EASA AD CF-2021-28
Landing Gear — Nose Wheel Steering Hydraulic Motor — Potential Jam Due to Wear
Summary
Canadian Airworthiness Directive CF-2021-28 addresses a potential jam in the nose wheel steering hydraulic motor due to wear on piston rod shoes in De Havilland Aircraft of Canada Limited model DHC-8-401 and DHC-8-402 aeroplanes, serial numbers 4001 and 4003 through 4622. The directive mandates re-identification or replacement of affected hydraulic motors to prevent loss of directional control during ground operations. It also prohibits installation of certain older hydraulic motor part numbers on these aircraft models.
What Changed
CF-2021-28 introduces mandatory re-identification or replacement of nose wheel steering hydraulic motors with part number RS1267-5 to correct a design issue causing motor jams. It also prohibits installation of older hydraulic motor part numbers RS1267-1, RS1267-1 MOD SB 32-13, RS1267-2, RS1267-2 MOD SB 32-13, and RS1267-3 on affected aircraft. This is a new regulation addressing an unsafe condition reported by operators.
Why It Matters
This directive is critical for aviation professionals as it prevents potential nose wheel steering hydraulic motor jams that could lead to runway excursions and loss of directional control during pushback or towing. Compliance ensures continued airworthiness and safety of the affected De Havilland DHC-8-400 series aircraft. Maintenance and compliance teams must track and implement the required actions to avoid operational disruptions and regulatory penalties.
What To Do
Operators must perform re-identification or replacement of the nose wheel steering hydraulic motor within 12,000 flight hours or 72 months from the effective date of August 19, 2021, following the instructions in De Havilland Service Bulletin 84-32-164. Additionally, installation of specified older hydraulic motor part numbers is prohibited from the effective date. Compliance with these actions is mandatory to maintain airworthiness.
AI-generated summary from official EASA source document. Always verify against the original.