CHI96FA314

While flying in instrument meteorological conditions (IMC), the pilot reported to approach control that the airplane had suffered a loss of its vacuum system. He requested a lower altitude in an attempt to descend into visual meteorological conditions (VMC). The pilot reported being unable to locate visual conditions. The airplane departed controlled flight and impacted the terrain. The primary vacuum pump was found inoperative with fractures of the rotor and vanes. The standby system was found not capable of operation due to a restriction in the system from the migration of sealing material or a gasket, blocking a hole drilled for the installation and operation of the standby system.

History of flight

On August 26, 1996, at 1032 central daylight time, a Piper PA-32R-300, N7133C, was destroyed on impact with the terrain and a post accident fire near Medford, Minnesota. The pilot reported a vacuum failure during cruise flight at 5,000 feet. The pilot sustained fatal injuries. The personal 14 CFR Part 91 flight was operating in instrument meteorological conditions. An IFR flight plan was on file. The flight departed Eden Prairie, Minnesota, at 1005, with the intended destination of Davenport, Iowa.

The owner of the airplane stated that on the day of the accident the airplane was operated from Davenport, Iowa, to Eden Prairie, Minnesota, arriving about 0930. He said that the airplane operated without incident during that flight. He said that after the passengers were deplaned, the pilot departed between 1000 and 1010.

At 1024:25, while cruising at 5,000 mean sea level (msl) the pilot of N7133C, reported to the Rochester (MN) Air Traffic Control Tower (ATCT), Approach Control, "I've got a vacuum system that's going out on me here. I'm having a little trouble holding my headings. I wonder if you could give me a little help here."

The controller continued to issue headings and cleared the airplane to descend to 3,000 msl for the next five minutes. The pilot indicated that he was experiencing instrument meteorological conditions and was requesting a descent to visual meteorological conditions. During the radio transmissions from the pilot, he made reference to being "still in it" twice.

The last known transmission received from the pilot was at 1029:51, when he radioed, "Okay, let me stay here for a little bit and see if we can get out of this... ." After this transmission, repeated attempts by the controller to contact the pilot were unsuccessful.

Personal information

The pilot was born December 29, 1931. He was the holder of a commercial certificate with privileges for single and multiengine land with an instrument rating for airplanes. His most recent biennial flight review was conducted on January 3, 1995. He was the holder of a third class medical issued on June 6, 1995. He had 1,789 hours of total flight time, 294 hours of instrument time with 27 hours in the preceding thirty days prior to the accident.

Aircraft information

The airplane was a Piper PA-32R-300, N7133C, serial number 36R-7680039. The airplane had accumulated 2,543 hours at the time of the accident. The airplane received an annual inspection on November 13, 1995. It had accumulated 133 hours since that inspection at the time of the accident. On January 10, 1994, a "Precise Flight" standby vacuum system was installed. The airplane had accumulated 305 hours since that modification.

Meteorological information

A weather reporting facility was located at Fairbault, Minnesota, 10 nautical miles northwest of the accident site. Seventeen minutes prior to the accident this station was reporting an overcast ceiling of 600 feet and visibility of 10 miles.

Communications

A transcript of the radio conversations between the pilot of N7133C and the Rochester ATCT Approach Control is attached as an addendum to this report.

Wreckage and impact information

The airplane wreckage was located in an open farm field. The initial ground scar was on about a 090 degree heading. A small quantity of green glass was found in the initial scar. The main wreckage was approximately 120 feet from the initial impact point and came to rest upright on a heading of 130 degrees. Foliage surrounding the wreckage showed evidence of fire damage and browning. Much of the fuselage was consumed by a post impact fire.

The left wing was fire damaged. Sufficient parts remained to indicate that the aileron, flap, and retracted main landing gear were in place. The control cables in the wing were not accessible. The remainder of the wing tip, which was consumed by fire, was found near the empennage.

The right wing was fragmented from impact spreading parts and fuel over the right side of the impact trail. The right wing tip and part of the right aileron were found near the initial impact point. The forward cabin door and part of the top right wing skin were found along the debris trail as was the right landing gear with part of the main spar and flap.

The forward fuselage was consumed in the post impact fire with the aft section sustaining impact damage. Control continuity was established from the tail surfaces to the pulley cluster below the control column.

The artificial horizon had impact damage; however, the internal gyro spun freely. The vacuum suction gauge had impact and fire damage. The needle was free and indicating "0." The airspeed had impact damage with the needle trapped at approximately 83 MPH.

The vertical stabilizer remained attached to the fuselage with impact damage to the lower portion of the leading edge. The rudder was in place with all hinges attached. The rudder control cables were attached and secure. The rudder balance weight had separated.

The horizontal stabilator displayed impact damage to the right side separating the outboard section and tip. The left side remained attached, but sustained impact damage. The hinge and attaching hardware were intact and secure. The trim drum showed a 7/8 inch extension with five threads showing. Piper Aircraft confirmed that this indication represented a neutral trim setting.

The engine displayed no external indication of malfunction. The crankcase was intact and oil was found in the sump. The vacuum pump was removed and disassembled. The drive coupling was melted and unrecoverable. The internal rotor was found fragmented with several vanes chipped or broken. A "Precise Flight" standby vacuum system was found installed. On disassembly it was noted that the sealing or gasket material had migrated over the hole drilled for the installation and operation of the standby system.

The propeller had separated from the engine at the initial point of impact and was buried in the terrain. One blade was bent aft about 45 degrees and showed twisting toward the low pitch position. The other blade was bent forward about 45 degrees and had twisting toward the low pitch position. Both blades sustained scoring and gouging of the leading edge and scratching and polishing of the camber face.

Medical and pathological information

An autopsy of the pilot was performed on August 26, 1996, at the Ramsey County (MN), Medical Examiner's Office. A toxicological examination was conducted on specimens from the pilot by the FAA Civil Aeromedical Institute. The volatiles detected in the toxicological examination of specimens from the pilot were attributed to "...postmortem production." The presence of Hydrochlorothiazide was attributed to a prescription drug taken by the pilot and reported on his most current physical examination. Two additional prescription drugs were reported on the same physical examination report, but were not detected in the toxicological testing.

Fire

A post impact fire consumed portions of the airplane and engine. There was aviation fuel present. Ground scars and heat damaged foliage indicate a wide spread ground fire. The specific ignition source was not identified.

Additional information

Parties to the investigation were the Federal Aviation Administration, Flight Standards District Office, Minneapolis, Minnesota, and Piper Aircraft, Vero Beach, Florida.

The wreckage was released to representatives of the owner on September 24, 1996.