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:
Several operators have reported pitch oscillations and/or elevator asymmetry caution lights illumination when flying with the autopilot engaged. Investigations revealed that loose rivets in the torque tube assemblies caused relative motion between the crank arms and torque tubes.
Loose rivets could result in excessive wear and subsequent significant backlash in the driving crank arms. This condition, if left uncorrected, will progressively get worse and degrade the controllability of the aeroplane.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.