DHC 8 Q400 series nose landing gear door spring - Service Difficulty Advisory

No. AV-2008-01
2008 01 17

On final approach for landing, the crew was unable to extend the nose landing gear (NLG).  To further compound this in-flight problem, activation of the alternate (emergency) landing gear extension was also unsuccessful.  An emergency landing was carried out with the nose landing gear retracted.

Preliminary investigation revealed that the forward nose gear door extension spring (P/N 47844-1) had broken at the door attachment point and jammed between the lower drag strut and the resident hydraulic lines.  This situation prevented the NLG from extending using either the normal or alternate extension system.  Please refer to Manufacturers Illustrated Parts Catalog (IPC) 32-31-61, pages 1–3 for the NLG Door Mechanism pictorials.

An SDR search and consultation with Bombardier revealed two previous reports of a broken spring but without any secondary events.  However, a foreign airworthiness authority has recently informed Transport Canada Civil Aviation (TCCA) that their domestic operator has found that 10 of the 13 NLG door springs showed defects in accordance with the inspection requirements detailed in Bombardier (BA) All Operator Message (AOM) 249.

Bombardier has issued Reference Instruction Letter (RIL) RIL-84-32-060 titled “Spring Replacement – NLG Door Mechanism” dated 24 September 2007, which was addressed to all Q400 operators.

TCCA is currently investigating with the foreign investigative authority and BA to determine the root cause of the door spring failure and will introduce appropriate corrective action, as necessary.

In the interim, TCCA hereby advise all operators, maintainers and other interested persons to comply with the visual and liquid penetrant inspection (LPI) requirements contained in the Goodrich Service Concession Request (SCR) 101-07 of the aforementioned BA AOM 249.

Defects, malfunctions and failures occurring on aeronautical products should be reported to TCCA, Continuing Airworthiness, in accordance with CAR 591 mandatory reporting requirements.

For further information, please contact a Transport Canada Centre, or Mr. Barry Caldwell, Continuing Airworthiness, Ottawa, telephone 613-952-4358 or caldweb@tc.gc.ca

For Director, National Aircraft Certification

B. Goyaniuk
Chief, Continuing Airworthiness

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