Airworthiness Directive · Amendment 39-18562 · Engine/transmission coupling--coupling tube, engine mount, and engine mount base
Airbus Helicopters (Previously Eurocopter France) Helicopters
This AD applies to Model EC120B helicopters with an engine-to-main gearbox coupling tube assembly (coupling tube), part number (P/N) C631A1101101 or P/N C631A1002101, installed, certificated in any category.
We are superseding Airworthiness Directive (AD) 2000-05-17 and AD 2001-04-12, which apply to Eurocopter France (now Airbus Helicopters) Model EC120B helicopters. AD 2000-05-17 and AD 2001-04-12 required repetitive visual checks of the engine-to-main gearbox (MGB) coupling tube assembly (coupling tube) for a crack and replacing any cracked tube with an airworthy tube. This new AD requires removing certain engine mount parts from service, measuring the height of the engine mounting base for certain helicopters, replacing the engine mount if a certain height is exceeded, inspecting the flared coupling on certain helicopters for a crack, and replacing the coupling if it is cracked. Since we issued AD 2000-05-17 and AD 2001-04-12, there have been reports of additional cracks in coupling tubes. These actions are intended to prevent coupling tube failure, loss of engine drive, and a subsequent forced landing of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) For helicopters with a serial number up to and including 1169, not modified with an improvement of the engine mount in accordance with Eurocopter Service Bulletin (SB) No. 71-003, Revision 1, dated July 18, 2002 (SB 71-003), or not modified by installing a spring-type engine suspension system in accordance with Eurocopter SB No. 71-005, Revision 0, dated May 14, 2004 (SB 71-005), before further flight:
(i) Remove from service the following engine mount parts:
(A) Support arm, P/N C714A1107201;
(B) Swaged support arm, P/N C714A1106201;
(C) Left-hand support bracket, P/N C714A1101102; and
(D) Right-hand support bracket, P/N C714A1101103.
(ii) Measure the height of the engine mounting base as depicted in Figure 1 of Eurocopter Alert SB No. 04A005, Revision 0, dated July 16, 2003. If the height is more than 10.5 millimeters, replace the engine mount with an engine mount that does not have the parts identified in paragraph (f)(1)(i) of this AD.
(2) For helicopters with a serial number 1170 and larger or helicopters modified with an improvement of the engine mount in accordance with SB 71-003:
(i) Within 25 hours TIS, replace the spring-type engine suspension system and perform a dye-penetrant inspection of the flared coupling for a crack by following the Accomplishment Instructions, paragraphs 2.B.2.a through 2.B.2.c of SB 71-005.
(ii) If there is a crack in the flared coupling, before further flight, replace the coupling with an airworthy coupling.
(3) For helicopters with coupling tube, P/N C631A1002101, installed, before further flight, remove coupling tube, P/N C631A1002101, from service. Do not install coupling tube, P/N C631A1002101, on any helicopter.
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.
