ERA18LA032 · Piper PA 34-220T

The private pilot stated that the airplane's left engine had recently started to leak a significant amount of oil; however, two mechanics looked at the engine the day before the accident flight, and the source of the leak could not be located. On the day of the accident, the pilot topped off his fuel tanks and put 2 quarts of oil in the left engine, bringing the oil level up to 7 quarts. He then departed on a long cross-country personal flight. About 10 to 15 miles from the destination airport, the left engine low-oil-pressure light came on. When the airplane was 5 miles from the airport, the left engine lost total power, and the propeller feathered. The pilot chose to land downwind due to having only one working engine; however, his approach was too fast and too high, so he decided to go around. As the airplane began a shallow climb, the pilot entered a left turn to avoid mountains. While in the turn, he realized that he was not going to make it back to the airport and increased the right engine's throttle to full power. This overboosted the turbocharger-equipped engine, which stopped producing power. The airplane stalled and impacted trees.

A postaccident examination of the airplane revealed streaks of oil on the top and under the left engine cowling just aft of the oil filler door. Oil was also observed under the left wing. The left engine's oil filler cap was still on the filler neck but did not seat properly and would partially lift off the seat if it was pulled upward. The cap's locking mechanism was corroded, and the locking tangs were bent. A teardown examination of the left engine revealed that the No.1 and No. 2 connecting rods had failed, and their associated crankshaft journals displayed heat distress, consistent with oil starvation. The No.1 piston exhibited signatures of detonation. It was not determined what caused the piston to detonate, but a download of the onboard engine analyzer revealed that the cylinder head temperature was higher on that cylinder for most of the accident flight. The exact source of the oil leak could not be determined based on available evidence. The pilot made an improper decision to fly the airplane with a known oil leak, which ultimately led to the total loss of engine power due to oil starvation. Further, although the pilot decided to land downwind due to having only one working engine, the tailwind was significant, and this decision led to his attempted go-around and loss of control.

Verbatim NTSB analysis and probable cause from the NTSB dataset