NTSB Factual Report

HISTORY OF FLIGHT

On September 22, 1996, at 1125 central daylight time (cdt), a Cessna 172F, N5373R, operated by a private pilot was destroyed when during cruise flight, the airplane's engine lost partial power. The airplane subsequently impacted into a corn field one mile east of Saint Clair, Minnesota. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91. No flight plan was on file. The pilot sustained fatal injuries. The local flight originated at Waseca, Minnesota, at 1120 cdt.

A witness, who was in his garage, first heard the airplane make a back firing sound. The witness went out of his garage and observed the airplane coming out of the north, heading south toward his house at low altitude. When the airplane was over the witness' house, it turned to the southwest. The witness went around to his back yard to get a better view of the airplane. The witness saw the airplane initiate a "fast" left turn and then go straight down into a corn field.

Three other witnesses were in a shed loading tools into a truck when they heard a steady series of bangs. The first witness described the sound "like a shotgun going off." The witnesses went out of the shed and observed the airplane coming toward them from the northeast. The second witness said the airplane looked as if it was "slowly losing altitude." The witness said the airplane went over their yard at about 500 to 600 feet above the ground and headed south to southwest rocking its wings slightly. All three witnesses got into a car and followed the airplane. The second witness saw the airplane initiate a right turn to the west. She said that the engine sound changed from banging to a sputter. The second witness said the airplane continued its turn to the north and started come back toward them. The witness turned away momentarily and said that she heard no noise. When she looked back toward the airplane, she saw the airplane in a nose dive approximately 30 feet above the corn field. The third witness said he saw the airplane go straight down into the corn field. He also said that the airplane "got about half a turn," toward the east before it hit. The second witness said that she heard the sound of the impact.

PERSONNEL INFORMATION

The pilot had 301.9 total flying hours in single-engine land airplanes and 248.2 hours in the C-172F airplane.

The pilot had a biennial flight review in a Cessna 172 airplane on January 2, 1996

AIRCRAFT INFORMATION

The airplane was owned and operated by the pilot. It was used crop monitoring and pleasure. The airplane had an annual inspection performed on January 18, 1996.

According to the manufacturer, the airplane was manufactured in 1965. The airplane had a total airframe time of 1,454 hours.

WRECKAGE AND IMPACT INFORMATION

The NTSB on scene investigation began on September 23, 1996, at 1400 cdt.

The wreckage was located in a corn field 93 feet west of Blue County Road 49, a north-south running gravel road, and 1/4 mile north of Blue County Road 15, an east-west running paved road, one mile east of Saint Clair, Minnesota.

Examination of the accident site revealed a 4-foot long, 1-foot wide ground scar within the center of 38-foot long, east-west running crush area within the corn field. The ground scar measured 10 inches at its deepest point. The propeller spinner was embedded at the north end of the ground scar. It was crushed inward, broken and separated from the propeller hub. Pieces of clear plexiglass from the windscreen were found within the ground scar and scattered around its perimeter. Corn stalks within an 8-foot radius of the scar, were evenly chopped off 38 inches up and 12 inches up from the ground. Approximately 22 feet west of the main ground scar, at the end of the corn field crush area was an 11-inch long scar. Pieces of red glass, a broken airplane position light bulb and the left wing tip were found 24 feet west of the main ground scar along a 270-degree magnetic heading. The wing tip was separated at the rivet line and broken 15 inches inboard of the edge into several pieces.

The main wreckage consisted of the remaining airplane components. The airplane was resting upright on its landing gear and tail approximately 15 feet east of the main ground scar. Its longitudinal axis was oriented on a 290-degree magnetic heading.

The engine, cowling, propeller and firewall were crushed predominately inward to the forward crew compartment. This area was also bent upward and to the right approximately 50 degrees. One of the two propeller blades was bent aft at a 40-degree angle, approximately 7 inches outboard of the hub. The other propeller blade was bent slightly back. Both blades exhibited torsional bending and chordwise scratching.

