AD 98-10-03 Airworthiness Directives; Allison Engine Company Model 250-C47B Turboshaft Engines

Models named: 250-C47B turboshaft, 407. Read the applicability below — it usually turns on serial or part numbers too.

Allison Engine Company Model 250-C47B turboshaft engines, installed on but not limited to Bell Helicopter Textron, A Division of Textron Canada Ltd. (BHTC) Model 407 helicopters. Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Required as indicated, unless accomplished previously. To prevent uncommanded inflight engine shutdowns, which can result in autorotation, forced landing, and possible loss of the helicopter, accomplish the following: (a) Prior to further flight, replace the engine main electrical harness assembly, part number (P/N) 23062796, with an improved assembly, P/N 23065805, in accordance with Allison Engine Company Alert Commercial Engine Bulletin (CEB) CEB-A-73-6010, dated October 15, 1996. (b) Prior to May 20, 1998, install a new hydromechanical control unit (HMU) and electronic control unit (ECU) in accordance with Allison Engine Company Alert CEB-A-73-6015, Revision 1, dated July 30, 1997, or Revision 2, dated October 31, 1997. (c) After completing the requirements of paragraph (b) of this AD, and prior to further flight: (1) Remove the ``OVRSPD SYSTEM INOP'' placard required by paragraph (d) of AD 96-24-09, and (2) Revise the FAA-approved Rotorcraft Flight Manual (RFM) by removing the pages added by paragraph (f) of AD 96-24-09, and incorporate BHTC RFM BHT-407-FM-1, Revision 5, dated June 24, 1997. (d) Within 45 days after the effective date of this AD, install a corrosion resistant electronic control unit (ECU) in accordance with Allison Engine Company Alert CEB-A-73-6017, Revision 1, dated February 18, 1998, or Revision 2, dated April 9, 1998. Installation of a corrosion resistant ECU in accordance with this paragraph will satisfy the requirement in paragraph (b) of this AD to install a new ECU. (e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Chicago Aircraft Certification Office. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Chicago Aircraft Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Chicago Aircraft Certification Office. (f) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished. (g) The actions required by this AD shall be done in accordance with the following service documents: [[Page 25391]] ---------------------------------------------------------------------------------------------------------------- Document No. Pages Revision Date ---------------------------------------------------------------------------------------------------------------- Allison Engine Company Alert, 1-7..................... Original................ October 15, 1996. CEB-A-73-6010. ---------------------------------------------------------------------------------------------------------------- Total pages: 7. ---------------------------------------------------------------------------------------------------------------- BHTC Rotorcraft Flight Manual Cover................... 5....................... June 24, 1997. BHT-407-FM-1. NP...................... 3....................... July 30, 1996. A,B..................... 5....................... June 24, 1997. C/D..................... 5....................... June 24, 1997. 1-3..................... 5....................... June 24, 1997. 1-4-1-7................. 4....................... November 4, 1996. 1-8..................... 5....................... June 24, 1997. 1-13.................... 4....................... November 4, 1996. 1-14.................... 5....................... June 24, 1997. 1-14A/14B............... 5....................... June 24, 1997. 1-19/1-20............... 5....................... June 24, 1997. 2-3..................... 5....................... June 24, 1997. 2-4..................... 1....................... March 8, 1996. 2-7-2-10................ 5....................... June 24, 1997. 2-13, 2-14.............. 5....................... June 24, 1997. 3-3-3-5................. 5....................... June 24, 1997. 3-6..................... 2....................... May 9, 1996. 3-7, 3-8................ 5....................... June 24, 1997. 3-15.................... 5....................... June 24, 1997. 3-16.................... 2....................... May 9, 1996. 3-17-3-22............... 5....................... June 24, 1997. 4-5, 4-6................ 5....................... June 24, 1997. 4-9..................... Original................ February 9, 1996. 4-10-4-12............... 5....................... June 24, 1997. ---------------------------------------------------------------------------------------------------------------- Total pages: 40. ---------------------------------------------------------------------------------------------------------------- Allison Engine Company Alert, 1-4..................... 1....................... July 30, 1997. CEB-A-73-6015. ---------------------------------------------------------------------------------------------------------------- Total pages: 4. ---------------------------------------------------------------------------------------------------------------- Allison Engine Company Alert, 1-4..................... 2....................... October 31, 1997. CEB-A-73-6015. ---------------------------------------------------------------------------------------------------------------- Total pages: 4. ---------------------------------------------------------------------------------------------------------------- Allison Engine Company Alert, 1-5..................... 1....................... February 18, 1998. CEB-A-73-6017. ---------------------------------------------------------------------------------------------------------------- Total pages: 5 ---------------------------------------------------------------------------------------------------------------- Allison Engine Company Alert, 1-5..................... 2....................... April 9, 1998. CEB-A-73-6017. ---------------------------------------------------------------------------------------------------------------- Total pages: 5 ---------------------------------------------------------------------------------------------------------------- (h) The incorporation by reference of Allison Engine Company Alert CEB-A-73-6010, dated October 15, 1996, CEB A-73-6015, Revision 1, dated July 30, 1997, and Revision 2, dated October 31, 1997, and BHTC RFM BHT-407-FM-1, Revision 5, dated June 24, 1997, was approved previously by the Director of the Federal Register as of December 3, 1997 (62 FR 61438, November 18, 1997). (i) The incorporation by reference of Allison Engine Company Alert CEB-A-73-6017, Revision 1, dated February 18, 1998, and Revision 2, dated April 9, 1998, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of May 26, 1998. (j) Copies of these service documents may be obtained from Allison Engine Company, P.O. Box 420, Speed Code P-40A, Indianapolis, IN 46206-0420; telephone (317) 230-2720, fax (317) 230-3381. Copies may be inspected at the FAA, New England Region, Office of the Regional Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. (k) This amendment becomes effective on May 26, 1998. Issued in Burlington, Massachusetts, on April 29, 1998. Thomas A. Boudreau, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 98-12063 Filed 5-7-98; 8:45 am] BILLING CODE 4910-13-U