Summary
We propose to adopt a new airworthiness directive (AD) for certain Beechcraft Corporation (Type Certificate Previously Held by Hawker Beechcraft Corporation; Raytheon Aircraft Company; Beech Aircraft Corporation) Model 400, 400A, 400T, and MU-300 airplanes. This proposed AD was prompted by a report of a failure of the Acme nut threads in a pitch trim actuator (PTA). This proposed AD would require an inspection to determine if PTAs having a certain serial number and part number are installed, and replacement if they are installed. This proposed AD would also require repetitive replacements of PTAs with new PTAs or certain overhauled PTAs. We are proposing this AD to prevent failure of the Acme nut threads in the PTA, which could lead to loss of control of pitch trim and reduced controllability of the airplane.