Airworthiness Directives; The Boeing Company Model 757-200 Series Airplanes Modified by Supplemental Type Certificate (STC) ST01529SE or STC ST02278SE

We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 757-200 series airplanes modified by particular STCs. This AD was prompted by reports of a main cargo door being blown past its full open position while on the ground during gusty wind conditions, which resulted in uncontrolled fall down to its closed position. This AD requires installing a new placard and bracket, replacing an existing placard, and replacing the main cargo door control panel. We are issuing this AD to prevent damage to the main cargo door, which could result in rapid decompression of the airplane, or injury to maintenance and ground crew during ground operations.