Incident Details
The pilot reported that during the approach to runway 27L with wind from the southwest at 15 knots and no gusts, all gears were confirmed down and locked by the down-and-locked lights. The landing was performed first on the left main landing gear, then the right main, and finally the nose gear. During the landing roll, when the airplane was almost stopped, the pilot stated, "I felt like a blown tire, right wheel zig zag and suddenly I could not control turn to the right and landing gear collapse." The airplane came to rest upright.
Examination Findings
Post-incident examination revealed scrubbing on the lower inboard portion of the right main landing gear tire and the wheel assembly rotated nearly 90 degrees. The upper and lower link assemblies of the right main landing gear were separated; the attach hardware remained in the upper link assembly. The bolt securing the upper and lower link assemblies had pulled through the lower link assembly on the nut end. Two washers on the nut end, approximately 0.023 inch thick, were damaged. A washer approximately 0.061 inch thick was installed under the bolt head. A non-mandatory Cessna Service Information Letter specifies installing 0.066-inch thick washers on both the head and nut end of that bolt. No record existed in the maintenance records indicating compliance with this service letter.
Testing of the right main landing gear actuator found that the unlocking pressure was too high and one of four lock keys was improperly installed. The operator had performed unlock pressure testing on the actuator approximately two months before the incident in accordance with a service bulletin (SB). The SB states to replace the actuator if unlocking pressure is not within specification; the actuator was not replaced. No serviceable tag was in the maintenance records, and no determination was made regarding when or where the actuator was overhauled. The FAA-approved inspection program for the operator did not list inspection of the main landing gear link assemblies, unlike the Cessna Progressive Care Program.