Airworthiness Directive · Amendment 39-11731 · Eurocopter Deutschland GmbH (Eurocopter) Model EC 135 Helicopters
Eurocopter Deutschland GmbH (Eurocopter) Model EC 135 Helicopters
Model EC 135 helicopters, serial numbers 0005 through 0071, 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 (e) 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 Model EC 135 helicopters. This AD requires replacing a certain oil cooler fan splined drive shaft (shaft) with a different airworthy shaft and re-identifying the part numbers on the oil cooler fans. This amendment is prompted by two incidents in which the shaft broke. The actions specified by this AD are intended to prevent failure of the shaft, loss of oil cooling, and a subsequent engine shutdown during flight.
To prevent failure of an oil cooler fan splined drive shaft (shaft), loss of oil cooling, and a subsequent engine shutdown during flight, accomplish the following:
(a) Replace each shaft, part number (P/N) L 792M3004 225, with an airworthy shaft, P/N L 792M3004 235.
(b) Re-identify the P/N on each oil cooler fan (fan) using a rubber stamp or smudge-proof paint or equivalent as follows:
(1) On the left fan, change the P/N from L 792M3004 102 to L 792M3004 103.
(2) On the right fan, change the P/N from L 792M3005 102 to L 792M3005 103.
(c) Change the P/N on the gearbox component history card or equivalent record to reflect the revised part numbers.
Note 2: Eurocopter Alert Service Bulletin No. EC 135-79A-001, dated January 23, 1998, pertains to the subject of this AD.
(d) Replacing the shaft, re-identifying the fans, and recording this on the gearbox component history card or equivalent record constitute terminating actions 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.
