AD 2023-22-17 Airworthiness Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier Inc. and de Havilland, Inc.) Airplanes

Models named: DHC-3. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Viking Air Limited (type certificate previously held by Bombardier Inc. and de Havilland, Inc.) Model DHC-3 airplanes, all serial numbers, certificated in any category.

Comply with this AD within the compliance times specified, unless already done.

(1) Within 6 months after the effective date of this AD, do a detailed visual inspection of the lower engine mount pickup fittings part numbers (P/Ns) C3FS46-7 and C3FS46-8 and the upper engine mount pickup fittings P/Ns C3FS42-5 and C3FS42-6 for cracking, deformation (altered form or shape), corrosion, fretting or wear, paint or surface coating damage (loose, delaminating, flaking, peeling, chipping of the coating or paint, exposed bare metal, or corroded), and loose, missing, or broken fasteners, in accordance with Part A, steps 1 through 8, of the Accomplishment Instructions in Viking Service Bulletin V3/0012, Revision NC, dated January 20, 2022 (Viking SB V3/0012). (2) If any crack or deformation (altered form or shape) of any engine mount pickup fitting is found during the detailed visual inspection required by paragraph (g)(1) of this AD, before further flight, replace the fitting with a new or serviceable part, in accordance with Part A, step 10, of the Accomplishment Instructions in Viking SB V3/0012. For purposes of this AD, “new” means zero hours time-in-service. (3) If any paint or surface coating of the engine mount pickup fitting is found damaged (loose, delaminating, flaking, peeling, chipping of the coating or paint, exposed bare metal, or corroded) during the detailed visual inspection required by paragraph (g)(1) of this AD, before further flight, repair the fitting in accordance with Part 1 of Viking PSM 1-3-5, DHC-3 Otter Supplemental Inspection and Corrosion Control Manual, Revision IR, dated December 21, 2017 (Viking PSM 1-3-5, Revision IR), and Part A, step 12, of the Accomplishment Instructions in Viking SB V3/0012. Where Part 1 of Viking PSM 1-3-5, Revision IR, specifies contacting Viking if the alloy and condition of an affected engine mount pickup fitting cannot be identified, this AD requires contacting the Manager, International Validation Branch, FAA; Transport Canada; or Viking's Transport Canada Design Approval Organization (DAO) for instructions. (4) If any loose, missing, or broken fastener is found during the detailed visual inspection required by paragraph (g)(1) of this AD, before further flight, replace the fastener with a new fastener, do a detailed visual inspection of the fastener hole to detect cracking, corrosion, an elongated bore hole, bore surface roughness, or other defects (abnormalities when compared to a new part), and repair any damage found or replace the engine mount pickup fitting with a new or serviceable part if damage is beyond repairable limits, in accordance with Part 1 of Viking PSM 1-3-3 DHC-3 Otter Repair Manual, dated August 1, 1963, and Part A, step 9, of the Accomplishment Instructions in Viking SB V3/0012. (5) If any corrosion, wear, or fretting to any engine mount pickup fitting is found during the detailed visual inspection required by paragraph (g)(1) of this AD, before further flight, contact the Manager, International Validation Branch, FAA; Transport Canada; or Viking's Transport Canada DAO to obtain instructions for an approved repair and, within the compliance timeframe specified therein, do the repair. If approved by the DAO, the approval must include the DAO-authorized signature. Alternatively, before further flight, replace the engine mount pickup fitting with a new or serviceable part in accordance with Part A, step 10, of the Accomplishment Instructions in Viking SB V3/0012.

This AD was prompted by a report of cracking in the left-hand side (LHS) and right-hand side (RHS) lower engine mount pickup fittings. The FAA is issuing this AD to address cracking in the LHS and RHS lower engine mount pickup fittings. The unsafe condition, if not addressed, could, in the case of cracking of any of the engine mount pickup fittings, result in failure of the fitting, leading to a loose connection of the engine mount ring, which provides main support for the engine at the firewall, and consequent reduced control of the airplane.

None.