Airworthiness Directive · Amendment 39-11517 · Eurocopter Deutschland GMBH Model EC 135 P1 and EC 135 T1 Helicopters
Eurocopter Deutschland GMBH Model EC 135 P1 and EC 135 T1 Helicopters
Model EC 135 P1 and EC 135 T1 helicopters, with main rotor blades up to and including serial number 834, 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 (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) applicable to Eurocopter Deutschland GMBH (ECD) Model EC 135 P1 and EC 135 T1 helicopters. This action requires inspecting main rotor expansion bolt safety wires, bolt heads, and bolt nuts; replacing any unairworthy expansion bolt with a hexagon bolt; and, as necessary, replacing any bolt nut before further flight. This AD also requires replacing each expansion bolt, regardless of condition, no later than January 31, 2000. This amendment is prompted by reports of main rotor blade expansion bolt nuts becoming loose. This condition, if not corrected, could result in severe vibration during flight and subsequent loss of control of the helicopter.
To prevent a main rotor blade expansion bolt nut becoming loose, causing severe vibration during flight, and subsequent loss of control of the helicopter, accomplish the following:
(a) Before further flight and thereafter at intervals not to exceed 15 hours time-in-service, visually inspect the main rotor blade expansion bolt safety wire, bolt head, and bolt nut in accordance with the Accomplishment Instructions, paragraph 3.A., steps (1), (2), (3), (4), and (6) of Eurocopter Deutschland GMBH (ECD) Alert Service Bulletin EC 135-62A-005, Revision 1, dated November 16, 1999 (ASB). If the safety wire is improperly fitted, the bolt head is worn, the expansion bolt thread does not protrude through the end of the nut, the bolt head has metallic abrasions, the nut is loose, or the nut has metallic abrasions, before further flight, replace the expansion bolt, part number (P/N) L621M1010 223, with a hexagon bolt, P/N L621M1010 222, and, as necessary, replace the nut in accordance with paragraph 3.B. of the ASB.
(b) Replace all expansion bolts, P/N L621M1010 223, with hexagon bolts, P/N L621M1010 222, and, as necessary, replace the nuts before flight after January 31, 2000.
(c) Replacing the expansion bolts with hexagon bolts and replacing the nuts, as necessary, constitutes terminating action for the requirements of this AD.
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.
