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On November 28, 2007, about 1530 central standard time, a single-engine Cessna 172N airplane, N6555D, was substantially damage when it collided with terrain while maneuvering near Marlow, Oklahoma. The certified flight instructor (CFI) and passenger sustained fatal injuries. The airplane was registered to a private individual and was being operated by the pilot. Visual meteorological conditions prevailed and no flight plan was filed for the 14 Code of Federal Regulations Part 91 personal flight. The local flight originated from the Lawton-Fort Sill Regional Airport (LAW), near Lawton, Oklahoma, around 1515.
Three eyewitnesses reported seeing the airplane shortly before impact.
Two witnesses were working in a creek bed approximately a quarter mile west of the accident site when they observed the airplane. Both witnesses were interviewed separately and given a small representation of the airplane and asked to describe what they saw.
The first witness reported hearing an "engine sound that wasn't right." He then observed the airplane flying in a southerly direction at an altitude less the 1,000 feet above ground level (agl). The witness motioned and described an airplane that was in a level flight attitude, and then started to rock the wings from side to side, rolled right, became inverted, with the nose 90 degrees to the terrain. The witness stated that he thought the pilot was attempting to do a loop as it looked as if he was trying to pull out of the dive. The airplane then disappeared from view. When asked to describe the engine noise he heard, the witness could not describe any particular sounds, but described it as "unusual." The witness further reported that the wind was from the northwest.
The second witness stated he heard the engine "cut out" more than once. The witness reported observing the airplane flying straight down before it disappeared out of his view. He further reported the wind was out of the northwest at approximately 25 miles per hour.
The third witness reported that the accident airplane had flown over the house owned by the pilot's parents shortly before the accident. This house was located about two miles northeast of the accident site. The witness estimated the airplane’s altitude to be about 700 feet above ground level.
The pilot held a certified flight instructor certificate with ratings for airplane single-engine land, multi-engine land, and instrument airplane. His last Federal Aviation Administration (FAA) second-class medical was issued on August 15, 2007, with no limitations.
No personal flight records were located for the pilot and the aeronautical experience listed in this report was obtained from a review of the airmen FAA records on file in the Airman and Medical Records Center located in Oklahoma City. These records indicated that as of a medical examination on August 15, 2007, the pilot reported a total time of 600 flight hours with 150 flight hours logged in the last 6 months.
The 1979-model Cessna 172N, serial number 17272863, was a high wing, semi-monocoque airplane, with a fixed landing gear, and was configured for four occupants. The airplane was powered by a direct drive, horizontally opposed, air-cooled, normally aspirated, carbureted, four-cylinder engine. The engine was a Lycoming O-320 H2AD, serial number L8322-76T, rated at 160 horsepower at 2,700 rpm, and was driving a McCauley two-bladed fixed pitch propeller.
According to the airframe logbook, the airplane's most recent 100-hour inspection was completed on October 10, 2007, with an airframe total time of 12,282.6 hours. At the time of the accident, the airframe had accumulated approximately 12,314.2 hours and 31.6 hours since the last inspection.
The engine logbook revealed that the engine had been inspected in accordance with a 100-hour inspection on October 10, 2007. At the time of the accident the engine had accumulated approximately 1,721 hours since major overhaul.
Fueling records at LaSill Aviation, located at LAW, established that the airplane was fueled on November 28, 2007, with the addition of 21.2 gallons of 100 low lead aviation fuel.
At 1553, the automated weather observing system at the Lawton-Fort Sill Regional Airport (LAW), located 35 miles west of the accident site, reported wind from 340 degrees at 20 gusting to 26 knots, 10 statute miles visibility, clear of clouds, temperature 57 degrees Fahrenheit, dew point 32 degrees Fahrenheit , and a barometric pressure setting of 30.11 inches of Mercury.
WRECKAGE AND IMPACT INFORMATION
On site documentation of the wreckage was conducted by investigators from the National Transportation Safety Board, the Federal Aviation Administration, and Cessna Aircraft Company. A representative from Lycoming Engines participated in the investigation upon recovery of the engine.
The wreckage was located in a flat wooded area. The initial impact point was the top branches of an oak tree. Broken tree limbs were found progressively lower to the ground, along the airplane’s flight path, on a magnetic heading of approximately 315-degrees. The debris field encompassed an area approximately 125 feet long by approximately 30 feet wide, and ended at the main wreckage, which had come to rest in an upright position on a heading of about 330-degrees. The main wreckage consisted of the fuselage, empennage, engine, propeller, and the inboard 12 feet of the right wing. The left wing and remainder of the right wing was scattered along the wreckage path. All major components of the airplane were accounted for at the site.
An examination of the wreckage revealed that the flaps were in the retracted position at the time of impact. Control continuity was established to all flight controls. The fuel tank selector valve was found in the "Both" position. The elevator trim tab was found in the 15-degrees tab up position. Both the left and right fuel tanks were found breached. The right fuel tank and the fuel tank selector valve contained a blue liquid consistent with 100 low lead aviation fuel.
The propeller remained attached to the engine crankshaft flange. One blade was bent aft approximately 30-degrees and its leading edge was twisted aft. The blade tip was curled forward. The other blade was bent aft about 90-degrees near mid-span. The leading edge near the tip exhibited an estimated one half inch by one quarter inch deep gouge. Both blades exhibited chordwise scratching and leading edge polishing.
The engine was removed from the airframe and examined. The propeller, valve covers, and upper spark plugs were removed. The engine was rotated via the propeller flange. Crankshaft and valve train continuity were observed throughout the engine with the exception of the number three cylinder rocker arms. The number three cylinder head had sustained impact damage and both pushrod tubes were flattened and impinged on the pushrods. Thumb compression was obtained in all cylinders.
An unmeasured amount of oil was observed in the oil sump. No visible contaminates were noted in the oil or oil suction screen. The dual magneto was removed and rotated by hand. Spark was observed to each spark plug lead. The carburetor air intake was found to be unobstructed. The starter housing displayed rotational gouging from impact with the starter ring gear support.
Examination of the airframe disclosed no anomalies that would have prevented normal system operation and no abnormalities were noted with the engine that would have precluded the engine from producing power.
MEDICAL AND PATHOLOGICAL INFORMATION
The Office of the Medical Examiner, located in Oklahoma City, Oklahoma, performed an autopsy on the pilot on November 29, 2007. The cause of death was listed as "Multiple Blunt Force Trauma."
The FAA, Toxicology Accident Research Laboratory, located in Oklahoma City, Oklahoma, conducted toxicological testing on the pilot. The results of the testing were negative for carbon monoxide, cyanide, ethanol, and tested drugs.