On September 12, 1983, a Beech B-24R (registration N9196S) was involved in an aviation accident near Potomac, MD. Investigators recorded the probable cause as: The failure of a connecting rod due to retaining bolts that were not properly torqued during a recent major overhaul. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A forced landing occurred after the engine lost power. Investigation revealed that connecting rod retaining bolts were not properly torqued during a recent major overhaul.
What happened
The aircraft executed a forced landing in a field of rye grass following an in-flight loss of engine power. The pilot was unable to maintain altitude and selected the field as the nearest suitable area for an emergency touchdown.
The investigation
Post-accident examination of the aircraft revealed that a connecting rod had failed catastrophically. Further inspection by Federal Aviation Administration (FAA) personnel determined that the root cause was mechanical in nature. Specifically, the bolts retaining the connecting rod were not properly torqued during a recent major overhaul of the engine.
Findings
The failure of the connecting rod was directly attributed to the improper installation torque on its retaining bolts. This maintenance error led to the loss of power and the subsequent forced landing. The owner did not file an official accident report, citing that the event did not meet the regulatory definition of an accident at the time.
Safety message
Proper torque specifications during engine overhaul are critical for maintaining structural integrity of internal components like connecting rods. Maintenance personnel must ensure all fasteners are torqued to manufacturer standards to prevent in-flight failures.
Probable cause
The failure of a connecting rod due to retaining bolts that were not properly torqued during a recent major overhaul.