Airworthiness Directive · Amendment 39-16439 · Turboméca S.A. ARRIEL 2B Turboshaft Engines
Turboméca S.A. ARRIEL 2B Turboshaft Engines
This AD applies to Turboméca S.A. ARRIEL 2B turboshaft engines that do not have Modification TU 149 incorporated. These engines are installed on, but not limited to, Eurocopter AS350B3 helicopters.
The FAA is superseding an existing airworthiness directive (AD) for Turbom[eacute]ca S.A. ARRIEL 2B turboshaft engines. That AD currently requires initial and repetitive inspections, cleaning, lubrication, and checks for proper operation of the hydro-mechanical unit (HMU) acceleration controller axle except on engines that incorporate modification TU 132. That AD also provides an optional terminating action for the repetitive inspections. This AD requires the same actions, but expands the applicability to include all engines that do not incorporate modification TU 149. This AD results from reports of engines with modification TU 132 incorporated experiencing stuck controller axles in the metering valve body. We are issuing this AD to prevent loss of control of engine fuel flow in manual control mode or mixed control mode, which can lead to engine overspeed, and in-flight engine shutdown resulting in a forced autorotation landing or accident.
You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.
Within 20 operating hours of the effective date of this AD, check the fuel metering system and perform maintenance procedures in accordance with Paragraph 2 of Turboméca MSB A292 73 2814, Version D, dated October 16, 2009.
(g) Repeat the maintenance procedures of paragraph (f) of this AD within every 210 operating hours.
Modifying the HMU to Modification TU 149 terminates the repetitive inspection requirements specified in paragraph (g) of this AD. You can find guidance on modifying the HMU to Modification TU 149 in Turboméca Service Bulletin 292 73 2149, Version C, dated August 10, 2009.
(i) Maintenance performed prior to the effective date of this AD using Turboméca MSB A292 73 2814, Version C, dated December 19, 2006, or an earlier version of this MSB, satisfies the maintenance requirements of paragraph (f) of this AD.
