Airworthiness Directive · Amendment 39-17654 · Turbomeca S.A. Turboshaft Engines
Turbomeca S.A. Turboshaft Engines
This AD applies to all Turbomeca S.A. Arriel 2D turboshaft engines.
We are superseding airworthiness directive (AD) 2013-01-07 for all Turbomeca S.A. Arriel 2D turboshaft engines. AD 2013-01-07 required replacing the hydromechanical metering unit (HMU) at a reduced life. This AD maintains that requirement and also requires conducting inspections of the HMU. This AD was prompted by further cases of deterioration of HMU rotating components. We are issuing this AD to prevent an uncommanded in-flight shutdown of the engine and possible loss of the helicopter.
(1) Replace inter-pump complete sleeve, and visually inspect the complete sleeve female splines and HMU high-pressure (HP) pump and low-pressure (LP) pump male splines for corrosion, scaling, cracks, and wear, at the following:
(i) Before exceeding 400 HMU operating hours since new if the HMU has 375 or fewer operating hours on the effective date of this AD; or
(ii) Within 25 HMU operating hours if the HMU has more than 375 operating hours on the effective date of this AD.
(iii) Thereafter, at intervals not to exceed 400 HMU operating hours.
(iv) Guidance on replacing the complete sleeve and inspecting the complete sleeve female splines, and HP and LP male splines, can be found in Turbomeca Technical Instruction No. 292 73 2847.
(v) If the HMU does not pass the initial or repetitive visual inspections required by paragraph (e)(1) of this AD, then before the next flight, replace the affected HMU with an HMU eligible for installation.
(2) Replace the rotating components of the HP and LP pumps, including the complete sleeve, or replace the HMU with an HMU eligible for installation at the following:
(i) Before exceeding 800 HMU operating hours since new; or
(ii) Within 800 HMU operating hours since last replacement of LP and HP fuel pumps rotating components; whichever occurs later.
(iii) Thereafter, replace the LP and HP fuel pump rotating components or the HMU within every 800 HMU operating hours.
(iv) Guidance for completing the requirements of paragraph (e)(2) can be found in Turbomeca S.A. Alert Mandatory Service Bulletin (MSB) No. A292 73 2847.
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.
