What happened
The Piper PA-28 departed on a local pleasure flight. Shortly after takeoff, the pilot observed that the engine was running roughly and noted a loss of oil pressure. The engine subsequently seized, forcing the pilot to make an off-airport landing in a snow-covered field.
The investigation
A post-crash examination of the aircraft revealed that the vacuum pump was physically missing from the airframe. Investigators were unable to determine the reason for its absence.
Findings
The primary contributing factor was the missing vacuum pump, which led to engine seizure and the subsequent forced landing.