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Federal Register / Vol. 86, No. 146 / Tuesday, August 3, 2021 / Proposed Rules Aziz Ahmed, Aerospace Engineer, Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 5162287329; fax 516794
5531; email 9-avs-nyaco-cos@faa.gov.
SUPPLEMENTARY INFORMATION:
FOR FURTHER INFORMATION CONTACT:

Comments Invited The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under ADDRESSES. Include Docket No.
FAA20210613; Project Identifier MCAI202001431T at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend the proposal because of those comments.
Except for Confidential Business Information CBI as described in the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to https
www.regulations.gov, including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
Confidential Business Information CBI is commercial or financial information that is both customarily and actually treated as private by its owner.
Under the Freedom of Information Act FOIA 5 U.S.C. 552, CBI is exempt from public disclosure. If your comments responsive to this NPRM
contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important
that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI
as PROPIN. The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI
should be sent to Aziz Ahmed, Aerospace Engineer, Airframe and Propulsion Section, FAA, New York ACO Branch, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590;
telephone 5162287329; fax 516794
5531; email 9-avs-nyaco-cos@faa.gov.
Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
Background Transport Canada Civil Aviation TCCA, which is the aviation authority for Canada, has issued TCCA AD CF
202043, dated October 21, 2020
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
8400, 401, and 402 airplanes. You may examine the MCAI in the AD
docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210613.
This proposed AD was prompted by a report of cracking found on an MLG
drag strut assembly. The MLG drag strut had accumulated a total of 26,968 flight cycles and 12,392 flight hours since new, of which 2,830 flight cycles and 1,420 flight hours had accumulated since the last overhaul. The last overhaul had been conducted one year prior to the crack finding. It is suspected that the cracking was caused by the clamping method used by the repair facility during the most recent overhaul, and was missed during subsequent non-

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destructive testing NDT inspections required as part of the refurbishment process. The FAA is proposing this AD
to address cracking of the MLG drag strut assembly and possible failure under compression loads during landing or ground operations, which could result in asymmetric MLG configuration and potential runway excursion. See the MCAI for additional background information.
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 proposing this AD because the FAA
evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop on other products of the same type design.
Proposed AD Requirements in This NPRM
This proposed AD would require a records review to determine if an affected MLG drag strut assembly is installed, repetitive detailed inspections for cracking of affected strut assemblies, a one-time magnetic particle inspection for cracking, and on-condition actions if necessary. On-condition actions include replacing the MLG drag strut assembly and re-identifying the MLG drag strut assembly.
Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 34
airplanes of U.S. registry. The FAA
estimates the following costs to comply with this proposed AD:

ESTIMATED COSTS FOR REQUIRED ACTIONS
Labor cost
Parts cost
Cost per product
Up to 11 work-hours $85 per hour = Up to $935

$0

Up to $935

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The FAA estimates the following costs to do any necessary on-condition actions that would be required based on
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the results of any required actions. The FAA has no way of determining the
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Cost on U.S.
operators Up to $31,790.

number of aircraft that might need these on-condition actions:

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