Airworthiness Directive · Amendment 39-14061 · Boeing Model 747-200B, -200C, -200F, and -400F Series Airplanes
Boeing Model 747-200B, -200C, -200F, and -400F Series Airplanes
This AD applies to Boeing Model 747-200B, -200C, -200F, and -400F series airplanes, line numbers 604 and subsequent, certificated in any category; as listed in Boeing Alert Service Bulletin 747-53A2504, dated August 19, 2004.
The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747 series airplanes. This AD requires repetitive detailed inspections for cracks in the crease beam and adjacent structure of the fuselage, and related investigative and corrective actions if necessary. This AD is prompted by fatigue cracks found in the crease beam during a follow-on inspection of a previously installed modification. We are issuing this AD to find and fix fatigue cracking of the fuselage frame, which could result in reduced structural integrity of the frame and consequent 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.
Accomplish a detailed inspection for cracks in the crease beam and adjacent structure of the fuselage by doing all the applicable actions in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2504, dated August 19, 2004; at the applicable time specified in paragraph (f)(1) or (f)(2) of this AD. Repeat the inspection thereafter at intervals not to exceed 6,000 flight cycles.
(1) For Groups 1 and 2 airplanes as identified in the service bulletin: Before the accumulation of 10,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever is later.
(2) For Groups 3 and 4 airplanes as identified in the service bulletin: Before the accumulation of 14,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever is later.
If any crack is found during any inspection required by paragraph (f) of this AD: Before further flight, repair the cracking in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2504, dated August 19, 2004. If cracking of the crease beam or outer tee chord attachment is found: Before further flight, do a high frequency eddy current inspection for additional cracking, and repair any cracking found, in accordance with the service bulletin. Where the service bulletin specifies contacting the manufacturer for disposition of certain repair conditions, repair before further flight in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or by an Authorized Representative for the Boeing Delegation Option Authorization (DOA) Organization, who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.
For certain airplanes, the service bulletin referenced in this AD recommends reporting any discrepancies to the manufacturer, but this AD does not include that requirement.
