Airworthiness Directive · Amendment 39-15486 · Boeing Model 747 Airplanes
Boeing Model 747 Airplanes
This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-32A2482, dated June 14, 2007.
We are adopting a new airworthiness directive (AD) for certain Boeing Model 747 airplanes. This AD requires inspecting the trunnion fork assembly of the wing landing gears to determine the part number and serial number and to determine the category of the trunnion fork assemblies. For certain airplanes, this AD also requires, if necessary, various inspections to detect discrepancies of the trunnion fork assemblies, related investigative/corrective actions, and a terminating action. This AD results from a report of a fractured trunnion fork assembly. We are issuing this AD to prevent a fractured trunnion fork assembly, which could result in the collapse of a wing landing gear on the ground and possible damage to hydraulic equipment and the aileron and spoiler cables. Such damage could result in reduced controllability of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
The term “service bulletin,” as used in this AD, means Boeing Alert Service Bulletin 747-32A2482, dated June 14, 2007.
Within 18 months after the effective date of this AD, inspect the pad-up area on the forward upper inboard surface of the trunnion fork assembly of both the left and right wing landing gears to determine the part number and serial number and to determine the category of the trunnion fork assemblies. A review of airplane maintenance or delivery records is acceptable instead of the inspection if the part number and serial number of the installed fork assembly can be conclusively determined from that review. Do the actions in accordance with the Accomplishment Instructions of the service bulletin.
If any part number and serial number identified as Category A, B, C, or D in Tables 2 and 3 of paragraph 1.E., “Compliance,” of the service bulletin is found installed during the inspection required by paragraph (g) of this AD: At the applicable compliance time(s) listed in Table 4 or 5 of paragraph 1.E., “Compliance,” of the service bulletin, except as provided by paragraph (i) of this AD, do the applicable action(s) in Table 1 of this AD and applicable related investigative/corrective actions, in accordance with the Accomplishment Instructions of the service bulletin.
| For— | Do— | And— | Or— |
|---|---|---|---|
| (1) Categories A and C trunnion fork assemblies | A detailed inspection for damage to the protective finish and for corrosion of the trunnion fork assembly and a high frequency eddy current (HFEC) inspection to detect cracks (Part 2) | An ultrasonic inspection to determine the wall thickness in the area forward of the outer cylinder attach lugs in 8 zones, and a hardness measurement if applicable (Part 3) | Do the terminating action (Part 5). |
| (2) Categories B and D trunnion fork assemblies | An ultrasonic inspection to determine the wall thickness in the area forward of the outer cylinder attach lugs in 8 zones, and a hardness measurement (Part 3) | None | None. |
(i) Where paragraph 1.E., “Compliance,” of the service bulletin specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.
Replacing the trunnion fork assembly of the wing landing gear with a trunnion fork assembly identified in Part 5 of the Accomplishment Instructions of the service bulletin, in accordance with and at the applicable time specified in Table 4 or 5 of paragraph 1.E., “Compliance,” of the service bulletin, constitutes terminating action for the requirements of this AD for that side only.
