Aviation Maintenance

Aircraft maintenance is a pilot and aviation maintenance technician task that ensures the safety of aviation operations.


Introduction

Introduction
  • Preventive maintenance is regarded as simple or minor preservation operations and the replacement of small standard parts, not involving complex assembly operations
  • Maintenance, Preventive Maintenance, Rebuilding, and Alteration, the holder of a pilot certificate issued under 14 CFR Part 61 may perform specified preventive maintenance on any aircraft owned or operated by that pilot, as long as the aircraft is not used under 14 CFR Part 121, 127, 129, or 135. This pamphlet provides information on authorized preventive maintenance

Preventative Maintenance Defined

Preventative Maintenance Defined
  • In FAA terms, there are a few different types of maintenance ("PARM"):
    • Preventative Maintenance
    • Alterations
    • Repairs
    • Maintenance

  • Preventative Maintenance:

    • Preventative maintenance is what concerns us as pilots while maintenance, alterations, and repairs are considered higher level echelons, discussed below

  • Alterations & Repairs:

    • Repairs and alterations are classified as either major or minor
    • 14 CFR part 43, appendix A, describes the alterations and repairs considered major
    • Major repairs or alterations shall be approved for return to service on FAA Form 337, Major Repair and Alteration, by an appropriately rated certificated repair station, an FAA-certificated A&P mechanic holding an IA, or a representative of the Administrator

    • Major Repairs and Alterations:

      • Major Repairs:
        • Major repair means a repair:
          • That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
          • That is not done according to accepted practices or cannot be done by elementary operations
      • Major Alteration:
        • Major alteration, means an alteration not listed in the aircraft, aircraft engine, or propeller specifications:
          • That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
          • That is not done according to accepted practices or cannot be done by elementary operations

    • Minor Repairs and Alterations:

      • Minor repairs and minor alterations may be approved for return to service with a proper entry in the maintenance records by an FAA-certificated A&P mechanic or an appropriately certificated repair station
      • For modifications of experimental aircraft, refer to the operating limitations issued to that aircraft. Modifications in accordance with FAA Order 8130.2, Airworthiness Certification of Aircraft and Related Products, may require the notification of the issuing authority

  • Maintenance:

    • Maintenance are those actions required above that of preventative maintenance of which a qualified A&P is required

