Airworthiness Directive · Amendment 39-14070 · Boeing Model 747 Series Airplanes
Boeing Model 747 Series Airplanes
Superseded. A later AD replaced this one: AD 2006-22-15. Comply with the one in force.
This AD applies to all Boeing Model 747 series airplanes, certificated in any category.
The FAA is superseding an existing airworthiness directive (AD) that applies to all Boeing Model 747 series airplanes. The existing AD currently requires repetitive inspections for cracking of the top and side panel webs and panel stiffeners of the nose wheel well (NWW), and corrective actions if necessary. This new AD expands the area of inspection, adds a new "secondary" inspection if certain cracking is found, and reduces the intervals for the repetitive inspections. This AD is prompted by a report of an in-flight decompression of a Model 747-100 series airplane that had accumulated 27,241 total flight cycles. We are issuing this AD to detect and correct fatigue cracks in the top and side panel webs and stiffeners of the NWW, which could compromise the structural integrity of the NWW and could lead to the rapid decompression 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.
Prior to the accumulation of 16,000 total flight cycles, or within 1,000 flight cycles after January 27, 2005 (the effective date of AD 2004-25-23), whichever is later, do the inspections specified in either paragraph (f)(1) or (f)(2) of this AD.
(1) Do the inspections specified in paragraphs (f)(1)(i) and (f)(1)(ii) of this AD in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003. Repeat the inspections thereafter at intervals not to exceed 1,000 flight cycles.
(i) Do detailed and ultrasonic inspections of the top and side panel webs of the NWW for cracks.
(ii) Do detailed and surface high frequency eddy current (HFEC) inspections of the top and side panel stiffeners of the NWW for cracks.
(2) Do the inspections specified in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2465, Revision 2, dated November 11, 2004. Repeat the inspections thereafter at the intervals specified in paragraphs (f)(2)(i) and (f)(2)(ii) of this AD.
(i) Do external detailed inspections of the top and side panel webs of the NWW (specified as Area 1 and Area 2 in the service bulletin), as applicable, for cracks. Repeat the inspections thereafter at intervals not to exceed 1,000 flight cycles.
(ii) Do internal detailed and surface HFEC inspections of the top and side panel stiffeners of the NWW (specified as Area 3 in the service bulletin) for cracks. Repeat the inspections thereafter at intervals not to exceed 6,000 flight cycles.
Note 1: For the purposes of this AD, a detailed 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 mirrors, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
Do an external detailed inspection of the top and sidewall panel webs of the NWW (specified as Area 1 and Area 2 in the service bulletin) for cracks, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin (ASB) 747-53A2465, Revision 4, dated February 24, 2005, at the earlier of the times specified in paragraphs (g)(1) and (g)(2) of this AD. Accomplishment of this inspection terminates the requirements for the inspections specified in paragraphs (f)(1)(i) and (f)(2)(i) of this AD.
(1) At the later of the times specified in paragraph (g)(1)(i) and (g)(1)(ii) of this AD:
(i) Before accumulating 20,000 total flight cycles.
(ii) Within 100 flight cycles or 90 days after the effective date of this AD, whichever occurs first.
(2) At the later of the times specified in paragraphs (g)(2)(i) and (g)(2)(ii) of this AD:
(i) Before accumulating 16,000 total flight cycles.
(ii) Within 1,000 flight cycles after the effective date of this AD.
Repeat the inspection required by paragraph (g) of this AD at the intervals specified in paragraph (h)(1) or (h)(2) of this AD, as applicable.
(1) For airplanes with less than 20,000 total flight cycles as of the effective date of this AD, repeat at intervals not to exceed 1,000 flight cycles until the first inspection after the airplane reaches 20,000 total flight cycles.
(2) For airplanes with 20,000 total flight cycles or more, repeat at intervals not to exceed 500 flight cycles.
(i) Do a UT inspection of the sidewall panel web for cracks, in accordance with Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005, at the later of the times specified in paragraphs (i)(1) and (i)(2) of this AD. Repeat the inspections thereafter at intervals not to exceed 500 flight cycles.
(1) Prior to the accumulation of 20,000 total flight cycles.
(2) Within 100 flight cycles or within 90 days after the effective date of this AD, whichever occurs first.
Except as specified in paragraph (l) of this AD, if any crack is found during any inspection required by this AD, prior to further flight, do any applicable additional detailed inspections of stiffeners and beams and make repairs, in accordance with the Accomplishment Instructions of Boeing ASB 747-53A2465, Revision 4, dated February 24, 2005.
Inspections and corrective actions accomplished before January 27, 2005, in accordance with Boeing ASB 747-53A2465, dated April 5, 2001, are considered acceptable for compliance with the corresponding inspections specified in paragraph (f) of this AD. Inspections and corrective actions accomplished before the effective date of this AD, in accordance with Boeing Service Bulletin 747-53A2465, Revision 1, dated October 16, 2003; Revision 2, dated November 11, 2004; and Revision 3, dated December 23, 2004; are considered acceptable for compliance with the corresponding inspections specified in paragraphs (g) and (h) of this AD.
Where the ASB specifies contacting the manufacturer if certain cracking is found, this AD requires repairing the cracking according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, or by an Authorized Representative for the Boeing Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. The repair must be accomplished before further flight. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the Manager's approval letter must specifically refer to this AD.
Although the Boeing ASB specifies that operators should report inspection results to the manufacturer, this AD does not require those inspection results to be reported.
