Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 757 airplanes. This proposed AD was prompted by reports of single and multiple uncommanded spoiler panel extensions during flight when there was a hydraulic system failure. This proposed AD would require replacing certain spoiler power control units (PCUs) with new or changed PCUs. We are proposing this AD to prevent an uncommanded extension of spoiler panels in the event of a hydraulic system failure, which could result in loss of control of the airplane.