54-24-04 MARTIN: Applies to All Models 202 and 202A Aircraft.
Compliance required as indicated.
Several cases of cracks in the main landing gear trunnion fittings (P/N 2021A23307, 2021A23308, 2021A23309, 2021A23310) have been reported. These cracks have been in the area of the boss and the web. To preclude failure of these parts all aircraft must be inspected and reworked as follows:
I. Compliance required as soon as practical but not later than December 10, 1954, unless already accomplished.
Thoroughly clean fittings and inspect using a dye penetrant inspection method. If a crack is found, rework the part in accordance with item II. If no cracks exist the part must be reinspected using an 8- power magnifying glass, dye penetrant method or equivalent every 250 hours plus or minus 75 hours.
II. Compliance required prior to return to service if a crack is found.
The fitting may be repaired by grinding provided the crack does not exceed either 2 inches in length or exceed 0.060 inch in depth. Parts having cracks exceeding either of the above limitations must be replaced. Repaired parts must be etch inspected. Repaired parts must be reinspected using an 8-power magnifying glass, dye penetrant method or equivalent every 250 hours plus or minus 75 hours.
III. New parts of the same design (P/N 2021A23307 through 23310) must be inspected at the first regular inspection period of approximately 1,000 hours after installation, and thereafter at every 250 hours plus or minus 75 hours using an 8-power magnifying glass, dye penetrant method or equivalent.
IV. Replacement parts of the improved design (P/N 2021A23307-1 through 23310-1) must be inspected visually at the first regular inspection period of 1,000 hours after installation, and thereafter at intervals not exceeding 500 hours. At 7,500 hours after installation, and thereafter at every 250 hours plus or minus 75 hours, inspect the fitting using a dye penetrant method orequivalent.
(NOTE: All specified inspection intervals are based on an average landing frequency of one per hour. Where average landing frequency exceeds this, there should be a corresponding decrease in the inspection intervals.)
(Martin telegram of November 3, 1954, to all 202 and 202A operators covers this subject.)