AD 2000-23-51

AIRWORTHINESS DIRECTIVES EMERGENCY RULES: 2000-23-51

CITATION: This information is not available.

PAGE NUMBER:

DOCKET NUMBER: 2000-SW-59-AD

AMENDMENT:

AD NUMBER: 2000-23-51

SUBJECT HEADING: Sikorsky Model S-76A, S-76B, and S-76C Helicopters

ACTION:

SUMMARY:

DATES:

ADDRESSES:

FOR FURTHER INFORMATION CONTACT: Wayne Gaulzetti, Aviation Safety Engineer, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, MA 01803, telephone (781) 238-7156, fax (781) 238-7199.

SUPPLEMENTARY INFORMATION: DATE: November 3, 2000 2000-23-51

Send to all U.S. owners and operators of Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C helicopters.

This Emergency Airworthiness Directive (AD) is prompted by the discovery of a cracked main rotor shaft assembly (shaft) during an inspection of the main transmission oil seal. The shaft had accrued 477 hours time-in-service (TIS) when the crack was found. This condition, if not corrected, could result in failure of the shaft and subsequent loss of control of the helicopter.

The FAA has reviewed Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-66-31, dated November 1, 2000, which describes procedures for a one-time fluorescent penetrant inspection of the shaft, part number 76351-09030 series or 76351-09630 series.

Since an unsafe condition has been identified that is likely to exist or develop on other Sikorsky Aircraft Corporation Model S-76A, S-76B, and S-76C helicopters of the same type design, this AD requires, before further flight, performing a fluorescent penetrant inspection of the shaft in the area above the upper shaft output seal and below the lower hub attachment flange. If any crack is found, the shaft must be replaced with an airworthy shaft that has been inspected in accordance with the requirements of this AD. The actions are required to be accomplished in accordance with the alert service bulletin described previously.

This rule is issued under 49 U.S.C. Section 44701 pursuant to the authority delegated to me by the Administrator, and is effective immediately upon receipt of this emergency AD.

REGULATORY TEXT: 2000-23-51 SIKORSKY AIRCRAFT CORPORATION: Docket No. 2000-SW-59-AD. Applicability: Model S-76A, S-76B, and S-76C helicopters, with main rotor shaft assembly (shaft), part number (P/N) 76351-09030 series or 76351-09630 series, 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.

Compliance: Required before further flight, unless accomplished previously.

To prevent failure of the shaft and subsequent loss of control of the aircraft, accomplish the following:

(a) Perform a fluorescent penetrant inspection of the shaft in the area above the upper shaft output seal and below the lower hub attachment flange in accordance with the Accomplishment Instructions, paragraph 3.A.(1) through 3.A.(8), contained in Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-66-31, dated November 1, 2000.

(b) If a crack is found, remove the shaft and replace it with an airworthy shaft that has been inspected in accordance with the requirements of this AD.

(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 if no crack is found following a visual inspection of the shaft using a 10x or higher magnifying glass. If there is a crack, no special flight permit will be issued.

(e) Copies of the applicable service information may be obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Tech Support, 6900 Main Street, Stratford, Connecticut 06614, phone (203) 386-7860, fax (203) 386-4703.

(f) Emergency AD 2000-23-51, issued November 3, 2000, becomes effective upon receipt.

FOOTER: Issued in Fort Worth, Texas on November 3, 2000. Larry M. Kelly, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.