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Federal Register / Vol. 86, No. 241 / Monday, December 20, 2021 / Rules and Regulations
2 Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/
certificate holding district office.

DEPARTMENT OF TRANSPORTATION

l Related Information
Docket No. FAA20210951; Project Identifier AD202101047R; Amendment 3921804; AD 20212306

For more information about this AD, contact Hal Jensen, Aerospace Engineer, Operational Safety Branch, Compliance &
Airworthiness Division, FAA, 950 LEnfant Plaza N SW, Washington, DC 20024;
telephone 202 2679167; email hal.jensen@
faa.gov.
1 The Director of the Federal Register approved the incorporation by reference of the service information listed in this paragraph under 5 U.S.C. 552a and 1 CFR
part 51.
2 You must use this service information as applicable to do the actions required by this AD, unless this AD specifies otherwise.
i European Union Aviation Safety Agency EASA AD 20210065, dated March 8, 2021.
ii Reserved 3 For EASA AD 20210065, contact EASA, Konrad-Adenauer-Ufer 3, 50668
Cologne, Germany; telephone +49 221 8999
000; email ADs@easa.europa.eu; internet www.easa.europa.eu. You may find the EASA material on the EASA website at https ad.easa.europa.eu.
4 You may view this service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N321, Fort Worth, TX 76177. For information on the availability of this material at the FAA, call 817 2225110.
This material may be found in the AD docket at https www.regulations.gov by searching for and locating Docket No. FAA20210834.
5 You may view this material that is incorporated by reference at the National Archives and Records Administration NARA. For information on the availability of this material at NARA, email fr.inspection@nara.gov, or go to: https
www.archives.gov/federal-register/cfr/ibrlocations.html.

FR Doc. 202127390 Filed 121721; 8:45 am
khammond on DSKJM1Z7X2PROD with RULES

BILLING CODE 491013P

14 CFR Part 39

RIN 2120AA64

Airworthiness Directives; Various Model 234 and Model CH47D
Helicopters Federal Aviation Administration FAA, DOT.
ACTION: Final rule; request for comments.
AGENCY:

m Material Incorporated by Reference
Issued on November 23, 2021.
Lance T. Gant, Director, Compliance & Airworthiness Division, Aircraft Certification Service.

Federal Aviation Administration
The FAA is adopting a new airworthiness directive AD for various Model 234 and Model CH47D
helicopters. This AD was prompted by two reports of mechanical failures of the longitudinal cyclic trim actuator LCTA. This AD requires determining the maintenance history, and hours time-in-service TIS and number of lift cycles for each LCTA since last overhaul, and then requires initial and repetitive overhauls of each LCTA based on that maintenance and service history.
This AD also prohibits installing an LCTA unless it meets certain requirements. Finally, this AD requires reporting certain information to the FAA. The FAA is issuing this AD to address the unsafe condition on these products.

SUMMARY:

This AD is effective January 4, 2022.
The FAA must receive comments on this AD by February 3, 2022.
ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https www.regulations.gov. Follow the instructions for submitting comments.
Fax: 202 4932251.
Mail: U.S. Department of Transportation, Docket Operations, M30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
DATES:

Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210951; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal
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holidays. The AD docket contains this final rule, any comments received, and other information. The street address for the Docket Operations is listed above.
FOR FURTHER INFORMATION CONTACT:
David Herron, Aerospace Engineer, Systems & Equipment Section, Seattle ACO Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206 2313554; email david.herron@faa.gov.
SUPPLEMENTARY INFORMATION:
Background The FAA received two reports of mechanical failure of an LCTA, the function of which is to constrain and control the non-rotating swashplate. In both failures, which occurred on Model CH47D helicopters, the flight crew was forced to make an emergency landing as they had difficulty controlling the helicopter. Model 234 and Model CH
47D helicopters both have the same LCTA installed, with two installed on each rotorcraft. Investigation as to the root cause of these failures has determined that inadequate maintenance overhaul procedures and scheduled overhaul intervals for this critical flight component with a single structural load path likely contributed to this unsafe condition. One event occurred due to excessive wear of the acme screw threads from degradation or lack of lubrication. The other event was due to metal fatigue leading to the fracture of the fourth stage spur gear shaft part of the acme screw caused by repetitive abnormal loading. The repetitive abnormal loading occurred because of the incorrect installation of a travel limit switch, which rendered the switch ineffective in removing power from the electric motor at the designed travel limit, thus allowing the electric motor to repetitively overstroke the actuator into a mechanical stop. While the failure modes were different, the failure effects were the same: Loss of the constraint and control normally provided by the LCTA. Failure of the LCTA, if not prevented, could result in loss of control of the rotor blades and subsequent loss of control of the helicopter or the rotor blades striking the fuselage. The FAA is issuing this AD
to address the unsafe condition on these products.
The type certificate TC holder for Model 234 helicopters is Columbia Helicopters Inc. TC previously held by Boeing Defense & Space Group, and the TC holders for Model CH47D
helicopters currently include Columbia Helicopters, Inc., Billings Flying Service, Inc., Tandem Rotor, LLC, and Unical Aviation, Inc. originally
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