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21st of August 2021, Nose Landing Gear Failure, Blog #613

After being towed to the parking stand (at Fort Lauderdale-Executive Airport, Florida USA), from which it would depart, the Nose Landing Gear upper torque link arm was reconnected on a Gulfstream Aerospace G-IV by the ground crew. However the locking balls of the pip pin would not release, and the locking balls were stuck in the retracted position. This meant that the safety pin could not be inserted into the Pip pin. The ground crew informed the ramp supervisor, who subsequently informed one of the crew members (later determined to be the observer pilot) when they arrived at the aircraft. Stating "Per tow team, check your nose pin". (the cockpit crew consisted of a Pilot in Command, Co-pilot and observer pilot). The crew later stated they were never informed about an issue with the Pip pin.

The sheared-off Nose Landing Gear assembly on the runway (Source; baaa-acro.com © Unknown)


After completing the required pre-flight activities 10 passengers boarded the aircraft and the engines were started for the cross-country flight to Las Vegas McCarren International Airport (Nevada, USA). As the aircraft taxied to runway 09, all systems and indications were normal. After receiving the take-off clearance the engines were spooled up and the aircraft started to accelerate down the runway. Around 80 knots the co-pilot noticed a light shimmy and rattle through the rudder pedals. Around 100 knots the Pilot in Command felt a heavy shimmy from the nose landing gear that became worse and worse. It then appeared to him that the nose landing gear tires had failed.

The aircraft in its final position (Source: baaa-acro.com © KFXE Fire & Rescue Services


The take-off was immediately aborted by applying the footbrake and selecting reverse thrust. As the aircraft started to decelerate it veered to the right and left the paved surface of the runway. With the crew unable to control the direction of the aircraft. The right main landing gear and wing struck a concrete slab holding approach lights, coming to a stop shortly afterwards 200 feet from the runway centreline. An emergency evacuation was initiated there were no injuries. Damage to the aircraft was extensive, the right main landing gear was pushed upwards through the upper surface of the wing. The nose landing gear had sheared off the airplane and was found on the runway. 900 feet (274 meters) from the final position of the aircraft while the pip pin was found about 2215 feet (~675 meters) from the main wreckage.

The failed main landing gear (Source; baaa-acro.com © FAA)


The aircraft manufacturers' manuals contained detailed instructions on how to remove and instal the Pip pin for towing operations. Besides these instructions, it also contained the following caution;


"DEFECTIVE OR IMPROPERLY INSTALLED PIP PIN CAN CAUSE EXTENSIVE DAMAGE TO AIRCRAFT."


Furthermore, the preflight checklist called for a check of the Nose Landing gear and wheels, and that the torque link must be "PINNED / SAFETIED"

The accident scene (Source; baaa-acro.com © Unknown)

An investigation into the accident was launched by the National Transportation Safety Board (NTSB). On the 10th of May 2023, they published their detailed report, which served as the source for this blog.

They concluded that the probable cause(s) of the accident were;


"The pilot-in-command’s (PIC) and second-in-command’s (SIC) failure during 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 detailed NTSB report into this accident is accessible by clicking on the .pdf file below;

21Aug2021 G.IV Landing Gear Failure
.pdf
Download PDF • 3.84MB

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