Airworthiness Directive · Amendment 39-14571 · Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes
Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP Series Airplanes
This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes, certificated in any category; equipped with Pratt & Whitney JT9D-3 and -7 series engines, except JT9D-70 engines; as identified in Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005.
The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 747SP series airplanes. That AD currently requires repetitive detailed and ultrasonic inspections of the thrust links of the rear engine mounts for any crack or fracture and corrective actions if necessary. This new AD requires repetitive replacement of the thrust links with new or overhauled thrust links, which ends the repetitive detailed and ultrasonic inspections. This AD results from the finding of fractured and cracked forward lugs of the rear engine mount thrust link on the number one strut on two airplanes. We are issuing this AD to prevent cracked or fractured thrust links that could lead to the loss of the load path for the rear engine mount bulkhead and damage to other primary engine mount structure, which could result in the in-flight separation of the engine from the airplane and consequent loss of control 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 “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 747-71A2309, dated August 18, 2005.
Within 90 days after September 30, 2005 (the effective date of AD 2005-19-06), do a detailed inspection and ultrasonic inspection of thrust link lugs having part number (P/N) 65B90360-1 or -4 of the rear engine mount of struts 1, 2, 3, and 4 for any crack or fracture, in accordance with Part 1 of the service bulletin. If the thrust link is not found cracked or fractured: Repeat the inspections thereafter at intervals not to exceed 1,200 flight cycles or 18 months, whichever is first, until the repetitive replacement or overhaul of the thrust link required by paragraph (k) of this AD is accomplished. Accomplishing the repetitive replacement or overhaul of a thrust link as specified in paragraph (h) or (k) of this AD terminates the repetitive inspections for that thrust link only.
If a cracked thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraph (h)(1) of this AD. If a fractured thrust link is found during any inspection required by paragraph (g) of this AD or during any replacement or overhaul done in accordance with the service bulletin: Before further flight, do the actions specified in paragraphs (h)(1) and (h)(2) of this AD.
(1) Replace the thrust link with a new or overhauled thrust link in accordance with Part 2 of the service bulletin; except as provided by paragraph (i) of this AD. Repeat the replacement at the applicable compliance time specified in paragraph (h)(1)(i) or (h)(1)(ii) of this AD.
(i) For replacement with a thrust link assembly having P/N 65B90360-1 or -4: Thereafter at intervals not to exceed 6,000 flight cycles.
(ii) For replacement with a thrust link assembly having P/N 65B90360-7: Thereafter at intervals not to exceed 12,000 flight cycles.
(2) Do the corrective actions in accordance with Parts 3, 4, and 5 of the service bulletin; except as provided by paragraph (i) of this AD.
(i) Where the service bulletin specifies to contact Boeing for appropriate action, do the corrective action using a method approved in accordance with paragraph (l) of this AD.
Reworking the lugs on the bulkhead fitting of the rear engine mount as specified in paragraphs (b)(2), (e), and (f) of AD 2001-15-15, amendment 39-12349, is acceptable for compliance with accomplishing the corrective action specified in “Part 3—Rear Engine Mount Bulkhead Inspection and Lug Overhaul and Upper Fitting Overhaul and Bolt Replacement” of the service bulletin.
At the applicable compliance times specified in Table 1 of this AD: Repetitively replace the thrust link of the rear engine mount of struts 1, 2, 3, and 4 with a new or overhauled thrust link, in accordance with Part 2 of the service bulletin; except as provided by paragraph (i) of this AD. During any replacement required by this paragraph, an existing thrust link may be replaced with a new or overhauled thrust link having P/N 65B90360-1, -4 or -7, provided that the applicable repetitive interval specified in Table 1 of this AD is complied with. If a fractured thrust link is found during any replacement or overhaul done in accordance with this paragraph: Before further flight, do the corrective actions specified in paragraph (h)(2) of this AD. Repetitive replacement of all thrust links having P/N 65B90360-1 or -4 terminates the repetitive inspections required by paragraph (g) of this AD. Accomplishing the repetitive replacement or overhaul of a thrust link required by paragraph (h) of this AD constitutes compliance with the requirements of this paragraph for that thrust link only.
| For thrust link P/N— | Initial replacement— | Repetitive interval— |
|---|---|---|
| 65B90360-1 or -4 | Within 36 months after the effective date of this AD | Thereafter at intervals not to exceed 6,000 flight cycles. |
| 65B90360-7 | Within 12,000 flight cycles after the new thrust link has been installed | Thereafter at intervals not to exceed 12,000 flight cycles. |
