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Federal Register / Vol. 86, No. 36 / Thursday, February 25, 2021 / Proposed Rules
k Related Information 1 For more information about this AD, contact Michael Schwetz, Aviation Safety Engineer, Boston ACO Branch, FAA, 1200
District Avenue, Burlington, MA 01803;
phone: 781 2387761; fax: 781 2387199;
email: michael.schwetz@faa.gov.
2 For service information identified in this AD, contact Hamilton Sundstrand, 1
Hamilton Road, Windsor Locks, CT 06096
1010; phone: 877 8087575; email: CRC@
collins.com. You may view this referenced service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 1200 District Avenue, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781 2387759.
Issued on February 8, 2021.
Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service.
FR Doc. 202103607 Filed 22421; 8:45 am BILLING CODE 491013P

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration 14 CFR Part 39
Docket No. FAA200521679; Directorate Identifier 2004SW33AD
RIN 2120AA64

Airworthiness Directives; Robinson Helicopter Company Model R22 Series Helicopters Federal Aviation Administration FAA, DOT.
ACTION: Proposed rule; withdrawal.
AGENCY:

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 9526
04. Accordingly, the NPRM is withdrawn.

SUMMARY:

The FAA is withdrawing the proposed rule published June 28, 2005
70 FR 37059, as of February 25, 2021.
ADDRESSES:
DATES:

VerDate Sep<11>2014

16:43 Feb 24, 2021

Jkt 253001

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. FAA2005
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 W12140, 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 5626275357; email james.guo@faa.gov.
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,
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which is addressed in AD 952604 60
FR 66487, December 22, 1995 AD 95
2604. 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 FAAs 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 commenters request. The FAA further determined that the unsafe condition was caused by mast bumping, which is addressed in AD 952604. Because the FAA is withdrawing the NPRM and has issued AD 952604, the commenters 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 commenters request. However, because the FAA is withdrawing the NPRM, the commenters request is no longer necessary.
FAAs 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

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