On March 3, 1995, a Mooney M20C (registration N7836V) was involved in an aviation accident near Omak, WA. Investigators recorded the probable cause as: THE ELEVATOR PUSH ROD SEPARATION DUE TO FATIGUE. FACTORS CONTRIBUTING TO THE ACCIDENT WERE THE PILOT IN COMMAND'S FAILURE TO INSURE COMPLIANCE WITH THE AIRWORTHINESS DIRECTIVE AND THE FROZEN PUSH ROD BEARING. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During final approach at 500 feet AGL, the elevator push rod separated from bending fatigue, causing loss of elevator control. The monoball bearing was frozen and corroded. An AD requiring lubrication every 100 hours was 8 hours overdue.
Accident Sequence
The pilot was on final approach at an altitude of 500 feet above ground level when elevator control was lost. The loss occurred because the elevator push rod had separated.
Examination Findings
Post-accident examination revealed that the push rod separated due to bending fatigue. The monoball bearing in the assembly was found to be frozen and corroded.
Maintenance Record
The aircraft had undergone an annual inspection 108 hours prior to the accident. At that inspection, the flight controls were signed off as having been lubricated. However, no Airworthiness Directive (AD) listing was present to verify compliance with AD 73-21-01, which requires lubrication of the flight controls every 100 hours. At the time of the accident, this AD was 8 hours overdue.