Piper PA-22-108 N4798Z accident near Lewiston, Idaho

Probable cause

The pilot’s inadequate postmaintenance and preflight inspections, which resulted in the separation of the left main wheel after takeoff. Contributing to the accident was the improperly secured left main wheel spindle nut.

NTSB analysis

After departure from an uncontrolled airport, ground personnel advised the pilot that they saw the left main wheel and tire fall off the airplane. The pilot decided to continue flight to a nearby controlled airport, where, after flying around to decrease the amount of fuel on the airplane, he landed. The airplane departed the right side of the runway and tipped onto its nose, which substantially damaged the right wing spar. The pilot reported that he observed no anomalies when he examined the main wheel bearings for the correct spindle nut tension 2 days before the accident. However, he believes that the left wheel spindle nut cotter pin was inadvertently omitted or not installed correctly when he reinstalled the wheel on the airplane. He said that a more thorough inspection of the wheel bearing service work should have been performed, and that a more thorough preflight inspection could have caught the problem.

Text from the NTSB. Open the NTSB docket for WPR12CA401 for the full record.