Airworthiness Directive · Amendment 39-11702 · Eurocopter Deutschland GMBH Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
Eurocopter Deutschland GMBH Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, serial numbers 7001 through 7253 and 7500 through 7523, with transmission door cowling, left hand, part number (P/N) 117-23206-51 or 117-233731, right hand, P/N 117-23206-52 or 117-233741, and engine door cowling left hand, P/N 117-23303-51 or 117-23303-53, right hand, P/N 117-23303-52 or 117-23303-54, installed, certificated in any category.
Note 1: This AD applies to each helicopter 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 helicopters 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 applies to Eurocopter Deutschland GMBH (ECD) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters. This AD requires modifying the engine and transmission cowling doors (cowling doors). This amendment is prompted by an emergency landing of an ECD Model MBB-BK 117 helicopter after the No. 1 engine cowling opened, separated from the helicopter, and struck the main and tail rotor blades resulting in a tail rotor imbalance and subsequent departure of the tail rotor gear box from the helicopter. The actions specified by this AD are intended to prevent the cowling doors opening during flight, separating from the helicopter and impacting the main or tail rotor blades, and subsequent loss of control of the helicopter.
To prevent the engine and transmission cowling doors (cowling doors) opening during flight, separating from the helicopter and impacting the main or tail rotor blades, and subsequent loss of control of the helicopter, accomplish the following:
(a) Modify the cowling doors in accordance with paragraph 2.B., Work Procedure, and 2.C., Conclusions, of Eurocopter Deutschland GMBH Service Bulletin SB-MBB-BK 117-20-109, Revision 2, dated April 30, 1999 (SB).
Note 2: Adjustment and functional testing of the hook system in accordance with paragraph 2.B.8 of the SB is critical after installation.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
