Summary
We propose to adopt a new airworthiness directive (AD) for certain ATR-GIE Avions de Transport R gional Model ATR42-500 and Model ATR72-102, -202, -212, and -212A airplanes. This proposed AD was prompted by reports of failure of emergency power supply units (EPSUs) in production and in service. This proposed AD would require an inspection to determine the part number and serial number of each EPSU, and replacement if necessary. We are proposing this AD to address the unsafe condition on these products.