67-19-04 MARTIN: Amdt. 39-432, Part 39, Federal Register June 15, 1967. Applies to Type 202, 202A and 404 Airplanes Incorporating Engine Mount, P/N's A10100, A10100-9, 2021C11039-9, A16647-81, 404-5000004, 404-5000004-59, 404-5000005, or 404-5000005-29.
Compliance required as indicated.
To detect cracks and corrosion in the engine mounts, accomplish the following:
(a) Within the next 100 hours' time in service after the effective date of this AD, unless already accomplished within the last 100 hours' time in service, and thereafter at intervals not to exceed 200 hours' time in service from the last inspection; visually inspect the engine mount tubular members and welds for cracks, using a glass of at least 10-power, or use an FAA- approved equivalent inspection. If a crack is found comply with (c) before further flight.
(b) Within the next 250 hours' time in service after the effective date of this AD, unless already accomplished within the last 750 hours' time in service, and thereafter at intervals not to exceed 1000 hours' time in service from the last inspection, or one (1) year whichever occurs first, inspect the engine mount tubular members and welds for external and internal cracks and corrosion, using both Magnaflux and X-ray or FAA-approved equivalent inspections. Remove paint and sandblast the engine mount prior to inspecting, or use an FAA-approved equivalent method. The sandblasting operation should be limited to the removal of any light rust or other superficial discolorations as necessary to give a clean surface to conduct Magnaflux inspection. If a crack is found comply with (c) before further flight. Engine mounts inspected within the last 750 hours' time in service using Magnaflux and X-ray, or FAA-approved equivalent inspections, but without sandblasting need not be reinspected before 1000 hours' of time in service from such inspection.
(c) If a crack is found in the weld metal or in any tube between welds, and the crack is parallel to the tube axis, repair or replace the cracked part in accordance with the procedures outlined in the latest FAA-approved revision of the applicable Martin structural repair manual, or with an FAA-approved equivalent repair, or replace the cracked part with a part of the same part number that has been inspected in accordance with (b) and found free of cracks and corrosion, or with an FAA-approved equivalent part. If a crack is found in any tube wall, and the crack is transverse to the tube axis, replace the entire engine mount with a part of the same part number that has been inspected in accordance with (b) and found free of cracks and corrosion, or with an FAA-approved equivalent part. If a crack is found which is not identified above, approval for continued use of the engine mount must be obtained from the Chief, Engineering and Manufacturing Branch, FAA Eastern Region. Substantiating data must be submitted along with the request.
(d) The repetitive inspection interval specified in paragraph (a) may be increased to 350 hours' time in service, and the repetitive inspection interval specified in paragraph (b) may be increased to 2500 hours' time in service or two (2) years, whichever occurs first, on aircraft whose engine mounts are treated internally at the next required inspection with hot linseed oil. The liquid shall be applied through holes drilled therein, or by immersing the part in a bath of the liquid, or FAA-approved equivalent method. All excess holes must be closed with cadmium- plated or zinc-plated self-tapping screws.
(e) Equivalent inspections and repairs may be approved by an FAA maintenance inspector. Equivalent parts, Structural Repair Manual revisions, and internal treatment methods specified in paragraph (d), must be approved by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
(f) Upon request with substantiating data submitted through an FAA Maintenance Inspector, the compliance timesspecified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region.
This supersedes AD 66-12-01.
This amendment effective June 20, 1967.