Preventative Maintenance Items

Preventative Maintenance Items
  • Preventive maintenance is limited to the following work (listed in FAR 43.3, Appendix A[c]), provided it does not involve complex assembly operations:
    • Removal, installation, and repair of landing gear tires
    • Replacing elastic shock absorber cords on landing gear
    • Servicing landing gear shock struts by adding oil, air, or both
    • Servicing landing gear wheel bearings, such as cleaning and greasing
      • Disassembling and cleaning the landing gear, replacing gaskets, and greasing appropriate parts will mitigate corrision, the leading caues of replacing wheels
    • Replacing defective safety wiring or cotter keys
    • Lubrication not requiring disassembly other than removal of nonstructural items such as cover plates, cowlings, and fairings
    • Making simple fabric patches not requiring rib stitching or the removal of structural parts or control surfaces. In the case of balloons, the making of small fabric repairs to envelopes (as defined in, and in accordance with, the balloon manufacturers' instructions) not requiring load tape repair or replacement
    • Replenishing hydraulic fluid in the hydraulic reservoir
    • Refinishing decorative coating of fuselage, balloon baskets, wings tail group surfaces (excluding balanced control surfaces), fairings, cowlings, landing gear, cabin, or cockpit interior when removal or disassembly of any primary structure or operating system is not required
    • Applying preservative or protective material to components where no disassembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices
    • Repairing upholstery and decorative furnishings of the cabin, cockpit, or balloon basket interior when the repairing does not require disassembly of any primary structure or operating system or interfere with an operating system or affect the primary structure of the aircraft
    • Making small simple repairs to fairings, nonstructural cover plates, cowlings, and small patches and reinforcements not changing the contour so as to interfere with proper air flow
    • Replacing side windows where that work does not interfere with the structure or any operating system such as controls, electrical equipment, etc
    • Replacing safety belts
    • Replacing seats or seat parts with replacement parts approved for the aircraft, not involving disassembly of any primary structure or operating system
    • Trouble shooting and repairing broken circuits in landing light wiring circuits
    • Replacing bulbs, reflectors, and lenses of position and landing lights
    • Replacing wheels and skis where no weight and balance computation is involved
    • Replacing any cowling not requiring removal of the propeller or disconnection of flight controls
    • Replacing or cleaning spark plugs and setting of spark plug gap clearance
    • Replacing any hose connection except hydraulic connections
    • Replacing prefabricated fuel lines
    • Cleaning or replacing fuel and oil strainers or filter elements
      • Frequent oil analysis used in conjunction with changes ensures trends can be measured and abnormalies found
      • Pilots are of course permitted to add oil however, adding oil is not formally considered preventative maintenance and therefore does not need to be logged
    • Replacing and servicing batteries
    • Cleaning of balloon burner pilot and main nozzles in accordance with the balloon manufacturer's instructions
    • Replacement or adjustment of nonstructural standard fasteners incidental to operations
    • The interchange of balloon baskets and burners on envelopes when the basket or burner is designated as interchangeable in the balloon type certificate data and the baskets and burners are specifically designed for quick removal and installation
    • The installations of anti-misfueling devices to reduce the diameter of fuel tank filler openings provided the specific device has been made a part of the aircraft type certificate data by the aircraft manufacturer, the aircraft manufacturer has provided FAA-approved instructions for installation of the specific device, and installation does not involve the disassembly of the existing tank filler opening
    • Removing, checking, and replacing magnetic chip detectors
    • The inspection and maintenance tasks prescribed and specifically identified as preventive maintenance in a primary category aircraft type certificate or supplemental type certificate holder's approved special inspection and preventive maintenance program when accomplished on a primary category aircraft provided:
      • They are performed by the holder of at least a private pilot certificate issued under part 61 who is the registered owner (including co-owners) of the affected aircraft and who holds a certificate of competency for the affected aircraft (1) issued by a school approved under FAR 147.21(e) of this chapter; (2) issued by the holder of the production certificate for that primary category aircraft that has a special training program approved under FAR 21.24 of this subchapter; or (3) issued by another entity that has a course approved by the Administrator; and
      • The inspections and maintenance tasks are performed in accordance with instructions contained by the special inspection and preventive maintenance program approved as part of the aircraft's type design or supplemental type design
    • Removing and replacing self-contained, front instrument panel-mounted navigation and communication devices that employ tray-mounted connectors that connect the unit when the unit is installed into the instrument panel, (excluding automatic flight control systems, transponders, and microwave frequency distance measuring equipment (DME)). The approved unit must be designed to be readily and repeatedly removed and replaced, and pertinent instructions must be provided. Prior to the unit's intended use, and operational check must be performed in accordance with the applicable sections of part 91 of this chapter

