Airworthiness Directive · Amendment 39-11886 · Boeing Model 747 Series Airplanes Powered By Pratt & Whitney JT9D-7 Series Engines
Boeing Model 747 Series Airplanes Powered By Pratt & Whitney JT9D-7 Series Engines
Superseded. A later AD replaced this one: AD 2001-15-15. Comply with the one in force.
Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines, as listed in Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; 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 (d) 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 adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines. This action requires inspection of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. This action is necessary to detect and correct bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, which could result in separation of the engine from the airplane. This action is intended to address the identified unsafe condition.
To detect and correct bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, accomplish the following:
(a) At the later of the times in paragraphs (a)(1) and (a)(2) of this AD, perform a detailed visual inspection for bushing migration, corrosion, or cracking; and a physical measurement inspection using feeler gages for bushing migration; of the lugs on the bulkhead fitting of the rear engine mount, in accordance with Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000. Thereafter, repeat the inspection at intervals not to exceed 90 days, except as provided by paragraph (c) of this AD.
(1) Prior to the accumulation of 10,000 total flight cycles, or within 15 years since the date of manufacture of the airplane, whichever occurs first.
(2) Within 90 days after the effective date of this AD.
Note 2: 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.”
(b) During any inspection accomplished in accordance with paragraph (a) or (c) of this AD, if bushing migration, corrosion, or cracking is detected, accomplish paragraph (b)(1) or (b)(2) of this AD, as applicable.
(1) If light corrosion or bushing migration is found: Prior to further flight, do interim rework in accordance with Part 4 of the service bulletin; EXCEPT where the service bulletin specifies to contact Boeing, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; 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 approval letter must specifically reference this AD.
Note 3: The ultrasonic inspection described in Part 3 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, and the rework described in Part 5 are not required by paragraph (b)(1) of this AD. However, the repetitive detailed visual inspections required by paragraph (a) of this AD continue to be required.
(2) If moderate to severe corrosion or any cracking is found: Prior to further flight, rework 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 approval letter must specifically reference this AD.
(c) Accomplishment of the repetitive ultrasonic inspections specified in Part 3 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, at intervals not to exceed 1,400 flight cycles or 18 months, whichever occurs first; extends the interval for the repetitive detailed visual and physical measurement inspections required by paragraph (a) of this AD to the interval stated in paragraph (c)(1) or (c)(2) of this AD, as applicable.
(1) If no bushing migration is found, the repetitive interval is not to exceed 1,400 flight cycles or 18 months, whichever occurs first.
(2) If any bushing migration is found, the repetitive interval is not to exceed 180 days.
