AD 2020-23-13 Prompted By False Activation Of The Stall Warning System

The FAA is adopting a new airworthiness directive (AD) for all ATR-GIE Avions de Transport Regional Airplanes Model ATR42-200, -300, and -320 airplanes. This AD was prompted by false activation of the stall warning system due to wiring damage on the wire bundle between an angle of attack (AOA) probe and the crew alerting computer.

This AD requires a one-time inspection for discrepancies of the wire bundles between the left- and right-hand AOA probes and the crew alerting computer, and, depending on findings, applicable corrective actions, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products. This AD becomes effective December 3, 2020.

Supplementary Information: The EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2020-0221, dated October 13, 2020 (EASA AD 2020-0221) (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for all ATR¡VGIE Avions de Transport Regional Airplanes Model ATR42-200, -300, and -320 airplanes.

This AD was prompted by false activation of the stall warning system due to wiring damage on the wire bundle between an AOA probe and the crew alerting computer. Such activation can lead to one or a combination of the following events:

• Autopilot disconnection;
• Stick pusher activation;
• Stick shaker activation;
• Aural stall warning (cricket audio alert);
• Master CAUTION light flashing amber;
• STICK PUSHER green light ON;
• FLT CTL amber light on CAP;
• Stick PUSHER/SHAKER pushbutton ‘FAULT' amber light illumination;
• Whooler Audio alert.

The FAA is issuing this AD to address this condition, which could result in loss of control of the airplane during take-off and landing phases. See the MCAI for additional background information.

FMI: www.regulations.gov