AD 99-07-01 Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model S-76C Helicopters

Models named: S-76C. Read the applicability below — it usually turns on serial or part numbers too.

Model S-76C helicopters, with Turbomeca Arriel 2S1 engines with an engine Hydromechanical Unit (HMU), part number 0.292.92.822.0, 0.292.92.808.0, 0.292.92.813.0, or 0.292.92.828.0, installed, certificated in any category. Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters 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 (c) 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 before further flight, unless accomplished previously. To prevent an inability to achieve the published One-Engine Inoperative performance and subsequent loss of the helicopter, accomplish the following: (a) Insert the following into the Operating Limitations section and Performance Data section, as appropriate, of Rotorcraft Flight Manual (RFM) SA 4047-76C-10: RFM (Basic), original approval date June 19, 1996, Revision 7, dated February 1, 1999; RFM Supplement No. 8, original approval date August 28, 1997, Revision 1, dated February 1, 1999; and RFM Supplement No. 9, original approval date August 28, 1997, Revision 1, dated February 1, 1999. (b) This AD revises the Operating Limitations section and Performance Data section of the RFM by requiring lower allowable gross weights for certain operational conditions. (c) 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, Boston Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Boston Aircraft Certification Office. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Boston Aircraft Certification Office. (d) 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 helicopter to a location where the requirements of this AD can be accomplished. (e) This amendment becomes effective on April 7, 1999. Issued in Fort Worth, Texas, on March 12, 1999. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 99-6977 Filed 3-22-99; 8:45 am] BILLING CODE 4910-13-U