Airworthiness Directive · Amendment 39-11659 · Boeing Model 767 Series Airplanes
Boeing Model 767 Series Airplanes
Model 767 series airplanes; as listed in Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires repetitive inspections to detect cracking or damage of the forward and aft lugs of the diagonal brace of the nacelle strut, and follow-on actions, if necessary. That AD also provides optional terminating action for the repetitive inspections. This amendment requires accomplishment of the previously optional terminating action. This amendment is prompted by a report that a fractured diagonal brace lug was found during a routine maintenance inspection. The actions specified by this AD are intended to prevent cracking of the diagonal brace of the nacelle strut, which could result in failure of the diagonal brace, and consequent fatigue failure of a strut secondary load path and separation of the engine and strut.
To prevent cracking of the diagonal brace of the nacelle strut, which could result in failure of the diagonal brace, and consequent fatigue failure of a strut secondary load path and separation of the engine and strut, accomplish the following:
(a) Perform a detailed visual inspection to detect cracking or damage of the forward and aft lugs of the diagonal brace of the nacelle strut, on the left and right sides of the airplane, in accordance with Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998. Perform the inspection at the time specified in paragraph (a)(1) or (a)(2) of this AD, as applicable.
Note 2: The word “damage” as referenced in this AD, is defined as fretting and/or bushing motion.
(1) For airplanes in Groups 1, 3, and 4: Inspect prior to the accumulation of 12,000 total flight cycles, or within 90 days after April 12, 1999 (the effective date of AD 99-07-06, amendment 39-11091), whichever occurs later.
(2) For airplanes in Group 2: Inspect prior to the accumulation of 24,000 total flight cycles, or within 90 days after April 12, 1999, whichever occurs later.
(b) If no cracking or damage is detected during the inspection required by paragraph (a) of this AD, repeat the inspection thereafter at the interval specified in paragraph (b)(1) or (b)(2) of this AD, as applicable, in accordance with Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998. Repeat the inspection until the actions specified by paragraph (d) or (e) of this AD have been accomplished.
(1) For airplanes in Groups 1, 3, and 4; and for airplanes in Group 2 on which the diagonal brace has accumulated more than 32,000 total flight cycles: Repeat the inspection at intervals not to exceed 1,000 flight cycles.
(2) For airplanes in Group 2 on which the diagonal brace has accumulated 32,000 or fewer total flight cycles: Repeat the inspection at intervals not to exceed 3,000 flight cycles.
(c) If any cracking or damage is detected during any inspection required by paragraph (a) or (b) of this AD: Prior to further flight, remove the diagonal brace and perform additional inspections to detect damage of the strut secondary load paths, in accordance with Part 4 of Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998; and accomplish the requirements of paragraph (c)(1) or (c)(2) of this AD; as applicable.
(1) If any cracking is detected: Prior to further flight, accomplish the requirements of paragraph (c)(1)(i), (c)(1)(ii), or (c)(1)(iii) of this AD, as applicable.
(i) If one lug on one or both ends of the diagonal brace is fractured (Figure 7 of the alert service bulletin), or if two lugs on either end of the diagonal brace are fractured (Figure 8 of the alert service bulletin), prior to further flight: Rework the forward and aft lugs of the diagonal brace in accordance with the rework limits specified in Part 2 of the Accomplishment Instructions of the alert service bulletin.
(ii) Replace the one-piece diagonal brace with a new three-piece diagonal brace, in accordance with Part 3 of the Accomplishment Instructions of the alert service bulletin. Such replacement constitutes terminating action for the requirements of this AD.
(iii) If any additional damage of the alternate load paths is detected, repair in accordance with a method approved by the Manager, Seattle Aircraft 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 (DER) who has been authorized by the Manager, Seattle ACO, to make such findings.
(2) If any damage is detected: Prior to further flight, repair in accordance with a method approved by the Manager, Seattle ACO; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings.
(d) For airplanes on which no cracking is detected during the inspection required by paragraph (a) of this AD, in lieu of accomplishing repetitive inspections in accordance with paragraph (b) of this AD, rework of the forward and aft lugs of the diagonal brace may be accomplished in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998. If such rework is accomplished: Within 12,000 flight cycles after the rework, repeat the inspection required by paragraph (a) of this AD; and, prior to the accumulation of 37,500 total flight cycles on the diagonal brace, replace the one-piece diagonal brace with a new three-piece diagonal brace, in accordance with Part 3 of the Accomplishment Instructions of the alert service bulletin. Such replacement constitutes terminating action for the requirements of this AD.
(e) Prior to the accumulation of 37,500 total flight cycles, or within 180 days after the effective date of this AD, whichever occurs later: Replace the one-piece diagonal brace with a new three-piece diagonal brace, in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 767-54A0094, dated May 22, 1998. Such replacement constitutes terminating action for the requirements of this AD.
