What happened
On September 12, 1984, a Piper PA-28R-201T aircraft with registration D-EMCY departed from Schwaighofen airfield in Germany for a mixed VFR/IFR flight to Bilbao, Spain. The pilot was accompanied by two passengers. Approximately one hour into the flight, while cruising at Flight Level 150 west of the Kloten VOR, the pilot noticed a drop in engine oil pressure. He reported the issue to Zurich Radar and requested to break off the flight and descend.
As the aircraft descended to Flight Level 130, the engine RPM spiked to 3000, followed by a rapid loss of oil pressure and a rise in oil temperature. Loud noises emanated from the engine compartment, prompting the pilot to shut down the engine entirely. He requested radar guidance to a closer landing site and was cleared for Triengen aerodrome on a heading of 210 degrees.
At approximately 5,000 feet, the pilot spotted the airfield to his left and contacted radar control. He began his approach but struggled to identify the runway or determine wind direction due to the urgency of the situation. Realizing that his altitude and distance made overshooting the short runway inevitable, he executed a full right-hand turn at 4,000 feet with gear and flaps extended. This maneuver caused significant altitude loss, forcing him to fly below two electrical wires in the approach sector.
Shortly before crossing a road perpendicular to the approach path, the aircraft touched down at roughly 90 knots. The nose gear collapsed as it hit the ground, causing the plane to bounce over the road, rotate 90 degrees to the right, and come to a stop about 200 meters past the threshold of Runway 15. The aircraft was destroyed, and significant crop damage occurred.
The investigation
The SUST examined the pilot's qualifications, which were valid, and the aircraft's airworthiness certificate, last inspected in May 1984. The engine, a Continental TSIO-360 with turbocharger, had a total time of approximately 710 hours. Pre-flight checks showed no oil leaks, and oil temperature and pressure were normal at startup.
Post-crash inspection revealed the fuselage and tail covered in oil, with the engine completely empty. Oil had exited through the crankcase breather. The investigation found that the pilot had noticed abnormal oil consumption and leaking since spring 1984. In June 1984, two cylinders with low compression were repaired. Later, during a 100-hour inspection in August 1984, all six cylinders showed low compression and were replaced along with pistons and rings.
Engine teardown confirmed that the crankshaft and connecting rods failed due to total oil loss. No defects in the lubrication system or fuel injection were found that could have caused the initial leak. The weather at the time was clear with high pressure, visibility over 20 km, and variable winds of 2 knots.
Findings
The accident was caused by a failed emergency landing following an engine failure due to oil loss. Contributing factors included:
- Improper approach planning: The pilot's decision-making under stress led to a high-energy turn that resulted in altitude loss and inability to align with the runway.
- Maintenance issues: The oil loss was likely caused by excessive clearance between pistons and cylinders after previous repairs, leading to blow-by and overpressure in the crankcase. This was exacerbated by improper engine break-in procedures and high thermal stress following the cylinder replacement.
The pilot's decision to continue flying toward Bern after noticing low oil pressure was deemed inappropriate. Had he declared an emergency earlier, immediate assistance for a landing at Zurich would have been possible.
Safety action
The report highlights that despite previous repairs by German maintenance facilities, the root cause of the oil loss was not identified. The combination of improper engine break-in and high thermal stress after cylinder replacement led to accelerated wear and eventual catastrophic failure. No specific safety recommendations were issued in this historical context beyond the implicit need for thorough diagnosis of recurring oil loss issues.