Airworthiness Directive · Amendment 39-11675 · McDonnell Douglas Model MD-11 Series Airplanes
McDonnell Douglas Model MD-11 Series Airplanes
Model MD-11 series airplanes, as listed in McDonnell Douglas Alert Service Bulletin MD11-24A116, Revision 01, dated October 11, 1999; except for those airplanes on which the modification specified in McDonnell Douglas Service Bulletin MD11-24-116, dated May 14, 1997, has been accomplished; certificated in any category.
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (c) 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), applicable to certain McDonnell Douglas Model MD-11 series airplanes, that requires a general visual inspection of wiring behind the control panel of the auxiliary power unit (APU) located in the cockpit to detect chafing; repair if necessary; and modification of the wiring. This amendment is prompted by an incident of chafing of wire bundles of the control module of the APU. The actions specified by this AD are intended to prevent such chafing and resultant arcing due to insufficient clearance between the wire bundles and the airplane structure, which could result in smoke and fire in the flight deck.
To prevent wire chafing of the control panel of the auxiliary power unit (APU) and resultant arcing due to insufficient clearance between the wire bundles and the airplane structure, which could result in smoke and fire in the flight deck, accomplish the following:
(a) Within 12 months after the effective date of this AD, perform a general visual inspection of wiring behind the control panel of the APU to detect chafing, in accordance with McDonnell Douglas Alert Service Bulletin MD11-24A116, Revision 01, dated October 11, 1999.
Note 2: For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”
(1) If no chafing is found, prior to further flight, accomplish the requirements of paragraph (b) of this AD.
(2) If any chafing is found, prior to further flight, repair in accordance with the service bulletin and accomplish the requirements of paragraph (b) of this AD.
(b) Modify the wiring behind the APU control panel (i.e., install sleeving and fiber tying tape over wires) in accordance with McDonnell Douglas Alert Service Bulletin MD11-24A116, Revision 01, dated October 11, 1999.
