A Hawker 900XP crew recently discovered after landing that a slightly out-of-tolerance closing mechanism can render the cabin door unopenable from inside the airplane, leaving the emergency hatch the only exit. The pilot radioed a lineman to grab the keys through the pilot’s side window and unlock the door handle from outside. After some investigation, the Hawker technician found that the receptacle in the door latch mechanism has a critical tolerance, and this Hawker’s receptacle needed adjustment. “It’s a relatively easy fix, just a matter of putting [two] washers under the receptacle,” the pilot told AIN. He also found that when the mechanism is out of tolerance the locked door handle can be forced from outside to open the door. Hawker Beechcraft is investigating this problem.