Airworthiness Directive · Amendment 39-11794 · Boeing Model 747 Series Airplanes
Boeing Model 747 Series Airplanes
Model 747 series airplanes; as listed in Groups 1, 2, and 5 of Boeing Alert Service Bulletin 747-54A2184, Revision 1, dated May 6, 1999; 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)(1) 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 747 series airplanes, that currently requires repetitive inspections to detect fatigue cracking or loose or missing fasteners of the aft torque bulkheads of the outboard nacelle struts; and repair, if necessary. This amendment expands the applicability of the existing AD to include certain additional airplanes, and removes certain other airplanes from the applicability of the existing AD. For all airplanes subject to this AD, this amendment also requires accomplishment of a new terminating action. This action is necessary to prevent fatigue cracking and loose or missing fasteners in the aft torque bulkheads of the outboard nacelle struts, which could result in failure of an outboard nacelle strut diagonal brace load path and possible separation of the nacelle from the wing. This action is intended to address the identified unsafe condition.
To prevent fatigue cracking and loose or missing fasteners in the aft torque bulkheads of the outboard nacelle struts, which could result in failure of an outboard nacelle strut diagonal brace load path and possible separation of the nacelle from the wing, accomplish the following:
(a) For airplanes identified as Groups 1 and 2 airplanes in Boeing Alert Service Bulletin 747-54A2184, dated July 3, 1997: Prior to the accumulation of 8,000 total flight cycles, or within 8,000 flight cycles since modification in accordance with AD 95-13-05, amendment 39-9285, or within 30 days after March 18, 1999 (the effective date of AD 99-05-06, amendment 39-11054), whichever occurs latest, perform a detailed visual inspection of the aft torque bulkheads of the number 1 and number 4 nacelle struts to detect fatigue cracking and loose or missing fasteners. The inspection shall be accomplished in accordance with Part I of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2184, dated July 3, 1997, or Revision 1, dated May 6, 1999.
Note 2: There is a typographical error on Sheet 3 of Figure 1 of Boeing Alert Service Bulletin 747-54A2184, dated July 3, 1997. The words “Group 1 airplanes” should read “Groups 1 and 2 airplanes.”
(1) If no cracking, and no loose or missing fastener, is found, repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin.
(2) If any cracking, or any loose or missing fastener, is found, prior to further flight, repair in accordance with Part III of the alert service bulletin. Repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin. Where the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, 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. 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.
(b) For airplanes identified as Groups 1 and 2 airplanes in Boeing Alert Service Bulletin 747-54A2184, dated July 3, 1997: Prior to the accumulation of 8,000 total flight cycles, or within 8,000 flight cycles since modification in accordance with AD 95-13-05, amendment 39-9285, or within 30 days after March 18, 1999, whichever occurs latest, perform a non-destructive test (NDT) inspection of the aft torque bulkheads of the number 1 and number 4 nacelle struts to detect fatigue cracking. The NDT inspection shall be accomplished in accordance with Part II of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2184, dated July 3, 1997, or Revision 1, dated May 6, 1999.
Note 3: The alert service bulletin refers to a variety of NDT inspections, consisting of ultrasonic inspections, surface eddy current inspections, and open-hole eddy current inspections. The logic diagram in Figure 1 of the alert service bulletin states the conditions under which each of these inspections is to be performed.
(1) If no cracking is found, repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin.
(2) If any cracking is found, prior to further flight, repair in accordance with Part III of the alert service bulletin. Repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin. Where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, 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. 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.
Note 4: 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.”
(c) For airplanes identified as Group 5 of Boeing Alert Service Bulletin 747-54A2184, Revision 1, dated May 6, 1999: Prior to the accumulation of 8,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, perform a detailed visual inspection of the aft torque bulkheads of the number 1 and number 4 nacelle struts to detect fatigue cracking and loose or missing fasteners. The inspection shall be accomplished in accordance with Part I of the Accomplishment Instructions of the alert service bulletin.
(1) If no cracking, and no loose or missing fastener, is found, repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin.
(2) If any cracking, or any loose or missing fastener, is found, prior to further flight, repair in accordance with Part III of the alert service bulletin. Repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin. Where the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, repair in accordance with a method approved by the Manager, Seattle ACO, FAA, Transport Airplane Directorate; 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. 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 airplanes identified as Group 5 airplanes in Boeing Alert Service Bulletin 747-54A2184, Revision 1, dated May 6, 1999: Prior to the accumulation of 8,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, perform an NDT inspection of the aft torque bulkheads of the number 1 and number 4 nacelle struts to detect fatigue cracking. The NDT inspection shall be accomplished in accordance with Part II of the Accomplishment Instructions of the alert service bulletin.
Note 5: The alert service bulletin refers to a variety of NDT inspections, consisting of ultrasonic inspections, surface eddy current inspections, and open-hole eddy current inspections. The logic diagram in Figure 1 of the alert service bulletin states the conditions under which each of these inspections is to be performed.
(1) If no cracking is found, repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin.
(2) If any cracking is found, prior to further flight, repair in accordance with Part III of the alert service bulletin. Repeat the inspection thereafter at the intervals specified in Figure 1 of the alert service bulletin. Where the alert service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, 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. 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.
(e) For airplanes identified as Group 1, 2, and 5 airplanes in Boeing Alert Service Bulletin 747-54A2184, Revision 1, dated May 6, 1999: At the time specified in paragraph (e)(1), (e)(2), or (e)(3), as applicable, accomplish the terminating action (installation of doublers and fillers on the forward side of the lower spar fitting) in accordance with the alert service bulletin. Accomplishment of this paragraph constitutes terminating action for the repetitive inspections required by this AD.
Note 6: There is an error in Item 3.A.5.c. under “Part 4—Terminating Action” in the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2184, Revision 1. The words, “as shown by Figure 11,” should read “as shown by Figure 12.”
(1) For airplanes in Groups 1, 2, and 5 on which the interim repair described in Part 3 of the Accomplishment Instructions of the alert service bulletin has NOT been accomplished; and Groups 1 and 2 airplanes on which the requirements of AD 95-13-05, amendment 39-9285, have NOT been accomplished: Accomplish the terminating action prior to the accumulation of 8,000 total flight cycles or within 5 years after the effective date of this AD, whichever occurs later.
(2) For airplanes in Groups 1, 2, and 5 on which the interim repair described in Part 3 of the Accomplishment Instructions of the alert service bulletin HAS been accomplished: Accomplish the terminating action within 3,000 flight cycles after accomplishment of the interim repair, or within 18 months after the effective date of this AD, whichever occurs later.
(3) For airplanes in Groups 1 and 2 on which the requirements of AD 95-13-05, amendment 39-9285, HAVE been accomplished: Accomplish the terminating action within 8,000 flight cycles after accomplishment of the requirements of AD 95-13-05, amendment 39-9285, or within 5 years after the effective date of this AD, whichever occurs later.
(f)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.
(2) Alternative methods of compliance, approved previously in accordance with AD 99-05-06, amendment 39-11054, are approved as alternative methods of compliance with this AD.
Note 7: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
