21st of August 2021, Failed Pip Pin, Blog #752
- V2Aviation
- 6 minutes ago
- 3 min read
A Gulfstream Aerospace G-IV was scheduled to operate a private flight (according to Title 14 Code of Federal Regulations Part 91) from Fort Lauderdale-Executive Airport (Florida, USA) to Las Vegas-McCarran International Airport (Nevada, USA), on this day in aviation history, the 21st of August 2021.
Onboard the aircraft were a crew of four and ten passengers.
With all flight preparations were completed, the aircraft taxied to runway 9. After receiving take-off clearance, the throttles were pushed forward and the aircraft started to accelerate as expected. Standard call-outs were made and all was normal until the aircraft reached a speed of about 100 to 110 knots. At that point during the take-off roll, a terrible nose wheel shimmy started which increased in intensity. Shortly after that, the nose of the aircraft dropped a bit, making the Pilot In Command (PIC) believe the tires of the nose landing gear had failed.
The co-pilot had noticed the onset of the nosewheel shimmy at a speed of approximately 80 knots, which increasingly got worse to the point where the PIC aborted the takeoff by applying the wheel brakes and selecting reverse thrust.
The aircraft veered off the runway, and the right wing and right main
landing gear struck a concrete slab holding approach lighting equipment. The airplane came to a stop shortly after impacting the concrete slab in a sandy grass area about 200 ft to the right of the runway 9 centerline.
As the PIC completed the emergency shutdown/evacuation checklist, the co-pilot immediately got up, opened the main cabin door, and assisted the passengers in the emergency evacuation. There were no injuries.
Damage to the aircraft was extensive;
The right main landing gear punctured into the wing.
The nose landing gear had sheared from the fuselage and was found on the runway.
The fuselage and wing also sustained damage.
All major components of the nose landing gear (NLG), which had sheared from the airplane, were located on or near runway 9. The first item located on the runway, farthest from the main wreckage, was the NLG pip pin (upper torque link pin). It was found about 2,215 ft from the main wreckage. The bulk of the NLG came to rest near the runway centerline about 900 ft farther down the runway from the pip pin. The safety pin that was normally installed through the pip pin was found intact, still attached to the separated NLG by its lanyard cord, not inserted in the pip pin.
The accident was reported to the National Transportation Safety Board and an investigation was launched. As part of the investigation, the crew and ground crew were interviewed.
During these interviews, the following statements were made;
After towing, the FBO staff noticed that the locking balls and plunger button were stuck in (depressed) on the pip pin of the upper torque link pin.
The pip pin of the upper torque link pin was installed by the FBO staff; however, they did not install the safety pin as it would not fit due to the stuck plunger.
The ramp supervisor was informed, and the ramp supervisor informed a crew member about the issue with the pip pin.
The pip pin was checked and found installed by the crew during the pre-flight.
The crew had no recollection of whether the safety pin was installed on the pip pin.
The crew had no recollection of being informed by the FBO supervisor about the issue with the pip pin.
View of the NLG and pip pin installed during postaccident examination testing (Source & © NTSB)
On the 10th of May, 2023, the NTSB published their final report, with the following probable cause and findings;
The pilot-in-command’s (PIC) and second-in-command’s (SIC) failure during the preflight
inspection to ensure that the nose landing gear’s pip pin was properly installed, which resulted in the separation of the pip pin during takeoff. Contributing to the accident was the ground crew supervisor’s failure to inform the PIC or SIC of the anomaly concerning the pip pin following a towing operation.
The NTSB final report, which served as the source for this blog, with full details of the investigation, can be accessed by clicking on the file below. The report also provides access to the NTSB Docket.
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