Who Can Perform Preventative Maintenance

Who Can Perform Preventative Maintenance
  • Except as provided in this section and FAR 43.17, no person may maintain, rebuild, alter, or perform preventive maintenance on an aircraft, airframe, aircraft engine, propeller, appliance, or component part to which this part applies. Those items, the performance of which is a major alteration, a major repair, or preventive maintenance, are listed in appendix A
  • The holder of a mechanic certificate may perform maintenance, preventive maintenance, and alterations as provided in Part 65 of this chapter
  • The holder of a repairman certificate may perform maintenance, preventive maintenance, and alterations as provided in part 65 of this chapter
  • A person working under the supervision of a holder of a mechanic or repairman certificate may perform the maintenance, preventive maintenance, and alterations that his supervisor is authorized to perform, if the supervisor personally observes the work being done to the extent necessary to ensure that it is being done properly and if the supervisor is readily available, in person, for consultation. However, this paragraph does not authorize the performance of any inspection required by Part 91 or Part 125 of this chapter or any inspection performed after a major repair or alteration
  • The holder of a repair station certificate may perform maintenance, preventive maintenance, and alterations as provided in Part 145 of this chapter
  • The holder of an air carrier operating certificate or an operating certificate issued under Part 121 or 135, may perform maintenance, preventive maintenance, and alterations as provided in Part 121 or 135
  • Except for holders of a sport pilot certificate, the holder of a pilot certificate issued under part 61 may perform preventive maintenance on any aircraft owned or operated by that pilot which is not used under part 121, 129, or 135 of this chapter. The holder of a sport pilot certificate may perform preventive maintenance on an aircraft owned or operated by that pilot and issued a special airworthiness certificate in the light-sport category
  • Notwithstanding the provisions of paragraph (g) of this section, the Administrator may approve a certificate holder under Part 135 of this chapter, operating rotorcraft in a remote area, to allow a pilot to perform specific preventive maintenance items provided:
    • The items of preventive maintenance are a result of a known or suspected mechanical difficulty or malfunction that occurred en route to or in a remote area;
    • The pilot has satisfactorily completed an approved training program and is authorized in writing by the certificate holder for each item of preventive maintenance that the pilot is authorized to perform;
    • There is no certificated mechanic available to perform preventive maintenance;
    • The certificate holder has procedures to evaluate the accomplishment of a preventive maintenance item that requires a decision concerning the airworthiness of the rotorcraft; and
    • The items of preventive maintenance authorized by this section are those listed in paragraph (c) of appendix A of this part
  • Notwithstanding the provisions of paragraph (g) of this section, in accordance with an approval issued to the holder of a certificate issued under part 135 of this chapter, a pilot of an aircraft type-certificated for 9 or fewer passenger seats, excluding any pilot seat, may perform the removal and reinstallation of approved aircraft cabin seats, approved cabin-mounted stretchers, and when no tools are required, approved cabin-mounted medical oxygen bottles, provided:
    • The pilot has satisfactorily completed an approved training program and is authorized in writing by the certificate holder to perform each task; and
    • The certificate holder has written procedures available to the pilot to evaluate the accomplishment of the task
  • A manufacturer may:
    • Rebuild or alter any aircraft, aircraft engine, propeller, or appliance manufactured by him under a type or production certificate;
    • Rebuild or alter any appliance or part of aircraft, aircraft engines, propellers, or appliances manufactured by him under a Technical Standard Order Authorization, an FAA-Parts Manufacturer Approval, or Product and Process Specification issued by the Administrator; and
    • Perform any inspection required by part 91 or part 125 of this chapter on aircraft it manufactured under a type certificate, or currently manufactures under a production certificate
  • Updates of databases in installed avionics meeting the conditions of this paragraph are not considered maintenance and may be performed by pilots provided:
    • The database upload is:
      • Initiated from the flight deck;
      • Performed without disassembling the avionics unit; and
      • Performed without the use of tools and/or special equipment
    • The pilot must comply with the certificate holder's procedures or the manufacturer's instructions
    • The holder of operating certificates must make available written procedures consistent with manufacturer's instructions to the pilot that describe how to:
      • Perform the database update; and
      • Determine the status of the data upload
    • As of Jan. 28, 2013, updating databases for self-contained, front-panel, or pedestal-mounted GPS units is a non-maintenance task

How to Conduct Preventative Maintenance

How to Conduct Preventative Maintenance
  • To conduct preventative maintenance, consider the acronym "MC-PLT:"
  • Ensure you have (and use) the approved manuals
  • Maintenance must be performed with the same craftsmanship
  • Ensure you have (and use) the approved parts
  • Must be logged appropriately
  • Ensure you have (and use) the approved tools

Logging Preventative Maintenance

Logging Preventative Maintenance
  • Logging preventative maintenance in the appropriate logbook:
    • Airframe maintenance should go in the airframe logbook
    • Powerplant maintenance should go in the powerplant logbook
    • In those instances where it may not be clear (i.e., exhaust system), log them in both as the safest bet
  • As required by FAR 43.9, preventive maintenance must be recorded by entering the following information into the maintenance record of the item worked on:
    • A description of the work, such as "changed oil (Shell Aero-50) at 2,345 hours"
      • The description should indicate what was done and how it was done
      • This is normally quite simple for preventive maintenance; however, if the description is extensive, it is acceptable to reference documents containing that description
      • These may be manufacturer's manuals, ACs, or other documents or references containing acceptable data
      • If documents other than types commonly used are referenced, the document should be included in the maintenance record
    • The date of completion of the work performed
      • Time since major overhaul is sometimes recommended
    • The pilot's name, signature, certificate number, and type of certificate held
      • Affixing a signature to the entry, which describes the work accomplished, constitutes approval for return to service
      • The only person who can sign the approval for return to service is the holder of the pilot's certificate who is performing the preventive maintenance
        • Therefore, a pilot may not sign off the work of someone else
  • When logging preventative maintenance, be descriptive and specific as this will help referencing them later
  • FAR 43.7 specifies who may log preventative maintenance

