In part. I've altered some of the formatting to make it easier to read and snipped out some parts:
DATE: October 4, 2022
AD #: 2022-21-51
Emergency Airworthiness Directive (AD) 2022-21-51 is sent to owners and operators of
Viking Air Limited (type certificate previously held by Bombardier Inc. and de Havilland, Inc.)
Model DHC-3 airplanes.
Background
This Emergency AD was prompted by multiple recent reports of cracks in the left -hand
elevator auxiliary spar. The FAA’s analysis of these reports indicates that immediate AD action is warranted. The FAA is issuing this AD to detect and address cracks, corrosion, and previous repairs to the left-hand elevator auxiliary spar. The unsafe condition, if not addressed, could result in elevator flutter leading to elevator failure, with consequent loss of control of the airplane.
The FAA has coordinated this issue with Transport Canada, which is the aviation authority for
Canada. Transport Canada issued AD CF-2018-04, dated January 19, 2018 (Transport Canada AD CF-2018-04), which includes a requirement for inspecting elevator assemblies for corrosion. The FAA issued a notice of proposed rulemaking that published in the Federal Register on February 8, 2022 (87 FR 7059) in response to Transport Canada AD CF-2018-04, and is currently addressing comments.
As an interim action, the FAA is issuing this Emergency AD, as a result of the recent reports, to mandate an inspection of the left-hand elevator auxiliary spar and replacement if necessary.
FAA’s Determination
The FAA is issuing this AD because the agency has determined that an unsafe condition is
likely to exist or develop in other products of the same type design.
AD Requirements
This AD requires repetitive detailed visual inspections of the entire left-hand elevator
auxiliary spar for cracks, corrosion, and previous repairs, and depending on the findings, replacement of the left-hand elevator auxiliary spar. This AD also requires sending the inspection results to the FAA.
Interim Action
The FAA considers this AD to be an interim action. If final action is later identified, the FAA might consider further rulemaking.
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The FAA is issuing this AD under 49 U.S.C. Section 44701 according to the authority
delegated to me by the Administrator.
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(d) Subject
Joint Aircraft System Component (JASC) Code 5520, Elevator Structure.
(e) Unsafe Condition
This AD was prompted by multiple recent reports of cracks in the left-hand elevator auxiliary spar. The FAA’s analysis of these reports indicates that immediate AD action is warranted. The FAA is issuing this AD to detect and address cracks, corrosion, and previous repairs to the left-hand elevator auxiliary spar. The unsafe condition, if not addressed, could result in elevator flutter leading to elevator failure, with consequent loss of control of the airplane.
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(h) Inspection
(1) Within 10 hours time in service (TIS) or 3 days after receipt of this Emergency AD,
whichever occurs first, unless already done within the last 90 days, and thereafter at intervals not to exceed 110 hours TIS, remove the left-hand elevator tab from the elevator and perform a detailed visual inspection of the entire left-hand elevator auxiliary spar for cracks, corrosion, and previous repairs. For the purposes of this AD, structural reinforcements are not considered previous repairs.
(2) If any crack, corrosion beyond Level 1, or previous repair is found during any inspection required by this Emergency AD, before further flight, replace the left -hand elevator auxiliary spar.
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(k) Related Information
For further information about this AD, contact: James Delisio, Continued Operational Safety Program Manager, COS Program Management Section, Operational Safety Branch, FAA, 1600 Stewart Avenue, Westbury, NY 11590; phone: (516) 228-7300; email:
9-avs-nyaco-cos@faa.gov.
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