What happened
The incident occurred while the aircraft was in the process of landing. During this phase, the right main landing gear experienced a catastrophic mechanical failure. The scissors bolt and bushing assembly pulled through the designated hole in the scissors mount. This structural failure allowed the landing gear to rotate 90 degrees from its intended position, rendering it unable to support the aircraft's weight upon touchdown.
The investigation
An examination of the maintenance records and physical components revealed the root cause of the mechanical failure. It was determined that an incorrect washer had been installed in the scissors assembly during recent maintenance work. Specifically, a standard 5/16-inch washer was used instead of the component required by the manufacturer's specifications.
Findings
The investigation identified a direct violation of the Cessna Parts Manual requirements. The manual explicitly calls for an AN960-5/16 washer for this specific assembly. The installation of a non-compliant standard washer led to the bolt and bushing pulling through the mount under load, causing the gear to rotate incorrectly.
fuel exhaustion is not the cause here; rather, the critical causal fact was incorrect washer installation. The failure was mechanical and preventable had the correct part been used. Cessna 172 type aircraft rely on precise hardware specifications for landing gear integrity. This event highlights the importance of using only approved parts during maintenance.
Safety message
Maintenance personnel must strictly adhere to manufacturer parts manuals when performing repairs. Using incorrect or non-standard washers can lead to catastrophic structural failures under operational loads.