Stockton, CA, USA
N3424Q
Cessna 320E
While exiting the runway after landing, the right main landing gear collapsed, and the right wing struck the runway. The pilot reported that this was the first flight after an annual inspection in which the landing gear had been rigged. In addition, he had the failed components sent to a metallurgical laboratory. The owner submitted these findings to the Safety Board. The inspection report indicated that the right main landing gear had been rigged so that the gear tension terminated prematurely. This prevented the downlock link from reaching its full over center, locked position. This caused the side loads on the landing gear to be transmitted through other landing gear linkage components, instead of through the downlock link. The other components were not designed to carry those loads, and consequently failed in overload, resulting in the collapse of the landing gear while taxiing off the runway.
On April 1, 2007, at 1100 Pacific daylight time, a Cessna 320E, N3424Q, collapsed the right main landing gear while exiting runway 29L at Stockton Metropolitan Airport (SCK), Stockton, California. The pilot/owner operated the airplane under the provisions of 14 CFR Part 91 as a personal flight. The airplane sustained substantial damage. The pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed for the local area flight that departed SCK about 1000. No flight plan had been filed. According to the pilot, this was the first flight after an annual inspection. He had flown to Calaveras County-Maury Rasmussen Field Airport (CPU), San Andreas California, refueled, and then flew back to SCK. The pilot noted no mechanical problems with the airplane during the flight until he reached SCK. He stated that the landing and landing rollout were normal. While slowing down to exit the high speed taxiway, he engaged the left rudder to turn to the left, and the right main landing gear collapsed. The right wing struck the runway, and right propeller and right horizontal stabilizer were also damaged. The pilot reported that he exited onto the taxiway at 20 miles per hour (mph). He further reported that during the annual inspection the landing gear had been rerigged. Reported winds at the time of the accident were variable at 3 knots. TEST AND RESEARCH According to a Federal Aviation Administration (FAA) inspector, the right main landing gear bellcrank (part number 0841225-10) strut attachment bolt (AN4-25A) sheared. This placed an increased load on the remaining main strut attachment clevis ears, which caused the ears to fail and the down lock link assembly to collapse. The FAA inspector stated that his inspection was not able to ascertain whether or not the landing gear had been rigged improperly. The pilot had the landing gear independently inspected. According to the inspection report, the right side main landing gear fork bolt was deformed in an outward direction at the fork-to-bolt junction. The right main landing gear down indicator switch had been rigged to a point where it made contact at the "earliest possible moment during landing gear extension." The right main landing gear fork bolt had been adjusted to what appeared to be its full outboard limit. The right main landing gear outboard push pull tube rod ends had been adjusted to their shortest possible length. The right landing gear lock link end fitting and the right main landing gear bellcrank were sent to a metallurgical laboratory that reported that the components had failed in overload. The aircraft logbook entry indicated that the annual inspection had been completed and returned to service in an airworthy condition on April 1, 2007. The entry stated in part that the landing gear had been rigged in accordance with Cessna's service manual.
The landing gear collapsed during taxi as a result of incorrect rigging of the landing gear by other maintenance personnel that prevented the landing gear downlock from functioning as designed.
Source: NTSB Aviation Accident Database
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