NTSB Factual Report

On January 14, 2014, approximately 1447 eastern standard time, an Israel Aircraft Industries Gulfstream 200, N720QS, operated by NetJets Aviation, Inc., was substantially damaged when the auxiliary power unit (APU) service door opened in-flight near Savannah, Georgia. Both airline transport pilots were not injured. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the local flight, which departed Savannah/Hilton Head International Airport (SAV) at 1436. The post-maintenance operational check flight (OCF) was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.

The airplane had been undergoing general maintenance, as well as maintenance for a recurring landing gear position indication issue. The airplane was returned to service on January 9, 2014, and during the subsequent OCF, the crew discovered that the landing gear position indication issue had not been resolved. Additional maintenance was performed, and during the return-to-service inspection on January 10, a large quantity of fuel was noted in the APU compartment due to a leak in a fuel line fitting to the APU fuel control unit. An o-ring was removed and replaced at the location of the leak, and a subsequent leak test revealed no anomalies. The airplane was returned to service, and a second OCF revealed that the landing gear indication issue remained unresolved. The airplane underwent further maintenance from January 10 to January 14, and was returned to service on January 14.

Prior to departure on the accident flight, the crew performed a preflight inspection and observed no anomalies. They described the takeoff as normal, and stated that as the airplane climbed through 16,000 feet at 280 knots, they experienced a "thud" and momentary shudder. No other anomalies were observed, and the crew did not experience any abnormal handling characteristics with the airplane. Upon landing at SAV, the crew observed that the APU service door was open and bent, but remained attached at its aft hinge point. The door's lower latches were in the down and locked position, and the side latches were in the open position. The crew noted that the side latches were "bent as if torn away." The lower portion of the rudder exhibited substantial damage due to contact with the door. According to the operator, the crew's preflight inspection included only a visual confirmation of the security of the service door, because due to its location on the airplane, the door could only be accessed with the aid of a ladder.

Review of work orders indicated that prior to each OCF on January 9 and 10, the airplane received a full post-maintenance inspection, which included verifying aft fuselage accesses, antennas, and vents for leakage, condition, and security. Prior to the accident flight, the airplane underwent an inspection only to the areas that had received maintenance since the previous OCF. Between the OCF on January 10 and the accident flight on January 14, the APU door was not accessed and no maintenance was performed in the area of the APU.

According to the airframe manufacturer, between 2005 and 2014, there were 5 other reports of in-flight APU service door events involving G200 airplanes, resulting in minor damage. In October 2008, the manufacturer issued a maintenance and operations letter (G200-MOL-08-0009) to remind flight crews to inspect all service and access doors for security prior to flight. On February 21, 2014, the manufacturer issued Maintenance and Operations Letter G200-MOL-14-0002, advising maintenance and operations personnel to verify that the APU service door was properly seated and latched when being secured.

Review of the previous in-flight APU service door events by the manufacturer revealed that, during manufacturing, the forward APU service door latches may have been trimmed to prevent interference with the frame, possibly resulting in insufficient overlap between the latches and the doubler. On May 30, 2014, the airframe manufacturer issued Service Bulletins 200-52-403 and 280-52-136, calling for inspection of the forward APU service door latches on G200 and G280 airplanes, respectively. Examination of the latches on the accident airplane immediately following the accident revealed the proper overlap between the latches and doubler.

NTSB Probable Cause

Maintenance personnel’s failure to properly secure the auxiliary power unit service door before returning the airplane to service, which resulted in substantial damage to the rudder.