What happened
On April 11, 2017, a Gulfstream GIV-X (G450) departed Salzburg Airport (LOWS) bound for Bangor International Airport, USA. Shortly after takeoff, the crew attempted to retract the landing gear but found it remained in the down and locked position. The crew realized that the landing gear safety pins had been left installed.
Following the discovery, the crew decided to perform a return landing at Salzburg. During the taxiing phase, the crew managed to remove the safety pins. However, as the pins were removed, the nose gear unexpectedly retracted, causing the aircraft to strike the ground with its nose.
The investigation
The Austrian SUB investigated the sequence of events, focusing on the preflight procedures and the mechanical behavior of the landing gear system. The investigation examined the cockpit voice recorder (CVR) and flight data recorder (FDR) to reconstruct the crew's actions and the aircraft's response. The investigation also reviewed the crew's preflight inspection and their decision-making regarding the safety pins, noting that the crew believed the pins did not need to be removed because they had been assured the aircraft would not be moved by ground staff.
Findings
- The primary cause of the accident was the failure to remove the landing gear safety pins during the preflight inspection.
- The crew had bypassed the standard procedure for installing safety pins during the previous night's postflight inspection, believing the pins were unnecessary since the aircraft was staying in place.
- There was a lack of familiarity with specific system procedures and a failure to strictly adhere to the checklist during the preflight phase.
- During the return to the airport, a communication error occurred regarding the intended runway, though the air traffic controller corrected the instruction to runway 15.
- The unexpected retraction of the nose gear occurred immediately upon the removal of the safety pins while the aircraft was on the ground.