On April 25, 2002, a Cessna 421C (registration N237SM) was involved in an aviation accident near Tampa, FL. Investigators recorded the probable cause as: The upper barrel of the landing gear fractured due to fatigue cracking caused by improper machining during the manufacturing process. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot aborted a landing following an abnormal touchdown due to suspected mechanical issues, leading to a secondary landing on a grass area.
What happened
Following a landing, the pilot of the Cessna observed an abnormal touchdown and identified a potential mechanical issue. The pilot aborted the landing and cycled the landing gear twice, noting that the gear unsafe light remained illuminated. After communicating with tower personnel, who confirmed damage to the left main gear, the pilot returned to the departure airport. After burning approximately 1.5 hours of fuel, the pilot attempted another landing but touched down on the nose and right main landing gears on the grass adjacent to the paved runway.
The investigation
An examination of the landing gear determined that the upper barrel (part number 5141002-11) had fractured. This fracture occurred above a brazed-on collar due to fatigue cracking. The investigation traced the cause of the fatigue cracking to improper machining performed after the barrel was assembled during the manufacturing process.
Probable cause
The upper barrel of the landing gear fractured due to fatigue cracking caused by improper machining during the manufacturing process.