AD 94-14-20 R1

This amendment revises an existing airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A helicopters. That AD currently requires a one-time inspection of the tail rotor blade (blade) spar elliptical centering plug (centering plug) for disbonding and the addition of a retaining pad on the pitch change shaft between the output tail rotor gearbox flange and the inboard tail rotor spar. This amendment contains the same requirements as the existing AD but clarifies that the 500-hour time-in-service (TIS) repetitive inspections, which could cause inadvertent damage, are not required. This AD also incorporates by reference a revised alert service bulletin (ASB) that does not include the 500-hour TIS repetitive inspections. This amendment is prompted by operator confusion about whether the current AD continues to require the 500- hour TIS repetitive inspections. The actions specified by this AD are intended to verify that the FAA has determined that the500-hour TIS repetitive inspections are not required to prevent the centering plug from disbonding and moving out of position, loss of tail rotor control, and subsequent loss of control of the helicopter.

Final rule.

94-14-20 R1 Sikorsky Aircraft Corporation: Amendment 39-12216. Docket No. 2000-SW-40-AD. Revises AD 94-14-20, Amendment 39-8969, Docket No. 93-SW-13-AD.

Applicability: Model S-76A helicopters, with tail rotor blade (blade) assembly, part number (P/N) 76101-05001 (all dash numbers) or 76101-05101 (all dash numbers), installed with more than 130 hours time-in-service (TIS), 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 within 25 hours TIS, unless accomplished previously.

To prevent the blade spar elliptical centering plug (centering plug) from disbonding and moving out of position, loss of tail rotor control, and subsequent loss of control of the helicopter, accomplish the following:

(a) Inspect the centering plug for disbonding of the polyurethane filler that fills the space between the aluminum centering plug and the graphite spar in accordance with the Accomplishment Instructions, paragraph 3.A.(1) and (2), of Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-65-35B (153B), Revision B, dated October 2, 1997 (ASB).

Note 2: The 500-hours TIS repetitive inspections contained in the Accomplishment Instructions, paragraph 3.D., of Sikorsky Aircraft Corporation Alert Service Bulletin 76-65-35A,Revision A, dated February 29, 1984, are not required by this AD.

(1) If the inspection of the centering plug reveals disbonding of \1/2\-inch or less in length, install a retaining pad, P/N 76102- 05004-111, in accordance with the Accomplishment Instructions, paragraph 3.C., of the ASB.

(2) For disbonds greater than \1/2\-inch in length, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(1), of the ASB except you are not required to contact Sikorsky Worldwide Customer Service. If blades are found with polyurethane filler excessively cracked or deteriorated to extent of breaking away from the spar or aluminum plug by 0.005-inch or greater, replace the blade with an airworthy blade.

(3) For spars with complete spar to centering plug disbond in which the polyurethane filler is intact and remains fully bonded to the centering plug, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(2), of the ASB.

(4) For spars with complete polyurethane filler to centering plug disbond in which the polyurethane filler is intact and remains fully bonded to the spar, repair the blade assembly in accordance with the Accomplishment Instructions, paragraph 3.B.(3) of the ASB.

(b) Install a retaining pad, P/N 76102-05004-111, in accordance with the Accomplishment Instructions, paragraph 3.C., of the ASB.

(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 3: 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) Specialflight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished if a retaining pad has been installed.

(e) The inspections, modifications, and repair shall be done in accordance with the Accomplishment Instructions, paragraphs 3.A.(1), 3.A.(2), 3.B.(1), 3.B.(2), 3.B.(3), and 3.C., of Sikorsky Aircraft Corporation Alert Service Bulletin No. 76-65-35B (153B), Revision B, dated October 2, 1997. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Sikorsky Aircraft Corporation, Attn: Manager, Commercial Tech Support, 6900 Main Street, Stratford, Connecticut 06614, phone (203) 386-3001, fax (203) 386-5983. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on June 8, 2001.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by revising AD 94-14-20, Amendment 39-8969 (59 FR 41238, August 11, 1994), which applies to Sikorsky Model S-76A helicopters, was published in the Federal Register on January 30, 2001 (66 FR 8184). The action proposed to require a one- time inspection of the blade centering plug for disbonding and the addition of a retaining pad on the pitch change shaft between the output tail rotor gearbox flange and the inboard tail rotor spar. The action also clarified that 500-hour TIS repetitive inspections, which could cause inadvertent damage, are not required and proposed to incorporate by reference a revised ASB that does not include the 500- hour TIS repetitive inspections.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for some editorial changes that are made in paragraphs (a) and (e). These changes were made to better identify the service information that is incorporated by reference. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

The FAA estimates that this AD will affect 150 helicopters of U.S. registry. This revised AD will not impose any additional burden or costs.

The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. Section 39.13 is amended by removing Amendment 39-8969 (59 FR 41238, August 11, 1994), and by adding a new airworthiness directive (AD), Amendment 39-12216, to read as follows: