Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
A failure mode has been identified following the examination of parts from another aircraft type (Jetstream 4100 series) that can lead to the loss of a nose-wheel. The Jetstream (HP.137) Mk1, 200, 3100 and 200 series use a similar method for retaining the wheel assemblies on the landing gear axle and can therefore experience the same type of failure, i.e. a combination of excessive wear and/or adverse tolerances on the axle inner cone, outer cone or wheel hub splined sleeve cones resulting in the loss of the critical gap between the inner flange face of the wheel outer cone and the axle end face. If this gap is lost, it results in the wheelhaving free play along the length of the axle. This condition, if not corrected, can cause the wheel nut lock plate to break, leading to the wheel retention nut unscrewing and subsequent separation of the nose wheel from the landing gear axle.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.