMENT DOCUMENT 1. MSG-3 outlines the general organization and decision processes for determining scheduled maintenance requirements initially projected for the life of aircraft and/or powerplant which will be acceptable to the regulatory authorities, the operators, and the manufacturers. The remaining maintenance, i.e. non-scheduled or non-routine maintenance, consists of maintenance actions to correct discrepancies noted during scheduled maintenance tasks, other non-scheduled maintenance, normal operation, or data analysis. 2. The Industry Steering Committee (ISC) should see that the MSG-3 process identifies 100% accountability for all Maintenance Significant Items (MSIs, see 4.a.iii., below) and Structural Significant Items (SSIs, see 4.b.ii., below), whether ir not a task has been derived from the analysis. 3. The objectives of the maintenance program are: a. To ensure realization of the inherent safety and reliability levels of the equipment; and b. To restore safety and reliability to their inherent levels when deterioration has occurred. Another way of saying the above: To determine the maintenance tasks required to preclude significant failures of systems and structures, and to maintain the aircraft in an airworthy condition. Also, the maintenance program will determine the intervals at which specific maintenance tasks are to be performed. 4. The MSG-3 process is broken down into three main parts: a. Aircraft Systems/Powerplant (including components & APUs) Analysis Method (see also FAR 25.1309 Equipment, systems, and installations) i. Based on the item's functional failures, effect of the failure, and failure causes ii. Identify Aircraft's significant systems and components iii. Maintenance Significant Items (MSIs) are those items identified by the manufacturer whose failure: a) could affect safety on the ground or in flight, b) could be undetectable or are unlikely to be detected during operations (latent), and/or c) could have significant operational impact, and/or d) could have significant economic impact b. Aircraft Structural Maintenance Program Development i. The structural maintenance program is designed to relate the scheduled maintenance tasks to the effect of structural damage remaining undetected. Each structural item is evaluated in terms of: a) Its significance to continuing airworthiness; b) Its susceptibility to any form of damage (accidental, environmental, fatigue); c) The degree of difficulty involved in detecting such damage. ii. Aircraft Structure defined per MSG-3 document (see also FAR 25.571): ...all load carrying members including wings, fuselage, empennage, engine mountings, landing gear, flight control surfaces, and related points of attachment. a) A Significant Structural Item (SSI) (primary) is any detail, element, or assembly, which contributes significantly to carrying flight, ground, pressure, or control loads, and whose failure could affect the structural integrity necessary for the safety of the aircraft. b) Other Structure (secondary) is that which is judged not to be an SSI. c. Zonal Inspection Program i. Requires a summary review of each zone of the aircraft and normally occurs as the analysis of structures, systems, and powerplants are being concluded. In cases where a general visual inspection is required to assess degradation, the zonal inspection is an appropriate method ii. Procedure: a) Divide the aircraft externally and internally into zones as defined in ATA 100. b) Prepare a task listing work sheet for each zone including location, description, access notes, etc. c) During analysis of systems, structures, and powerplants, list any general visual inspections which could be conducted as part of the zonal inspection program. d) Include the interval from the original analyses on the zone work sheet. e) As the analysis covering items in a zone are completed, the zone should be reviewed to consolidate inspection requirements and assign accomplishment intervals. Document in the work sheets any System/Powerplant or Structural general visual inspections replaced by the zonal inspection tasks. iii. Zonal Task Intervals: Accomplishments are based on hardware, susceptibility to damage, the amount of activity in the zone, and operator and manufacturer experience with similar systems, powerplants, and structures. When possible, intervals should correspond to those selected for targeted scheduled maintenance checks.   PART III MAINTAINABILITY I. OBJECTIVE A. The challenge and a maintainability program is to enhance and improve maintainability of the aircraft. 1. Maintainability is best served when it takes a holistic approach, treating maintenance as a whole system rather than seemingly unrelated parts. Maintainability needs to be integrated into a coherent program where every opportunity to address and improve maitainability will be siezed. 2. The opportunity to enhance and improve maintainability occurs throughout an aircraft's entire life cycle, i.e. design, certification, manufacturing, and post delivery aircraft maintenance operation.   II. PROCESS A. The top level process begins with two questions regarding each defined maintenance task; 1. Is the task necessary?, and if so, 2. What can be done to make the defined task easier, less time consuming, less dependent on special tools, equipment, and processes; in general what will make the accomplishment of the task more efficient, and thereby less costly? B. A maintenance task is composed of one or several major elements; inspection, test, servicing, replacement, or repair, the purpose of which: 1. Ensures the safety and reliability of systems, equipment, and structure (inspections and tests); 2. Identifies deterioration in safety and reliability; and 3. Restores safety and reliability to their inherent levels when deterioration has occurred (servicing, replacing, or repairing the deteriorated system, equipment, or structure).   III. PROCEDURE A. The process is applied to the following elements: 1. Maintenance tasks required by 14CFR sections 25.571 for Airworthiness Limitation items (ALIs), and 25.1309 for Certification Maintenance Requirements (CMRs) will be identified. a. i. Review each CMR and ALI for familiarization and concurrence (answer the first maintainability question, "Is the task necessary?"), and to; ii. Establish the mandatory replacement time, inspection interval, and inspection procedure (answer the second maintainability question, "What can be done to make the defined task easier, less time consuming, less dependent on special tools, equipment, and processes; in general what will make the accomplishment of the task more efficient, and thereby less costly?") for each CMR and ALI. b. Other maintenance tasks may be added in the development of the initial scheduled maintenance program. 2. Master Minimum Equipment List (MMEL): a. The type certificate holder is responsible for developing a list of equipment and functions which need not be operative for safe flight and landing based on stated compensating precautions that should be taken, e.g. operational or time limitations, or flight crew or ground crew checks. This list is allowed in accordance with 14CFR section 25.1309 and becomes the basis for the Master Minimum Equipment List (MMEL). The TC holder develops the related MEL Procedures Manual. 3. Maintenance Manuals, following, will be reviewed, and the maintainability question will be asked; "What can be done to make the defined tasks easier, less time consuming, less dependent on special tools, equipment, and processes, in general what will make the accomplishment of the task more efficient, and thereby less costly?": a. The Maintenance Manual and changes thereto. b. Vendor/supplier Component Maintenance Manuals and changes thereto . c. Any other manuals necessary in the pursuit of improving maintainability. 4. Engineering/Design Drawings will be reviewed: a. Analyze systems in accordance with maintainability enhancement objectives in accordance with established standards/guidelines b. Approve/sign-off as is, or c. Recommend changes necessary to enhance maintainability. 5. Physical review - M&SR will: a. Observe selected procedures during manufacture/assembly. b. Participate in maintainability demonstration/manual verification at TC holder, and at Vendors/Suppliers. c. Participate in maintainability investigations at airline customer's facility. d. Monitor fleet maintainability issues and concerns, and e. Recommend improvements/enhancements whenever feasible.

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