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Service Difficulty Advisory

AV 2000-02
24 March 2000

Mitsubishi MU-2B

Gear-up Landing

A western operator recently submitted an SDR related to landing gear system failures, which resulted in a gear-up landing.

When the landing gear could not be extended normally the crew tried to perform an emergency manual extension. After about eight or ten cycles of the emergency extension handle, the handle became too stiff to move and the gear could not be lowered further. The crew were forced (after extensive consultation with ground maintenance personnel) to land the aircraft with the gear up.

After the aircraft was recovered, maintenance personnel found the roller (P/N220AS-03-130) was missing from the emergency extension handle. The missing roller allowed the inner handle to disengage from the emergency extension handle before the right forward gear door had released. Not realizing this, the crew attempted to extend the landing gear using the emergency extension handle. Once the right gear came into contact with the closed gear door, the gear system could not be extended further, requiring the crew to land with the gear up.

Schematic of an emergency gear down handle with zoomed section on the roller

The roller is attached to the gear handle with a clevis pin secured with a cotter pin. The submitter feels that these parts fell out because of a missing or damaged cotter pin. He subsequently checked the rest of his company's fleet of five aircraft and found one other aircraft missing a cotter pin, although the roller and clevis pin were still in place.

Transport Canada recommends that operators of these aircraft carry out an initial inspection of their landing gear emergency extension handles for missing or damaged rollers and attaching parts. Operators should also consider adding an inspection task to their approved maintenance schedules, detailing an inspection of this area.

For further information, contact a Transport Canada Centre, or Mr. Mark Stephenson, Continuing Airworthiness, Ottawa, telephone (613) 952-4363, facsimile (613) 996-9178 or e-mail stephma@tc.gc.ca.

For Director, National Aircraft Certification

B. Goyaniuk
Chief, Continuing Airworthiness