Airworthiness Directive · Amendment 39-21259 · Main rotor drive indicating system
Airbus Helicopters
This AD applies to Airbus Helicopters Model AS350B2 helicopters, certificated in any category, with a main rotor RPM (NR) sensor part number 704A37614007 installed.
The FAA is adopting a new airworthiness directive (AD) for certain Airbus Helicopters Model AS350B2 helicopters. This AD requires performing a test of the main rotor RPM (NR) indicator, and depending on the results, altering the wiring. This AD was prompted by reports of some NR indicators displaying incorrect information. The actions of this AD are intended to address an unsafe condition on these products.
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.
Before further flight, perform a ground run-up with the fuel flow control lever in the flight gate with the collective control in the down/locked position. While at flight NR speed, activate the emergency cut-out control and observe the NR indicator display value. If the NR indicator display changes or drops to zero, before further flight, do the following:
(1) Alter the NR indicator wiring as depicted in Figures 1 and 2 of Airbus Helicopters Alert Service Bulletin No. AS350-63.00.27, Revision 0, dated May 17, 2016; and,
Note 1 to paragraph (e)(1): Airbus Helicopters identifies the alteration of the wiring as Modification 350A084886.00.
(2) Conduct a continuity test to confirm correct alteration of the wiring.
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.
