Airframe Inspection can be up to 15 percent of the Airframe test, and much of it comes straight from 14 CFR parts 39, 43 and 91. These are the rules and figures to know.
Annual and 100-hour inspections
- An annual inspection must have been done within the preceding 12 calendar months, so it stays valid through the end of the twelfth calendar month after the month of the inspection. An annual completed March 10 is good through March 31 of the following year (14 CFR 91.409(a)).
- An aircraft used for flight instruction for hire may exceed the 100-hour limit by not more than 10 hours while en route to a place where the inspection can be done, and the excess counts toward the next 100 hours (14 CFR 91.409(b)).
- A 100-hour checklist may be of the person's own design, the manufacturer's, or from another source, but must include the scope and detail of appendix D to part 43 (14 CFR 43.15(c)(1)).
Other time-based checks
- The static pressure system, altimeter and altitude reporting system must have been tested within the preceding 24 calendar months for IFR flight in controlled airspace (14 CFR 91.411(a)(1)).
- An ATC transponder must have been tested and inspected within the preceding 24 calendar months (14 CFR 91.413(a)).
- An ELT must be inspected within 12 calendar months after the last inspection (14 CFR 91.207(d)). Its batteries are replaced or recharged after more than 1 cumulative hour of use, or when 50 percent of their useful life has expired (14 CFR 91.207(c)).
Maintenance record entries
- The signature, certificate number and kind of certificate of the person approving work for return to service constitute approval only for the work performed (14 CFR 43.9(a)(4)).
- An inspection entry gives the type of inspection and a brief description of its extent, the date and aircraft total time in service, and the approving person's signature, certificate number and kind of certificate (14 CFR 43.11(a)(2)).
- A person who finds the aircraft unairworthy must give the owner or lessee a signed and dated list of the discrepancies (14 CFR 43.11(b)).
- Records of total time in service, life-limited part status, inspection status and AD status are retained and transferred with the aircraft when it is sold (14 CFR 91.417(b)(2)).
- A component may be described as overhauled only if it has been disassembled, cleaned, inspected, repaired as necessary, reassembled and tested to approved or acceptable standards and data (14 CFR 43.2(a)).
Airworthiness directives
- ADs are legally enforceable rules, and you violate the regulation each time you operate the aircraft without meeting the AD's requirements (14 CFR 39.7, 39.9).
- If a change in a product affects the ability to accomplish an AD's actions in any way, the owner must request FAA approval of an alternative method of compliance (14 CFR 39.17).
- When an AD incorporates a service document and the two conflict, the AD must be followed (14 CFR 39.27).
- The owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition, including compliance with part 39 (14 CFR 91.403(a)).
Methods and life-limited parts
- A mechanic uses the methods, techniques and practices in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness, or other methods acceptable to the FAA (14 CFR 43.13(a)).
- A life-limited part has a mandatory replacement limit in the type design, the Instructions for Continued Airworthiness or the maintenance manual. A person who removes and later transfers one must transfer the mark, tag or other record used to control its life status, unless the part is mutilated before transfer (14 CFR 43.10).
Inspection techniques and corrosion
- Wrinkled wing skin is the most easily detected sign of an excessive load imposed during a landing. After severe turbulence, a few rivets are removed from wrinkled areas and their shanks examined for shear.
- A suspect aluminum structure exposed to intense heat can be checked with an eddy current conductivity tester; suspect steel is checked with a Rockwell C hardness tester.
- When searching for surface cracks with a flashlight, direct the beam at a 5 to 45 degree angle to the surface, and confirm suspected cracks with a 10-power magnifying glass or another NDI method.
- Only qualified radiographers operate x-ray units for radiographic inspection.
- A conformity check verifies that installed equipment matches the type certificate data sheet.
- Filiform corrosion shows a worm-like trace under a paint film; exfoliation corrosion lifts surface grains and is most often seen on extruded sections; the smoking rivet is the common example of fretting corrosion.
Practice FAA Aviation Mechanic Airframe questions with explanations and timed mock tests.