What happened
On May 2, 2017, at approximately 08:40 LT, a Piper PA-3/1 (registration LV-WIZ) was operating a ferry flight from San Fernando, Argentina, to Laguna del Sauce International Airport (SULS), Uruguay. The aircraft was carrying two pilots and six passengers.
Following a standard landing on runway 26, the crew performed a 180-degree turn on the runway as instructed. During the subsequent taxiing phase, the crew noticed a smell of rubber and a tendency for the aircraft to pull to the right. The airport tower subsequently alerted the crew to visible white smoke emanating from the nose gear.
Upon inspection, the pilot found that the nose wheel was misaligned and rubbing against the fork. The inspection revealed that the tire rubber was contacting the attachment fork due to the absence of specific securing components. All eight occupants evacuated the aircraft safely on the taxiway. There were no injuries, and the aircraft sustained damage only to the nose gear assembly.
The investigation
The CIAIA investigation focused on the mechanical state of the nose gear and the maintenance history of the aircraft. Investigators examined the nose gear assembly and identified that four specific parts—including a bolt, a nut, and two plugs—were missing from the assembly.
Technical analysis ruled out the possibility of the nut loosening due to its self-locking design, and determined that the bolt had not failed due to structural stress. Instead, the investigation established that the lateral forces exerted during the low-speed turns during the backtrack caused the bushings to shift out of their seats, leading to the wheel exiting its axis.
Furthermore, the investigation scrutinized the maintenance records of the facility responsible for the recent 500-hour inspection. It was noted that the aircraft had been released for service without the presence of an inspector. The investigation also reviewed the crew's weight and balance calculations, noting discrepancies between the crew's mental estimates and the actual recorded data.
Findings
- The primary cause of the incident was the improper execution of the nose wheel removal, inspection, and installation task.
- The absence of four critical components (a bolt, a nut, and two plugs) allowed the wheel to displace from its axis.
- Lateral forces during taxiing maneuvers caused the bushings to move out of position.
- There was a lack of operational safety culture regarding the verification of maintenance tasks and the inspection of aircraft release.
- The crew's pre-flight inspection was compromised by complacency and was conducted using only a flashlight in low-light conditions.
- Discrepancies were found in the weight and balance documentation and the accuracy of the crew's manual calculations.