AD 2014-07-06

This AD is effective May 15, 2014.

This AD supersedes AD 2007-19-09R1, Amendment 39-16322 (75 FR 30687, June 2, 2010).

This AD applies to Turbomeca S.A. Arriel 2B1 turboshaft engines that do not have modification TU157 incorporated.

This AD was prompted by reports of ruptures on hydromechanical metering unit (HMU) constant delta pressure valves that have less than 2,000 hours in service. We are issuing this AD to prevent failure of the HMU, which could lead to damage to the engine, and damage to the aircraft.

Comply with this AD within the compliance times specified, unless already done.

(1) HMU operating hours and power turbine C2 cycles are known:

(i) If on the effective date of this AD, the HMU C2 cycles are less than 900, then replace the HMU before the HMU accumulates 1,000 C2 cycles or 1,500 HMU operating hours, whichever occurs first;

(ii) If on the effective date of this AD, the HMU C2 cycles are 900 or more, then replace the HMU within 100 HMU C2 cycles after the effective date of this AD;

(iii) Thereafter, replace the HMU at every 1,000 HMU C2 cycles or 1,500 HMU operating hours, whichever comes first.

(2) HMU operating hours are known and C2 cycles are not known:

(i) If on the effective date of this AD, the HMU operating hours are less than 1,100, then replace the HMU before accumulating 1,200 HMU operating hours;

(ii) If on the effective date of this AD, the HMU operating hours are 1,100 or more, then replace the HMU within 100 HMU operating hours after the effective date of this AD;

(iii) Thereafter, replace the HMU at every 1,200 HMU operating hours.

For the purpose of this AD, HMU operating hours or C2 cycles are defined as operating hours or C2 cycles since new, since overhaul, or since incorporation of Turbomeca S.A. Service Bulletin (SB) No. 292 73 2105, Version B, dated December 16, 2010, or earlier version, or Turbomeca S.A. Mandatory SB (MSB) No. 292 73 2818, Version D, dated June 24, 2013, or earlier version.

Incorporation of Turbomeca S.A. SB No. 292 73 2157, Version C, dated July 17, 2013, or earlier version, is terminating action to the replacement and repetitive inspection requirements of this AD.

If you performed the actions required by paragraphs (e)(1) or (e)(2) of this AD using an earlier version of Turbomeca S.A. MSB No. 292 73 2818, Version D, dated June 24, 2013, you met the requirements of this AD. However, you must still repetitively replace the HMU as required by paragraphs (e)(1)(iii) and (e)(2)(iii) of this AD.

The Manager, Engine Certification Office, FAA, may approve AMOCs to this AD. Use the procedures found in 14 CFR 39.19 to make your request.

(1) For more information about this AD, contact James Gray, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; phone: 781-238-7742; fax: 781-238-7199; email: james.e.gray@faa.gov.

(2) Refer to MCAI European Aviation Safety Agency AD 2013-0171, dated July 30, 2013. You may examine the MCAI in the AD docket on the Internet at http://www.regulations.gov/#!documentDetail;D=FAA-2007-27009-0015.

(3) Turbomeca S.A. MSB No. 292 73 2818, Version D, dated June 24, 2013, Turbomeca S.A. SB No. 292 73 2157, Version C, dated July 17, 2013, and Turbomeca S.A. SB No. 292 73 2105, Version B, dated December 16, 2010, which are not incorporated by reference in this AD, can be obtained from Turbomeca S.A. using the contact information in paragraph (j)(4) of this AD.

(4) For service information identified in this AD, contact Turbomeca, S.A., 40220 Tarnos, France; phone: 33 (0)5 59 74 40 00; telex: 570 042; fax: 33 (0)5 59 74 45 1.

(5) You may view this service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA. For information on the availability of this material at the FAA, call 781-238-7125.

None.