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:
BAE Systems have received three reports of uncommanded flap extensions affecting different Jetstream 31 aeroplanes. In one instance, the aeroplane exceeded the airspeed limit allowed for the uncommanded flap configuration, resulting in damage to the wing trailing edge. Following investigation, it was considered that a loss of electrical signal to the "up'' solenoid of the flap selector valve had occurred and, combined with the normal internal leakage in the hydraulic system, resulted in hydraulic pressure being supplied to the "down'' side of the flap hydraulic jack. The loss of signal could have been intermittent, and the evidence strongly implicated oxide debris contamination of the flap selector switch contacts. This condition, if not corrected, could lead to further cases of damage to the aeroplane due to airspeed limit exceedance, possibly resulting in asymmetric flap deployment, which could lead to loss of control of the aeroplane.