Summary
This document proposes adopting a new airworthiness directive (AD) for certain serial numbered MD Helicopters, Inc. (MDHI) Model MD900 helicopters. The AD would require, for the lateral-mixer bellcrank assembly (bellcrank), establishing a life limit, creating a component history card or equivalent record, determining the hours time-in-service (TIS), and applying a serial number (S/N). This proposal is prompted by additional testing, which revealed that the original load test to establish the life limits of the bellcrank did not accurately represent the actual loading. The actions specified by the proposed AD are intended to prevent fatigue failure of the bellcrank and subsequent loss of lateral control of the helicopter.