Airworthiness Directive · Amendment 39-11603 · Bell Helicopter Textron Canada Model 407 Helicopters
Bell Helicopter Textron Canada Model 407 Helicopters
Model 407 helicopters, serial numbers 53000 through 53266, inclusive, 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), applicable to Bell Helicopter Textron Canada (BHTC) Model 407 helicopters, that requires replacing a certain hydraulic relief valve (valve) with a different valve. This amendment is prompted by the discovery of a manufacturing defect in a valve. The actions specified by this AD are intended to prevent intermittent loss of hydraulic pressure to the flight controls and subsequent loss of control of the helicopter.
To prevent intermittent loss of hydraulic pressure to the flight controls and subsequent loss of control of the helicopter, accomplish the following:
(a) Remove the hydraulic relief valve (valve), part number (P/N) 206-076-036-101, and replace it with an airworthy valve, P/N 206-076-036-105, in accordance with the Accomplishment Instructions in Bell Helicopter Textron Alert Service Bulletin No. 407-98-20, dated July 3, 1998.
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.
