2011-24-08: Backup Control Mode

Adoption of the Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: PART 39--AIRWORTHINESS DIRECTIVES 0 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. Sec. 39.13 [Amended] 0 2. The FAA amends Sec. 39.13 by adding the following new AD: 2011-24-08 Turbomeca S.A.: Amendment 39-16872; Docket No. FAA-2011- 1037; Directorate Identifier 2011-NE-30-AD. (a) Effective Date This airworthiness directive (AD) becomes effective December 7, 2011. (b) Affected ADs None. (c) Applicability This AD applies to Makila 1A2 turboshaft engines, all serial numbers. (d) Reason (1) This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes theunsafe condition as: A helicopter experienced an inadvertent activation of the 65% N1 (gas generator speed) back up control mode. The subsequent technical investigations carried by Turbomeca revealed that an N2 (power turbine speed) sensor harness wire crimping discrepancy was at the origin of this event. Further quality investigations performed with the supplier led to the conclusion that N2 sensor Part Number (P/N) 0 301 52 001 0 whose Serial Numbers (S/N) are between S/N 242 and S/N 339 inclusive are potentially concerned by the same manufacturing discrepancy. This condition, if not corrected, could lead to the inadvertent activation of the 65% N1 back up mode and consequently to significant power loss on one or more or both engines installed on the same helicopter, potentially resulting in an emergency landing of the helicopter. (2) We are issuing this AD to prevent inadvertent activation of the backup control mode, which could result in engine power loss and emergency landing of the helicopter. (e) Actions and Compliance (1) Unless already done, do the following actions. (2) For engines equipped with N2 sensor harnesses, P/N 0 301 52 001 0, whose S/Ns are between S/N 242 and S/N 339 inclusive, do the following: (i) If an affected P/N is installed on each of the 2 (two) engines of the helicopter, then within 10 flight hours (FHs) after the effective date of this AD, replace one N2 sensor harness with an N2 sensor harness that is eligible for installation, and within 50 FHs after the effective date of this AD, replace the second harness with an N2 sensor harness that is eligible for installation. (ii) If an affected P/N is installed only on 1 (one) engine of the helicopter, then within 50 FHs after the effective date of this AD, replace the affected N2 sensor harness with an N2 harness that is eligible for installation. (3) After the effective date of this AD, do not install in an engine any N2 sensor harness, P/N 0 301 52 001 0, whose S/N is between S/N 242 and S/N 339 inclusive, unless the part has ``SB 0815'' marked on the identification plate. (4) After the effective date of this AD, do not install in a helicopter an engine equipped with an N2 sensor harness, P/N 0 301 52 001 0, whose S/N is between S/N 242 and S/N 339 inclusive, unless the part has ``SB 0815'' marked on the identification plate. (f) Alternative Methods of Compliance (AMOCs) The Manager, Engine Certification Office, FAA, may approve AMOCs for this AD. Use the procedures found in 14 CFR 39.19 to make your request. (g) Related Information (1) Refer to MCAI EASA AD 2011-0147, dated August 5, 2011, and Turbomeca Service Bulletin No. 298 77 0817, for related information. Contact Turbomeca; 40220 Tarnos, France; phone: 33-05-59-74-40-00; fax: 33-05-59-74-45-11; for a copy of this service information. (2) Contact James Lawrence, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate,12 New England Executive Park, Burlington, MA 01803; email: james.lawrence@faa.gov; phone: (781)-238-7176; fax: (781) 238-7199, for more information about this AD. (h) Material Incorporated by Reference None.