AD 2022-03-23 Requires Updating The Software Version Of The Yaw Servo

The FAA is adopting a new airworthiness directive (AD) for certain Textron Aviation Inc. (type certificate previously held by Raytheon Aircraft Company, Hawker Beechcraft Corporation, and Beechcraft Corporation) (Textron) Model 300, 300LW, B300, and B300C airplanes.

This AD was prompted by a report of a timing issue where the yaw servo software can generate a motor position fault when the pilot applies rudder input at the same time the rudder boost system is activated, which disables the rudder boost function and leads to a reduced ability of the flight crew to maintain the safe flight and landing of the airplane or loss of control of the airplane. This AD requires updating the software version of the yaw servo. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective February 22, 2022.

Supplementary Information: Garmin informed the FAA of a problem during flight testing with the Garmin International, Inc., G1000 integrated avionics system installed on Textron Model 300, 300LW, B300, and B300C airplanes in accordance with Supplemental Type Certificate (STC) No. SA01535WI-D. A timing issue in the yaw servo software can generate a motor position fault when the pilot applies rudder input at the same time the rudder boost system is activated, which disables the rudder boost function.

The rudder boost system applies additional rudder force, using the GSA 9000 yaw servo, following loss of an engine or significant loss of thrust, which limits the rudder force required to maintain directional control of the airplane. Loss of the rudder boost system without warning before the moment rudder boost is needed could result in the inability of the flight crew to maintain the safe flight and landing of the airplane or loss of control of the airplane. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov