2021-05194. Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Helicopters

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Proposed rule; withdrawal.

SUMMARY:

The FAA is withdrawing a notice of proposed rulemaking (NPRM) that proposed to adopt a new airworthiness directive (AD) that would have applied to certain Sikorsky Model S-92A helicopters. The NPRM was prompted by a fatigue analysis conducted after a helicopter was found with a severed main gearbox (MGB) mounting foot pad (foot pad) that failed due to fatigue. The NPRM would have required revising the airworthiness limitations section of the existing Instructions for Continued Airworthiness (ICA) for your helicopter to reduce the life limit of the MGB housing and replacing any MGB housing that exceeds the life limit. Since issuance of the NPRM, the FAA has determined that the affected MGB housings are no longer in service. Accordingly, the NPRM is withdrawn.

DATES:

The FAA is withdrawing the proposed rule published July 21, 2010 (75 FR 42340), as of March 15, 2021.

ADDRESSES:

Examining the AD Docket

You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2010-0720; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD action, any comments received, and other information. The street address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT:

Michael Schwetz, Aerospace Engineer, Aviation Safety Section, Boston ACO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Discussion

The FAA has issued an NPRM that proposed to amend 14 CFR part 39 by adding an AD that would apply to the specified products. The NPRM was published in the Federal Register on July 21, 2010 (75 FR 42340). The NPRM was prompted by a fatigue analysis conducted after a helicopter was found with a severed foot pad that failed due to fatigue.

The NPRM proposed to require revising the existing airworthiness limitations section of the ICA for your helicopter to reduce the life limit of the MGB housing and replacing any MGB housing that exceeds the life limit. The proposed actions were intended to address failure of the foot pad, loss of the MGB, and subsequent loss of control of the helicopter.

Actions Since the NPRM Was Issued

Since issuance of the NPRM, the FAA has determined that the affected MGB housings are no longer in service and the identified unsafe condition no longer exists. Therefore, the FAA has determined that AD action is not appropriate.

Withdrawal of the NPRM constitutes only such action and does not preclude the FAA from further rulemaking on this issue, nor does it commit the FAA to any course of action in the future.

Comments

The FAA gave the public the opportunity to comment on the NPRM. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Clarify Certain Language in the NPRM

Sikorsky Aircraft requested that the FAA clarify certain language in the NPRM.

The FAA acknowledges that, in the event of publication of a final rule, Sikorsky Aircraft's request would have been valuable in clarifying the language. However, this NPRM will not be published as a final rule. The FAA has determined that the affected MGB housings are no longer in service, and that the NPRM is no longer necessary.

FAA's Conclusions

Upon further consideration, the FAA has determined that the NPRM is unnecessary. Accordingly, the NPRM is withdrawn.

Regulatory Findings

Since this action only withdraws an NPRM, it is neither a proposed nor a final rule. This action therefore is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979).

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Withdrawal

Accordingly, the notice of proposed rulemaking, Docket No. FAA-2010-0720, which was published in the Federal Register on July 21, 2010 (75 FR 42340), is withdrawn.

Issued on January 25, 2021.

Lance T. Gant,

Director, Compliance & Airworthiness Division, Aircraft Certification Service.