Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Short Brothers Model SD3 series airplanes. This proposal would require repetitive tests (checks) of the power lever movement of the fuel control unit (FCU) lever to ensure the lever is contacting the maximum stop, adjustment of the FCU rigging, if necessary; and an engine ground run for correct gas generator rotational speed. This proposal also would require a static reduced power check on each engine to ensure correct operation of the reserve takeoff power (RTOP) system; and follow-on actions, if necessary. This action is necessary to prevent failure of the engines to reach adequate RTOP boost during takeoff, which could result in reduced controllability of the airplane. This action is intended to address the identified unsafe condition.