EASA AD CF-2021-08
Fuel System — Fuel Terminal — High Level Sensor Terminal Screw in Contact with Access Panel
Summary
The Canadian Airworthiness Directive CF-2021-08 addresses a fuel system issue on De Havilland Aircraft of Canada Limited model DHC-8-401 and -402 aeroplanes, serial numbers 4001 and 4003 through 4628. It identifies a potential contact between the #2 top high level sensor terminal screw and the #6 outer wing fuel access panel stiffener flange that could cause arcing during lightning strikes. This directive mandates corrective actions to eliminate this interference and prevent ignition risks inside the fuel tank.
What Changed
CF-2021-08 introduces mandatory removal and replacement or rework of the #6 outer wing fuel access panel assembly to prevent contact with the high level sensor terminal screw. It also prohibits installation of certain affected access panel part numbers on the specified DHC-8 models. This is a new regulation addressing a specific fuel system safety concern.
Why It Matters
This directive is critical for aviation professionals because it mitigates a potential ignition source inside the fuel tank caused by electrical arcing during lightning strikes. Operators and maintenance organizations must ensure compliance to maintain aircraft airworthiness and safety. Failure to comply could lead to unsafe operating conditions and regulatory violations.
What To Do
Affected operators must remove and replace or rework the #6 outer wing fuel access panel assembly within 8000 flight hours from the effective date of March 23, 2021, following the specified De Havilland Service Bulletin instructions. Additionally, installation of access panels with part numbers 85714233-003/-004 and 85714233-005/-006 is prohibited from the effective date onward.
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