Accident Overview
A pilot operating under a VFR flight plan made contact with Seattle Air Route Traffic Control Center (ARTCC) to obtain an IFR clearance. Subsequently, he requested and received clearance to climb to 15,000 feet above mean sea level (MSL). During the climb, ARTCC temporarily lost radar contact with the aircraft and asked the pilot to report when reaching 15,000 feet, which he did at 1329 Pacific Daylight Time (PDT).
Pilot Reports
Approximately one minute later, the pilot reported a loss of vacuum system pressure, stating that he had lost "gyro suction" and would be using "partial panel" instruments. He also reported that some instrument meteorological conditions (IMC) remained, that he was in and out of clouds, and that he had encountered light rime icing conditions. Shortly thereafter, ARTCC lost both radio and radar contact with the airplane.
Witness Account
A witness on the ground heard the sound of the engine revving just before the airplane crashed.
Wreckage Examination
Examination of the wreckage revealed that the wings and empennage had separated in flight. Evidence indicated that the wings had failed downward. The fuselage skin forward of the empennage was ripped and torn, with numerous rivets torn through the seams.
Vacuum Pump Inspection
A check of the vacuum pump showed evidence of seizure following long-term contamination and wear from engine oil.