[Federal Register Volume 86, Number 36 (Thursday, February 25, 2021)]
[Proposed Rules]
[Pages 11476-11477]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03655]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21679; Directorate Identifier 2004-SW-33-AD]
RIN 2120-AA64


Airworthiness Directives; Robinson Helicopter Company Model R22 
Series Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Proposed rule; withdrawal.

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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 Robinson Helicopter Company (RHC) Model R22 series 
helicopters. The NPRM was prompted by an in-flight break up of a 
helicopter on which both teeter stop brackets (brackets) failed. The 
NPRM would have required replacing each main rotor blade (blade) droop 
and teeter stop (stop) and bracket and associated hardware with 
redesigned and improved airworthy parts. Since issuance of the NPRM, 
the FAA has determined that failure of the brackets was caused by 
turbulence and other factors that are addressed in AD 95-26-04. 
Accordingly, the NPRM is withdrawn.

DATES: The FAA is withdrawing the proposed rule published June 28, 2005 
(70 FR 37059), as of February 25, 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-2005-
21679; 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: James Guo, Aviation Safety Engineer, 
Los Angeles ACO Branch, FAA, 3960 Paramount Blvd., Lakewood, California 
90712; telephone 562-627-5357; email <a href="/cdn-cgi/l/email-protection#4e242f232b3d60293b210e282f2f60292138"><span class="__cf_email__" data-cfemail="553f343830267b32203a153334347b323a23">[email protected]</span></a>.

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 June 28, 2005 (70 FR 37059). The 
NPRM was prompted by an accident that involved an in-flight breakup of 
a helicopter that had old part-numbered stops and brackets installed. 
While the probable cause of the in-flight breakup had not been 
determined, the FAA believed failure of the stops or brackets may have 
been a contributing factor. Accordingly, the NPRM proposed to require 
replacing the stops and brackets with redesigned, airworthy parts. The 
proposed actions were intended to prevent failure of the stops and 
brackets, blade contact with the airframe, 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 unsafe 
condition was caused by different factors than those stated in the 
NPRM. Previously, RHC had introduced service information to replace the 
stops and brackets that were the subject of the NPRM with redesigned 
parts. The redesign introduced a material change from aluminum to 
stainless steel. However, the redesigned parts were mistakenly 
evaluated as a change that would address the unsafe condition. It has 
since been determined that the strength increase in the redesign is 
insignificant and would not have improved the outcome of the accident. 
It has also been determined that the accident was caused by mast 
bumping, which is addressed in AD 95-26-04 (60 FR 66487, December 22, 
1995) (AD 95-26-04). Therefore, the FAA has determined that AD action 
is not required and the NPRM is withdrawn.
    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.

Requests

    One commenter stated that the stops and droops could not have 
contributed to the accident as contact with those items occurs only 
when operating a Model R22 helicopter outside of its certificated 
flight envelope, accordingly making it an operational issue. The 
commenter requested the FAA table the proposed AD until the accident 
investigation is complete.
    The FAA acknowledges the commenter's request. The FAA further 
determined that the unsafe condition was caused by mast bumping, which 
is addressed in AD 95-26-04. Because the FAA is withdrawing the NPRM 
and has issued AD 95-26-04, the commenter's request is no longer 
necessary.
    A second commenter requested that the proposed action be modified 
by inclusion of the following or similar statement: ``The requirement 
to install certain part-numbered specific parts shall be interpreted 
broadly to include any replacements parts approved under FAR 21.303 for 
the original equipment parts cited in this action. Nothing in this 
action prevents or precludes the installation of such alternatively 
approved parts.''
    The FAA acknowledges the commenter's request. However, because the 
FAA is withdrawing the NPRM, the commenter's request is no longer 
necessary.

FAA's Conclusions

    Upon further consideration of the available information, 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

[[Page 11477]]

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

0
Accordingly, the notice of proposed rulemaking, Docket No. FAA-2005-
21679, Directorate Identifier 2004-SW-33-AD, which was published in the 
Federal Register on June 28, 2005 (70 FR 37059), is withdrawn.

    Issued on February 4, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-03655 Filed 2-24-21; 8:45 am]
BILLING CODE 4910-13-P


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