AD 99-11-04 Airworthiness Directives; Sikorsky Aircraft Model S-76A Helicopters

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

Sikorsky Model S-76A helicopters with Turbomeca Arriel 1S1 engines installed in accordance with Supplemental Type Certificate SH568NE, including drawing number 76070-30601. 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, [[Page 33745]] 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.

Before further flight, unless accomplished previously. To reduce the published Category ``A'' maximum takeoff and landing gross weights and single-engine forward climb performance limitations of the Rotorcraft Flight Manual (RFM), when an AC generator interlock system is not installed, accomplish the following: (a) Insert Sikorsky Model S-76A RFM Supplement (RFMS) No. 29B, Temporary Revision 1, dated April 9, 1999, into RFMS No. 29B, dated December 21, 1993, or (b) Determine if the AC generator interlock relays are installed by conducting the following inspection: (1) Uncover the No. 2 Relay Panel, located in the right side of the cockpit overhead. This panel is also referred to as the right- hand panel. (2) Inspect for the presence of the AC generator interlock relays identified as K43 and K44 (two relays) or K46, K47, and K48 (three relays). Note 2: For S-76A helicopters, serial numbers (S/N's) 760001 through 760237, the AC generator interlock relays are wired through splice groups to the K31, K32, K11, and K13 relays. For S-76A helicopters, S/N's 760238 and higher, the AC generator interlock relays are wired through splice groups to the K11 and K13 relays. Depending on how and when each helicopter was modified, the labels on these relays could be K43 and K44 (two relays) or K46, K47, and K48 (three relays). Note 3: Sikorsky Aircraft Corporation Alert Service Bulletin 76- 77-4A, Revision A, dated May 5, 1999, pertains to the subject of this AD. (3) If the AC generator interlock relays are installed, no further action is required by this AD. (4) If the AC generator interlock relays are not installed, insert Sikorsky S-76A RFMS No. 29B, Temporary Revision 1, dated April 9, 1999, into RFMS No. 29B, dated December 21, 1993. (c) This AD revises the Limitations Section of the RFM for helicopters on which the AC generator interlock relays are not installed by inserting a new RFMS revision limiting Category ``A'' gross weight and reducing published climb performance. (d) Remove Sikorsky Model S-76A RFMS No. 29B, Temporary Revision 1, dated April 9, 1999, inserted into RFMS No. 29B, dated December 21, 1993, from the RFM upon installation of one of the following, as applicable: (1) For Model S-76A helicopters, S/N's 760001 through 760237, AC generator interlock kit (kit), part number (P/N) 33776-84790-012. (2) For Model S-76A helicopters, S/N's 760238 and higher, kit, P/N 33776-84790-011. (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, 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 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Boston 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 helicopter to a location where the requirements of this AD can be accomplished. (g) This amendment becomes effective on July 9, 1999, to all persons except those persons to whom it was made immediately effective by Priority Letter AD 99-11-04, issued May 13, 1999, which contained the requirements of this amendment. Issued in Fort Worth, Texas, on June 15, 1999. Henry A. Armstrong, Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 99-15901 Filed 6-23-99; 8:45 am] BILLING CODE 4910-13-U