Summary
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 707 airplanes. This proposed AD was prompted by analysis of the cam support assemblies of the main cargo door that indicated the repetitive high frequency eddy current (HFEC) inspections required by the existing maintenance program are not adequate to detect cracks before two adjacent cam support assemblies of the main cargo door could fail. This proposed AD would require repetitive ultrasonic inspections for cracking of the cam support assemblies of the main cargo door and replacement if necessary. We are proposing this AD to detect and correct cracking of the cam support assemblies of the main cargo door. Such cracking could result in reduced structural integrity of the main cargo door and consequent rapid decompression of the airplane.