AD 80-02-11

80-02-11 DeHAVILLAND: Amendment 39-3672. Applies to DHC-7 airplanes, S/N 1 through 13 inclusive, certificated in all categories.

Compliance required as indicated, unless already accomplished.

To prevent possible landing gear support structure failure due to looseness of the main landing gear frame attachment bolts, accomplish the following:

1. Within the next 25 hours in service after the effective date of this AD, unless previously accomplished within the last 295 hours in service, inspect the main landing gear frame bolts, P/N MS21250H10042, for evidence of improper torque.

2. If evidence of improper torque is found at any bolt location,

a. cut an access hole at all four bolt locations as detailed in DeHavilland Service Bulletin No. 7-54-4, ACCOMPLISHMENT INSTRUCTIONS, Page 2, paragraphs 1 and 2. Retorque all bolts to 1400-1650 inch-pounds and cover the access holes with snap hole plug P/N CSP80-20 or equivalent. Mark the end of the bolt, nut and adjacent structure with a red line. Visually inspect the red marking at each location for signs of movement at intervals not to exceed 320 hours in service from last inspection until the modification in paragraph 2.b. is accomplished, or

b. incorporate DeHavilland modification (Ref. S/B 7-54-4).

3. For bolts that are found to be properly torqued, mark and inspect bolts as above in paragraph 2.a. until the modification is accomplished.

4. Incorporate DeHavilland modification in accordance with S/B No. 7-54-4, ACCOMPLISHMENT INSTRUCTIONS, or equivalent, within 1900 hours in service from the initial inspection in paragraph 1.

5. Equivalent parts and modification must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

This amendment is effective January 24, 1980.