Airworthiness Directive · Amendment 39-11777 · Boeing Model 747-400 and 767-200 and -300 Series Airplanes Powered by Pratt & Whitney Model PW4000 Series Engines
Boeing Model 747-400 and 767-200 and -300 Series Airplanes Powered by Pratt & Whitney Model PW4000 Series Engines
Model 747-400 series airplanes powered by Pratt & Whitney PW4000 series engines, line numbers 696 through 1100 inclusive; and Model 767-200 and -300 series airplanes powered by Pratt & Whitney PW4000 series engines, line numbers 1 through 646 inclusive; 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 (d) 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 adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-400 and 767-200 and -300 series airplanes, that requires repetitive inspections to detect damage and wear of the auxiliary track assembly of the thrust reverser, and corrective actions, if necessary. This amendment also requires eventual repair of the auxiliary track assembly, or replacement of the slider and liner or the entire assembly, with new, improved parts, which, when accomplished, would terminate the repetitive inspections. This amendment is prompted by reports of damage and wear to the auxiliary track assembly. The actions specified by this AD are intended to prevent a slider disengaging from the auxiliary track assembly, which could lead to separation of a portion of the thrust reverser from the airplane during flight, possible impact of separated portions on airplane structure, and consequent possible rapid decompression of the airplane, reduced controllability of the airplane, or reduced structural integrity of the fuselage.
To prevent a slider disengaging from the auxiliary track assembly, which could lead to separation of a portion of the thrust reverser from the airplane during flight, possible impact of separated portions on airplane structure, and consequent possible rapid decompression of the airplane, reduced controllability of the airplane, or reduced structural integrity of the fuselage, accomplish the following:
(a) Prior to the accumulation of 3,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, perform a detailed visual inspection of the upper and lower auxiliary track assemblies on each thrust reverser half of each engine to detect missing segments of the track lip; to detect signs that the slider has disengaged from the track; to detect cracks, gouges, and wear of the liner; and measure the auxiliary track beam dimensions; in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable.
Note 2: For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
(1) If no discrepancy is detected, repeat the detailed visual inspection thereafter at intervals not to exceed 3,000 flight cycles or 7,000 flight hours, whichever occurs earlier, until paragraph (b) or (c), as applicable, has been accomplished.
(2) If the auxiliary track lip has a missing segment of 3 inches or longer, or longitudinal cracks at the base of the lip, or other indications that the slider has disengaged from the track in the forward 4 inches, prior to further flight, repair in accordance with Part A of the Accomplishment Instructions of the applicable service bulletin. Repeat the detailed visual inspection thereafter at the applicable intervals specified in Part A of the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
(3) If the auxiliary track lip has a missing segment of 3 inches or longer, or longitudinal cracks at the base of the lip, or other indications that the slider has disengaged from the track AFT of the forward four inches, accomplish paragraphs (a)(3)(i) or (a)(3)(ii) of this AD.
(i) Prior to further flight, repair in accordance with Part B of the Accomplishment Instructions of the applicable service bulletin. Repeat the detailed visual inspection thereafter at the applicable intervals specified in Part B of the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
(ii) Accomplish both paragraphs (a)(3)(ii)(A) and (a)(3)(ii)(B) of this AD:
(A) Prior to further flight, deactivate the associated thrust reverser in accordance with Section 78-2 of Boeing Document D6U10151, “Boeing 747-400 Dispatch Deviations Guide,” Revision 11, dated March 31, 1998 (for Model 747-400 series airplanes); or Section 78-2 of Boeing Document D630T002, “Boeing 767 Dispatch Deviations Guide,” Revision 19, dated May 14, 1999 (for Model 767 series airplanes); as applicable. No more than one thrust reverser on any airplane may be deactivated under the provisions of the paragraph.
Note 3: The airplane may be operated for up to 30 days in accordance with the provisions and limitations specified in the operator's FAA-approved Master Minimum Equipment List, provided that no more than one thrust reverser on the airplane is inoperative.
(B) Within 30 days after deactivation of any thrust reverser in accordance with paragraph (a)(3)(ii)(A) of this AD, the thrust reverser must be repaired in accordance with the Accomplishment Instructions of the applicable service bulletin; once this is accomplished, the thrust reverser may then be reactivated. Repeat the detailed visual inspection thereafter at the applicable intervals specified in the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
(b) For any auxiliary track assembly on which no discrepancy is detected during any detailed visual inspection required by paragraph (a) of this AD: Replace the liner and slider of the auxiliary track assembly with a new, improved liner and slider, in accordance with Part A of the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable; at the later of the times specified in paragraphs (b)(1) and (b)(2) of this AD. Such action constitutes terminating action for the requirements of this AD for that assembly.
(1) Within 6,000 flight cycles, 14,000 flight hours, or 5 years after the date of the first inspection, whichever occurs earliest; or
(2) Within 4 years after the effective date of this AD.
(c) For any auxiliary track assembly on which any discrepancy is detected during any detailed visual inspection required by paragraph (a) of this AD: Repair the auxiliary track assembly (replace the slider and liner and install a retainer bar), or replace with a new, improved assembly (including a new liner and slider), as applicable, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable; at the later of the times specified in paragraphs (c)(1) and (c)(2) of this AD. Such action constitutes terminating action for the requirements of this AD for that assembly.
(1) Within 4,500 flight cycles, 10,000 flight hours, or 3 years after the date of the first repair, whichever occurs earliest; or
(2) Within 2 years after the effective date of this AD.
Note 4: Inspections and repairs accomplished prior to the effective date of this AD in accordance with Boeing Service Bulletin 747-78A2164, Revision 1, or Boeing Service Bulletin 767-78A0079, Revision 1, both dated February 5, 1998; are considered acceptable for compliance with the applicable actions specified in this AD.
