The FAA has issued a Special Airworthiness Information Bulletin for certain Beech King Air F90/100/200s and Beech 99s. It details recent failures of main landing gear actuator nut assemblies (part numbers GMD115-810029-17 and -23) built by General Machine-Diecron (GMD), of Griffin, Ga. The assembly isinstalled only in aircraft thathave electrical/mechanical mainlanding gear systems.

The GMD main landing gear actuator nuts are FAA PMA-authorized replacement parts for Raytheon part numbers 115-810029-17 and -23 installed in the right main landing gear. The assembly uses a threaded bronze nut that screws into a threaded steel tube to complete the actuator nut assembly. Failure of the actuator nut assembly occurs when the bronze insert partially, or completely, separates from the steel tube, resulting in premature activation of a microswitch that prevents the gear from traveling to the down-and-locked position.

The failure occurs only on the right main landing gear because the gear retraction cycle tends to unscrew the threaded nut insert from the actuator nut assembly.

GMD has issued an Alert Service Bulletin (GM-D-ASB 32-30-01/030305) that recommends replacement of these assemblies as soon as practical, but not to exceed 10 days or 20 flight cycles.

A mandatory Raytheon Service Bulletin (SB No. 32-3433), dated August 2002 (Revision 1), was issued to require replacement of certain actuator nut assemblies listed therein due to separation of these actuator nut assemblies in the brazed insert area.

The FAA “strongly recommends” operators determine if either of the GMD actuator nut assemblies has been installed in the above Raytheon MLG actuator. If so, the operator should replace the GMD actuator nut assembly with a new part.

For information, visit www.faa. gov/aircraft/safety/alerts.