The engine mounts were broken and bent left and upward along with the nose gear. The carburetor was broken off and lying on the ground in front of the main wreckage. The carburetor throttle plate was open at a 45-degree angle. The oil pan, muffler and exhaust system was crushed up and inward. The main landing gear struts, wheels and tires showed no damage.

The cockpit frame was broken at the top center, just aft of the windscreen frame. The instrument panel was crushed aft and up, and was broken from beneath. The majority of cockpit instruments were destroyed. The pilot and passenger seat were bent upward into the broken instrument panel. The left cabin door was bent outward diagonally. The forward frame of the door was bent inward at the top front corner approximately 10 inches. The right cabin door was found open and bent approximately halfway up at the base of the window. The aft crew compartment interior was intact. The aft cabin ceiling was bent forward, down and approximately 15 degrees to the left. The rear windows were broken out. The fuselage, just aft of the crew compartment was broken and bent down 50 degrees so that the bottom of the rudder was resting on the ground. The fuselage skin was broken open beginning at the base of the rear window frame. The fracture proceeded down and aft for approximately 12 inches. The floor of the airplane in this area was crushed in and upward. The fuselage aft of the fracture showed minor buckling. The empennage was intact.

The left wing was crushed along the entire span of the leading edge, from the leading edge aft to the main spar. The crush line displayed showed an 85-degree angle to the airplane's longitudinal axis. The leading edge was also bent upward and aft approximately 35 degrees, beginning 7 feet outboard of the wing root and progressing outboard to the wing tip fracture. The pitot tube was bent left and up, and was embedded in the wing's leading edge. The left main fuel tank was broken open underneath. The smell of auto fuel was prevalent around the accident site. Approximately 5 gallons of fuel were recovered from the airplane's left wing tank. The plexiglass cover protecting the landing and taxi lights was crushed inward. The landing light was broken inward. The taxi light remained intact. The left wing tip was broken off along the rivet line. The left aileron showed minor upward buckling. The left flap was positioned down 30 degrees. The inboard 14 inches of the left flap was bent aft and down.

The right wing was crushed along the entire span of the leading edge, from the leading edge aft to the main spar and down. The crush line displayed on the right wing showed an 85-degree angle to the airplane's longitudinal axis. The leading edge was bent upward and aft approximately 35 degrees, beginning 6 feet outward from the wing root and progressing outboard to the wing tip fracture. The right main fuel tank was broken open underneath. The smell of auto fuel was prevalent around the area. The right wing tip was broken off at the rivet line and broken open at the forward edge. The left aileron was bent upward three feet outward from the inboard edge. The left flap was positioned up and showed minor bending and skin wrinkling.

The airplane and its components were removed to Stensrud Aviation, Waseca, Minnesota, and examined on September 24, 1996, at 0900 cdt. Examination of the engine revealed that the number two cylinder exhaust valve was stuck open. Removal and examination of the number two cylinder exhaust valve showed material deposits on the stem. Material deposits were also found on the number two cylinder head.

The stall warning horn was removed and connected to a 12-volt power source. The horn functioned properly.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy of the pilot was conducted by the Hennepin County, Minnesota, Deputy Chief Medical Examiner, on September 23, 1996, at Saint Paul, Minnesota. The autopsy determined the cause of death to be "multiple blunt-force injuries due to single-engine plane crash."

The results of FAA toxicology testing of specimens from the pilot were negative for all tests conducted.

ADDITIONAL INFORMATION

Parties to the investigation were the Federal Aviation Administration Flight Standards District Office, Minneapolis, Minnesota, The Cessna Aircraft Company, Wichita, Kansas, and Teledyne Continental Motors, Mobile, Alabama.

All wreckage was released and returned to Stensrud Aviation, Waseca, Minnesota.

NTSB Probable Cause

a loss of power due to the engine's #2 cylinder exhaust valve stuck open, and the pilot's failure to maintain airspeed.