Several cases involving the failure of Bombardier Q400 landing gear to retract after take-off have prompted US FAA officials to propose a new airworthiness directive (AD) for the turboprop.

The proposed AD would mandate incorporation of new weight-on-wheels (WOW) and steering harnesses that have a new conduit construction, says the FAA today in a notice of proposed rulemaking (NPRM).

It estimates that about 42 products of US registry will be affected, and that the cost to operators of implementing the AD will be $43,680 or $1,040 per unit.

The action described in the NPRM was previously addressed in a mandatory continuing airworthiness information (MCAI) document issued by Transport Canada after several cases were reported whereby the landing gear did not retract after take-off.

Subsequent investigation revealed this was caused by fatigue failure of the nose landing gear electrical harness. The MCAI noted that, in conjunction with one engine being inoperable, "this could, in certain operating conditions, affect continued safe flight and landing".

In its NPRM today, the FAA says it is proposing this AD "because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design".

Comments concerning the proposed AD must be submitted to the regulator by 10 November.

Source: Air Transport Intelligence news