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Federal Register / Vol. 86, No. 242 / Tuesday, December 21, 2021 / Rules and Regulations Federal eRulemaking Portal: Go to https www.regulations.gov. Follow the instructions for submitting comments.
Fax: 2024932251.
Mail: U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5
p.m., Monday through Friday, except Federal holidays.
For service information identified in this final rule, contact De Havilland Aircraft of Canada Limited, Q-Series Technical Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone 4163754000; fax 4163754539; email thd@
dehavilland.com; internet https
dehavilland.com. You may view this referenced service information at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 2062313195.
It is also available on the internet at https www.regulations.gov by searching for and locating Docket No.
FAA20211064.
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. FAA2021
1064; or in person at the Docket Management Facility between 9 a.m.
and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, any comments received, and other information. The street address for the Docket Operations office is listed above. Comments will be available in the AD docket shortly after receipt.
FOR FURTHER INFORMATION CONTACT:
Antariksh Shetty, Aerospace Engineer, Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY
11590; telephone 5162287300; fax 5167945531; email 9-avs-nyaco-cos@
faa.gov.

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SUPPLEMENTARY INFORMATION:

Discussion The FAA issued AD 20171909, Amendment 3919039 82 FR 43829, September 20, 2017 AD 20171909, which applied to certain De Havilland Aircraft of Canada Limited Type Certificate Previously Held by
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Bombardier, Inc. Model DHC8400, 401, and 402 airplanes. AD 201719
09 was prompted by reports of discrepancies of a certain bolt at the pivot pin link, resulting in corrosion of the bolt. AD 20171909 required modifying the NLG shock strut assembly. The FAA issued AD 2017
1909 to address failure of the pivot pin retention bolt, which could result in a loss of directional control or loss of an NLG tire during takeoff or landing.
Actions Since AD 20171909 Was Issued Since the FAA issued AD 201719
09, the FAA has determined new actions are necessary to address the unsafe condition. New bolts that have been installed must be repetitively lubricated and replaced before reaching their life limit. Failure of the pivot pin retention bolt could result in loss of directional control or loss of a NLG tire during takeoff or landing, which could lead to runway excursions. The actions required by AD 20171909 are not retained in this AD.
Transport Canada Civil Aviation TCCA, which is the aviation authority for Canada, has issued TCCA AD CF
200929R4, dated October 1, 2021
TCCA AD CF200929R4 also referred to after this as the Mandatory Continuing Airworthiness Information, or the MCAI, to correct an unsafe condition for certain De Havilland Aircraft of Canada Limited Model DHC
8401 and 402 airplanes. You may examine the MCAI in the AD docket on the internet at https
www.regulations.gov by searching for and locating Docket No. FAA2021
1064.
This AD was prompted by reports of a certain bolt at the pivot pin link being found missing or having stress corrosion cracking. The FAA is issuing this AD to address failure of the pivot pin retention bolt, which could result in a loss of directional control or loss of an NLG tire during takeoff or landing. See the MCAI
for additional background information.
Related Service Information Under 1
CFR Part 51
De Havilland Aircraft of Canada Limited has issued Service Bulletin 84
32167, dated August 12, 2021. This service information describes procedures for repetitive lubrications of the trailing arm of the NLG, which include a general visual inspection of the NLG pivot pin mechanism for discrepancies i.e., bolt part number P/N NAS60214D is missing or has damage e.g., stress corrosion or stress corrosion cracking and replacement of missing or damaged bolts.

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De Havilland Aircraft of Canada Limited has also issued Temporary Revision ALI0223, dated October 15, 2020. This service information describes new and revised airworthiness limitations, including life limits for certain bolts as specified in Structures Safe Life Task 322101701 and Task 322101702.
This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
FAAs Determination This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to the FAAs bilateral agreement with the State of Design Authority, the FAA has been notified of the unsafe condition described in the MCAI and service information referenced above. The FAA
is issuing this AD because the FAA
evaluated all pertinent information and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design.
Requirements of This AD
This AD requires accomplishing the actions described previously for De Havilland Aircraft of Canada Limited Service Bulletin 8432167, dated August 12, 2021. This AD also requires revising the existing maintenance or inspection program to include new and revised airworthiness limitations life limits for certain bolts.
Differences Between This AD and the MCAI or Service Information Part I of TCCA AD CF200929R4
requires a modification to the NLG
shock strut assembly within 1,600 flight cycles or 9 months for certain airplanes.
The FAA is currently considering requiring the modification in order to address the identified unsafe condition.
However, the planned compliance time for the installation of the modification would allow enough time to provide notice and opportunity for prior public comment on the merits of the modification. Therefore, this AD does not include the modification.
Part III of TCCA AD CF 200929R4
applies to all airplanes but specifies to do the actions using De Havilland Aircraft of Canada Service Bulletin 84
32167, dated August 12, 2021. The service information only has instructions for pivot pin retention bolt P/N NAS620414D. Therefore, the repetitive lubrications specified in i of this AD is for airplanes with pivot pin
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