AD 2000-11-11

To prevent fatigue cracking of the aft wheel well bulkhead, which could result in rapid in-flight decompression of the airplane, accomplish the following:

(a) For Group 1 airplanes, as identified in Boeing Service Bulletin 777-53A0015, Revision 1, dated March 2, 2000: Prior to the accumulation of 11,000 total flight cycles, or within 4,000 flight cycles after the effective date of this AD, whichever occurs later, perform a one-time general visual inspection to detect excess sealant covering the outer flange of the side fitting and lower chord and splice of the aft wheel well bulkhead, in accordance with Part I of the Accomplishment Instructions of the service bulletin.

Note 2: For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Note 3: Inspections and modifications accomplished prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 777-53A0015, dated June 17, 1999, are considered acceptable for compliance with paragraphs (a), (b), and (d) of this AD.

(1) If no excess sealant is detected, no further action is required by this paragraph.

(2) If any excess sealant is detected, prior to further flight, remove the excess sealant from the aft wheel well bulkhead area in accordance with the service bulletin.

(b) For Groups 1 and 2 airplanes, as identified in Boeing Service Bulletin 777-53A0015, Revision 1, dated March 2, 2000: Prior to the accumulation of 11,000 total flight cycles, or within 4,000 flight cycles after the effective date of this AD, whichever occurs later, perform a one-time general visual inspection to detect cracking of the adjacent structure of the aft wheel well bulkhead and perform a one-time high frequency eddy current (HFEC) inspection to detect cracking of the fastener holes in the web, side fitting, and outer chord of the aft wheel well bulkhead, in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(1) If no cracking is detected during the general visual and HFEC inspections, prior to further flight, modify the aft wheel well bulkhead (including cold working; replacing the fairing support bracket and splice plates with revised fairing support brackets and splice plates; and installing new web doublers and, if necessary, shims), in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(2) If any cracking is detected during the general visual inspection, prior to further flight, accomplish the requirements of paragraph (c) of this AD.

(3) If any cracking is detected during the one-time HFEC inspection, prior to further flight, remove additional fasteners, and perform a second HFEC inspection to detect cracking of the fastener holes, in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(i) If no cracking is detected during the second HFEC inspection, prior to further flight, oversize all the holes to the diameter specified in the service bulletin, and perform a third HFEC inspection to detect cracking of the fastener holes, in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(A) If no cracking is detected during the third HFEC inspection, prior to further flight, replace the fasteners with new fasteners and modify the aft wheel well bulkhead (including cold working; replacing the fairing support bracket and splice plates with revised fairing support brackets and splice plates; and installing new web doublers and, if necessary, shims), in accordance with Part II of the Accomplishment Instructions of the service bulletin.

(B) If any cracking is detected during the third HFEC inspection, prior to further flight, accomplish the requirements of paragraph (c) of this AD.

(ii) If any cracking is detected during the second HFEC inspection, prior to further flight, accomplish the requirements of paragraph (c) of this AD.

(c) For airplanes on which cracking has been detected during any inspection required by paragraph (b)(2), (b)(3)(i)(B), or (b)(3)(ii) of this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Airplane Certification Office (ACO), FAA, Transport Airplane Directorate; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically reference this AD.

(d) For Group 1 airplanes, as identified in Boeing Service Bulletin 777-53A0015, Revision 1, dated March 2, 2000, on which excess sealant was detected and removed in accordance with paragraph (a) of this AD: Prior to further flight following the accomplishment of the modification required by paragraph (b) of this AD, remove any excess sealant in the remaining area of the lower lobe of the aft wheel well bulkhead between stringers S-27L and S-27R, in accordance with the service bulletin.