Accident Overview
On approach, while stabilized on final approach, the aircraft pitched up slightly, yawed, and then rolled left to an inverted attitude before crashing into a canal.
Witness Observations
Several witnesses reported that the left propeller was windmilling; one stated it had stopped. Two witnesses noted smoke trailing from the aircraft. One witness reported a fine mist of oil falling on his windshield after the aircraft passed overhead.
Physical Evidence
Upon recovery from the canal, the left propeller was found in the feathered position, while the right propeller was near its low pitch stops. The left propeller dome was depleted of air pressure, and no oil was found in the left engine case. An oil film was present on the bottom of the left engine, left flap, and left stabilizer. Further examination revealed that an oil interconnect line (Piper p/n: 920024-811) had failed inside its fireproof covering. The hose was eight years old, exceeding its recommended replacement interval of five years, and had been installed with a small bend radius. The left engine also showed evidence of heat and wear consistent with lack of oil.
Probable Cause
The official probable cause is as follows: Occurrence #1 involved a partial loss of engine power due to mechanical failure, specifically a deteriorated, life-expired oil hose that failed completely, resulting in total oil loss. This was attributed to inadequate inspection and failure to replace the hose by maintenance personnel. Occurrence #2 was a loss of control in flight because the pilot did not maintain airspeed (Vmc). Occurrence #3 was an in-flight collision with terrain/water during an uncontrolled descent.