Airworthiness Directive · Amendment 39-11831 · Boeing Model 747-400 Series Airplanes
Boeing Model 747-400 Series Airplanes
Model 747-400 series airplanes having line numbers (L/N) 1162 through 1223, except L/N 1174; equipped with horizontal stabilizer fuel tanks; 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 (b) 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 747-400 series airplanes. This action requires a one-time inspection to determine if certain wire bundles are routed incorrectly and to detect damage, and corrective actions, if necessary. This action is necessary to prevent damage of certain wire bundles routed to the fuel tank transfer pumps in the horizontal stabilizer, which could result in electrical arcing and a possible fire adjacent to the fuel tank. This action is intended to address the identified unsafe condition.
To prevent damage of certain wire bundles routed to the fuel tank transfer pumps in the horizontal stabilizer, which could result in electrical arcing and a possible fire adjacent to the fuel tank, accomplish the following:
(a) Within 60 days after the effective date of this AD, perform a one-time detailed visual inspection of wire bundles routed to the fuel tank transfer pumps in the horizontal stabilizer to determine if wire bundles W4601 and W4602 are routed correctly and to detect damage, in accordance with Boeing Alert Service Bulletin 747-28A2232, Revision 1, dated June 22, 2000.
(1) If the wire bundles are routed correctly and no damage is detected, no further action is required by this AD.
(2) If either wire bundle is determined to be incorrectly routed, but no damage is detected, prior to further flight, reroute the affected wire bundle in accordance with the alert service bulletin.
(3) If any damage is detected (whether the wire bundles are routed properly or not), prior to further flight, repair the affected wire bundle and route the wire bundle correctly, as applicable, in accordance with the alert service bulletin.
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.”
Note 3: Inspections and corrective actions accomplished prior to the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-28A2232, dated March 2, 2000, are considered acceptable for compliance with the applicable action specified in this amendment.
