What happened
On January 14, 2014, an Israel Aircraft Industries Gulfstream 200, registration N720QS, was performing a post-maintenance operational check flight when the auxiliary power unit (APU) service door opened in-flight. The aircraft departed Savannah/Hilton Head International Airport (SAV) at 1436 under visual meteorological conditions with a visibility of 10 statute miles and winds of 300 degrees at 14 knots.
As the aircraft climbed through 16,000 feet at 280 knots, the crew experienced a "thud" and a momentary shudder. No abnormal handling characteristics were noted for the remainder of the flight. Upon landing at SAV, the crew discovered that the APU service door was open and bent, though it remained attached at its aft hinge point. The lower latches were in the down and locked position, but the side latches were in the open position and appeared to be bent as if torn away. The lower portion of the rudder sustained substantial damage due to contact with the door. There were no injuries to the two pilots.
The investigation
The aircraft had recently undergone several rounds of maintenance to address a recurring landing gear position indication issue. Following a maintenance event on January 10, a fuel leak in the APU compartment had been repaired. While previous post-maintenance inspections included verifying the security of vents and access doors, the inspection performed prior to the accident flight only covered areas that had received recent maintenance.
Investigation of the latches on N720QS showed proper overlap between the latches and the doubler. The manufacturer had previously noted that in some G200 aircraft, latches might have been trimmed during manufacturing, potentially causing insufficient overlap, but this was not the case on the accident aircraft.
Findings
- The crew's preflight inspection did not include a detailed check of the APU service door because the door's location required a ladder for access, and the inspection was limited to a visual confirmation of its security.
- Maintenance personnel failed to ensure the APU service door was properly secured before the aircraft was returned to service.