What happened
On September 8, 1978, a Fuji FA-200-180A0 aircraft, registration HB-EUH, was conducting a visual flight from Birrfeld to Basel-Mulhouse with one passenger on board. Approximately six minutes after takeoff, while cruising at 2,500 feet, the pilot noticed a rise in oil temperature. Following this, the engine began knocking, and the temperature climbed to the maximum limit of the gauge.
A loud bang was heard in the engine compartment, followed by intense vibrations, after which the engine ceased functioning entirely. Unable to locate the nearby Triengen airfield, the pilot attempted an emergency landing near an N2 motorway construction site. During the approach, the aircraft's low altitude and insufficient speed prevented the pilot from completing the turn into the landing pattern. The aircraft struck an earth embankment approximately 6 meters high, causing a violent fire. The occupants sustained two light injuries, but the aircraft was destroyed.
The investigation
The investigation focused on the mechanical failure of the Lycoming 0-360-A5 AD engine. Upon disassembly, investigators found extensive internal damage, including a hole in the crankcase caused by the movement of valve tappets from cylinder number two. The third piston was found welded to its cylinder, and the connecting rod for cylinder number two had separated from the crankshaft.
Technicians discovered that the bearing cap for the second connecting rod was severely deformed and fragmented. The bolts securing this cap had failed. Furthermore, the investigation revealed that the pilot did not follow the emergency procedures outlined in the Airplane Flight Manual, specifically regarding the canopy release, which forced the occupants to break the glazing to escape the fire.
Findings
- The primary cause of the engine failure was the separation of the number two connecting rod from the crankshaft.
- The failure of the bearing cap bolts allowed lubricant to escape through the crankshaft bores, leading to a loss of oil pressure and the subsequent seizure of the third piston.
- The failure of the bearing cap bolts was attributed to improper tightening during maintenance; a bolt had loosened and subsequently snapped under load.
- The pilot's approach to the emergency landing was deemed inappropriate, as the aircraft's low altitude and speed prevented a controlled arrival at the intended site.
Safety action
- The investigation noted that the failure to follow emergency instructions regarding the canopy could have resulted in more severe injuries or fatalities.