Airworthiness Directive · Amendment 39-11579 · Bell Helicopter Textron Canada Model 407 Helicopters
Bell Helicopter Textron Canada Model 407 Helicopters
Superseded. A later AD replaced this one: AD 2002-06-52. Comply with the one in force.
Model 407 helicopters, with oil cooler blower shaft bearing (bearing), part number (P/N) 407-340-339-101 or -103, 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 document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2000-02-12, which was sent previously to all known U.S. owners and operators of Bell Helicopter Textron Canada (BHTC) Model 407 helicopters by individual letters. This AD requires inspecting engine oil cooler blower shaft bearings (bearings) for roughness at specified time intervals and replacing any rough bearings before further flight. This amendment is prompted by several bearing failures. The actions specified by this AD are intended to prevent bearing failure, loss of tail rotor drive, and a subsequent forced landing.
To prevent bearing failure, loss of tail rotor drive, and a subsequent forced landing, accomplish the following:
(a) Within 10 hours time-in-service (TIS), inspect the forward and aft bearings for roughness by hand-rotating the driveshaft with the oil cooler driveshaft connected. Replace any rough bearing before further flight.
(b) Within 25 hours TIS, inspect the forward and aft bearings for roughness by hand-rotating the driveshaft with the oil cooler driveshaft disconnected at both ends. Replace any rough bearing before further flight. After the inspection, lubricate the bearings with MIL-G-25013 grease.
(c) Following the inspection of paragraph (b) and at intervals not to exceed 25 hours TIS, repeat the inspection of paragraph (a). Replace any rough bearing before further flight. After each recurring inspection, lubricate the bearings with MIL-G-25013 grease.
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.
