N819KS

On June 5, 2023, about 1517 Pacific daylight time, a Cessna 172R, N819KS, was substantially damaged when it was involved in an accident near Santa Monica, California. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight.

The pilot stated that he was performing a maintenance test flight (the airplane’s first flight) following a repair for a collision with a fuel truck that occurred about one month earlier. On the day of the accident, he inspected the nose landing gear assembly and “saw nothing out of sorts” that would have caused him to cancel the flight. After a high-speed taxi he determined that the airplane was safe to fly in the airport traffic pattern. The pilot departed runway 21, remained within the airport traffic pattern, and touched down normally on the departure runway. During landing roll, as the nose landing gear contacted the runway, it began to shimmy. The pilot applied back pressure to the control yoke to keep the airplane’s weight off the nosewheel; however, once the airplane slowed the nose wheel shimmy intensified. Subsequently, the pilot heard a sound that resembled a piece of metal strike the lower engine cowling.

The airplane veered left despite the pilot’s attempts to correct the movement with right rudder. His attempt to apply the brakes also exacerbated the turn and he continued to use aerodynamic braking with back pressure on the control yoke. The airplane then veered left aggressively and, when the pilot attempted to reapply the brakes, the right wing dipped and collided with the ground. The airplane nosed over and came to rest inverted, which resulted in substantial damage to the rudder.

A bolt from the nose wheel torque link assembly was found on the runway during a sweep for foreign object debris following the accident. In addition, the torque link had separated from the nose wheel steering arm assembly at the upper bolt (see Figure 1). According to the airplane maintenance manual,

“The torque links give a mechanical link between the top and bottom parts of the shock strut and help keep the nosewheel aligned with the airframe.”

The illustrated parts catalogue shows that the upper torque link connects to the nose gear steering arm assembly and the lower torque link connects to the nose wheel fork.

Figure 1: Nose wheel torque link and bolt from accident

Bolt Examination

A National Transportation Safety Board Materials Laboratory examination found that both the upper and lower torque link bolt measurements and thread profiles were consistent with the proper bolt for the installation. The bolthead had separated from the bolt shank, but the corresponding castellated nut and cotter pin were secure in place. The fracture surface had directional dimples consistent with shear overstress.

Prior Damage

In May 2023 the airplane collided with a fuel truck as it was being towed by the operator. The airplane owner videotaped the damage to the airplane, which showed a bent tow point and a curved bolt with a castellated nut protruding from the upper torque link to nose gear steering arm assembly connection. According to an invoice, the damage was inspected and 10 shock mounts on the cowling were replaced to prepare the airplane for a ferry flight as the damage, including the strut, was going to be repaired by another maintenance facility. The operator stated that the instructor was then asked to complete the maintenance flight (accident flight) after the airplane was serviced to ensure it was airworthy before the ferry flight.

Figure 2: Damage to nose gear after collision with truck (May 2023)