Airworthiness Directive · Amendment 39-15822 · Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes
Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes
This AD applies to Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008.
The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747-100, 747-100B, 747- 200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. That AD currently requires an inspection to determine if acceptable external skin doublers are installed at the stringer 6 (S-6) lap splices, between station (STA) 340 and STA 400. For airplanes without the acceptable external skin doublers, the existing AD also requires repetitive related investigative actions and corrective actions if necessary. The existing AD also provides an optional terminating modification for the repetitive related investigative actions. This new AD mandates the optional terminating modification. This AD results from a report of cracked fastener holes at the right S-6 lap splice between STA 340 and STA 380. We are issuing this AD to prevent cracking in the fuselage skin, which could result in rapid decompression and loss of structural integrity 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.
The term “alert service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008.
For airplanes identified as Group 1, Configuration 2, in Boeing Alert Service Bulletin 747-53A2748, dated May 9, 2008: At the latest of the times specified in paragraphs (g)(1), (g)(2), and (g)(3) of this AD, do an external general visual inspection to determine if acceptable external skin doublers are installed at the left- and right-side S-6 lap splices, in accordance with Part 1 of the alert service bulletin.
(1) Prior to the accumulation of 10,000 total flight cycles.
(2) Within 8,000 flight cycles after a modification was done in accordance with Boeing Service Bulletin 747-53-2253.
(3) Within 15 days or 100 flight cycles after May 20, 2008 (the effective date of AD 2008-10-15), whichever occurs first.
If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers in accordance with the alert service bulletin are found installed at both the left- and right-side S-6 lap splices, no further work is required by this AD.
(i) If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers in accordance with alert service bulletin are not found installed at either the left- or right-side S-6 lap splice: Before further flight, do all applicable related investigative and corrective actions by doing all actions specified in Part 2 of the alert service bulletin. Repeat the applicable related investigative actions thereafter at intervals not to exceed 300 flight cycles until the modification specified in paragraph (j) of this AD is done.
If, during the inspection required by paragraph (g) of this AD, acceptable external skin doublers as specified in the alert service bulletin are not found installed at either the left- or right-side S-6 lap splice: Within 3,000 flight cycles after doing the initial related investigative actions in paragraph (i) of this AD, or within 300 flight cycles after the effective date of this AD, whichever occurs later, install acceptable external skin doublers at both the left- and right-side S-6 lap splices, as applicable. The installation of the acceptable skin doublers is required on the side of the airplane that does not have the acceptable doublers already. The installation includes doing an open-hole high-frequency eddy current (HFEC) inspection of the skin for cracking, and trimming out cracking as applicable. Do all actions in accordance with the alert service bulletin. Doing this installation terminates the repetitive related investigative actions required by paragraph (i) of this AD.
Note 1: The alert service bulletin refers to Boeing Service Bulletins 747-53-2253, Revision 3, dated March 24, 1994; and 747-53-2272, Revision 18, dated May 16, 2002; as additional sources of service information for accomplishment of the modification (installation of acceptable external skin doublers).
Note 2: AD 90-06-06, amendment 39-6490, requires, among other actions, a modification as specified in Boeing Service Bulletin 747-53-2253, dated December 14, 1984.
Note 3: AD 90-23-14, amendment 39-6801, requires inspections as specified in Boeing Service Bulletin 747-53-2253, Revision 2, dated March 29, 1990.
