AD 2015-26-10 Airworthiness Directives; Sikorsky Aircraft Corporation Helicopters

This AD becomes effective February 9, 2016.

(1) The Manager, Boston Aircraft Certification Office, FAA, may approve AMOCs for this AD. Send your proposal to: Kirk Gustafson, Aviation Safety Engineer, Boston Aircraft Certification Office, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, Massachusetts 01803; telephone (781) 238-7190; email kirk.gustafson@faa.gov. (2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office before operating any aircraft complying with this AD through an AMOC.

Sikorsky Overhaul and Repair Instruction No. 76350-065, dated November 12, 1982; Revision A, dated September 21, 1984; Revision B, dated June 10, 2011; Revision C, dated June 27, 2011; Revision D, dated January 20, 2012; Revision E, dated January 27, 2012; and Revision F, dated May 10, 2012, which are not incorporated by reference, contain additional information about the subject of this AD. You may review a copy of this service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, Texas 76177.

(1) Within 50 hours time-in-service (TIS), and thereafter at intervals not to exceed 6 hours TIS, inspect each MGB lower housing jet bore (jet bore), as depicted in Figures 3 and 4 of Sikorsky S-76 Alert Service Bulletin 76-66-50, Basic Issue, dated January 14, 2013 (ASB 76-66-50), for liner protrusion or movement, paint or caulk blistering, or oil leakage. (i) If there is any liner protrusion or movement, before further flight, replace the MGB with an MGB that has not been repaired in accordance with ORI 76350-065 or ORI 76350-065A, unless it has been subsequently repaired in accordance with Sikorsky ORI No. 76350-065, Revision B, dated June 10, 2011 (ORI 76350-065B); Sikorsky ORI No. 76350-065, Revision C, dated June 27, 2011 (ORI 76350-065C); Sikorsky ORI No. 76350-065, Revision D, dated January 20, 2012 (ORI 76350-065D); Sikorsky ORI No. 76350-065, Revision E, dated January 27, 2012 (ORI 76350-065E); or Sikorsky ORI No. 76350-065, Revision F, dated May 10, 2012 (ORI 76350-065F). (ii) If there is any oil leakage or paint or caulk blistering, inspect the jet bore for liner protrusion and perform a leakage check by following the Accomplishment Instructions, Paragraphs 3.C.(1) through 3.C.(6)(a), of ASB 76-66-50. (iii) If any moisture or droplets of MGB oil are visible on a jet bore after accomplishing the leakage check specified in paragraph 3.C.(6)(a) of ASB 76-66-50, repeat paragraphs 3.C(4) through 3.C(6) of ASB 76-66-50. If any moisture or droplets of MGB oil are still visible, before further flight, replace the MGB with an MGB that has not been repaired in accordance with ORI 76350-065 or ORI 76350-065A, unless it has been subsequently repaired in accordance with ORI 76350-065B, ORI 76350-065C, ORI 76350-065D, ORI 76350-065E, or ORI 76350-065F. (2) Within 3,750 hours TIS, replace the MGB with an MGB that has not been repaired in accordance with ORI 76350-065 or ORI 76350-065A, unless it has been subsequently repaired in accordance with ORI 76350-065B, ORI 76350-065C, ORI 76350-065D, ORI 76350-065E, or ORI 76350-065F. This is terminating action for the repetitive inspections required by this AD.

This AD defines the unsafe condition as an unsecured MGB lower housing jet bore liner. This condition may cause the liner to move out of place, allowing oil to leak from the MGB, resulting in MGB failure and subsequent loss of control of the helicopter.