Flights Following Preventative Maintenance

Flights Following Preventative Maintenance
  • Following an oil change, pilots must make an appropriate logbook entry, followed by an operational check
  • Start by checking the oil level and for any visible leaks
  • When starting the aircraft, pay closer attention to oil pressure, ensuring it rises in the recommended amount of time
    • If not, shut down the engine
  • Taxiing forward allows the pilot to see if there are any oil spots under the aircraft as a result of initial engine start

Preventative Maintenance Case Studies

Preventative Maintenance Case Studies
  • National Transportation Safety Board Identification: CEN17FA085:
    • The NTSB determines the probable cause(s) of this accident to be: The pilot's negligent maintenance of the airplane, which resulted in improper fuel management, fuel starvation, and a loss of engine power during takeoff due to a missing securing pin in the fuel selector handle, and a subsequent forced landing on unsuitable terrain

Special Flight Permit

Special Flight Permit
  • A special flight permit is a Special Airworthiness Certificate authorizing operation of an aircraft that does not currently meet applicable airworthiness requirements but is safe for a specific flight. Before the permit is issued, an FAA inspector may personally inspect the aircraft or require it to be inspected by an FAA-certificated A&P mechanic or an appropriately certificated repair station to determine its safety for the intended flight. The inspection shall be recorded in the aircraft records
  • The special flight permit is issued to allow the aircraft to be flown to a base where repairs, alterations, or maintenance can be performed; for delivering or exporting the aircraft; or for evacuating an aircraft from an area of impending danger. A special flight permit may be issued to allow the operation of an overweight aircraft for flight beyond its normal range over water or land areas where adequate landing facilities or fuel is not available
  • If a special flight permit is needed, assistance and the necessary forms may be obtained from the local FSDO or Designated Airworthiness Representative (DAR)

Recognizing Impending Failures

Recognizing Impending Failures
  • Time Between Overhaul (TBO) is a means to prevent failures, as covered by Advisory Circular (20-105) Reciprocating Engine Power-Loss Accident Prevention and Trend Monitoring
    • Although TBO is not required to be followed when operating under Part 91, it ensures issues are caught
  • If you starter is no longer turning the prop with the power it once did, consider having the starter replaced
  • Inspect the aircraft for corrosion during preflight to identify its presence, any hazards, and treatment options

Finding A&Ps

Finding A&Ps

Conclusion

Conclusion
  • Sometimes the best preventative maintenance measure is simple use, keeping the fuel tanks full to avoid corrosion, and sheltering the aircraft whenever possible
  • Remember, preventive maintenance is limited to work that does not involve complex assembly, and the list provided by FARs is therefore not all-inclusive
  • Some aircraft designs will prevent some of these preventative items from actually possible
    • For example, if the brakes must be disassembled to perform preventative maintenance on landing gear tires then you've now crossed the line into non-preventative or, standard maintenance
  • There are resources available if you've further questions:
    • A&Ps
    • IAs
    • Repair Stations (Part 145)
    • FSDO
  • Always replace parts with those approved by the maintenance manuals
    • Even if parts look the same (say at NAPA Auto Parts), they're designed to different technical standards!
    • Also, replacing approved parts will ensure there is no significant impact to the weight and balance
  • For any questions regarding the logging of maintenance, reach out to your local mechanic on the field
  • For any questions, contact your local Flight Standards District Office and talk to an airworthiness inspector
  • Always follow the guidelines as published in FAR 43.13, essentially saying, following what the manufacturer says
  • Preventive maintenance is only authorized for part 91 operations, not commercial
  • Consider discussing the nuances between mandatory and recommended maintenance with an aircraft mechanic
  • See also Coleal-Bombardier Legal Interpretation to gain insight on how the FAA views preventative maintenance
  • If able, consider an aircraft dehumidifer, especially when storing, to prevent corrosion
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References

References