FTW96FA183

The airplane was on a two-leg cross-country instructional flight. Shortly after taking off on the second leg, an FAA FSS facility informed the pilots of a flight precaution for moderate to occasionally severe turbulence from the surface to 14,000 feet. After about 50 minutes of flight, the airplane crashed. There was evidence that the airplane crashed during an uncontrolled descent. Just before impact, a witness saw the airplane flying 'just above the tree tops' approximately one mile from the accident site. Witnesses near the crash site reported seeing 'white smoke and orange flame' coming from the airplane before impact. Examination of the wreckage revealed that incorrect exhaust system clamps had been used to attach the muffler to the right (#1 and #3) exhaust stacks. The clamps were identified as automotive types. There was evidence of an exhaust stack separation from the muffler and that exhaust gasses had entered the area around the carburetor fuel supply line. There also was evidence that an in-flight fire had burned through the lower left portion of the engine cowling, and an adjacent hole had been burned through the engine fire wall to the cabin area.

History of flight

On April 27, 1996, at 1420 central daylight time, a Piper PA-28-151, N7845C, was destroyed when it impacted the ground in an uncontrolled descent following an in-flight fire near Vera, Oklahoma. The flight instructor, two student pilots, and one passenger were all fatally injured. The aircraft was registered to a private owner and operated by Kiamana Aviation under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the cross country instructional flight that originated from Siloam Springs, Arkansas, approximately 50 minutes before the accident. A VFR flight plan had been filed.

The owner of the flight school reported to the investigator-in-charge that the airplane left Ponca City, Oklahoma, at approximately 0930 that morning for an estimated 1 hour and 20 minute flight to Siloam Springs, Arkansas. The owner further reported that the school's policy was to fully fuel all aircraft as soon as they land; therefore, he believes that "this airplane took off fully fueled."

According to witnesses in Siloam Springs, the airplane was on the ground for approximately 3 hours while the 4 occupants attended a regional "Spring Fly In." Records at the Smith Field FBO, near Siloam Springs, Arkansas, indicate that no fuel was purchased for the airplane on that date. A weather report was obtained and a flight plan was filed with Jonesboro FSS for the return trip to Ponca City.

The airplane departed Siloam Springs at 1330, climbed to 4,500 feet MSL, and the pilot called Jonesboro FSS to activate the flight plan. The pilot reported to Jonesboro FSS that they were presently in light to moderate turbulence and inquired if the weather at Ponca City was "still clear." Jonesboro FSS replied that Ponca City was 5,000 feet scattered, 15,000 feet overcast, 12 miles visibility, and the wind was 180 degrees for 13 knots.

The airplane was next seen near Vera, Oklahoma, by a witness, who works in the aviation industry. He reported that "I observed a small white aircraft with blue markings flying at a low altitude. Since I work in the aviation industry, I was somewhat startled to notice it was flying just above the tree tops." He observed the airplane for approximately "5 to 10 seconds before it disappeared beyond the trees, about 3/4 of a mile from him. I would estimate this to be about 1 mile from the site of the crash."

The investigator-in-charge queried the Tulsa approach control radar facility for a possible radar track of the accident airplane. They reported that they could not locate a transponder signal or a primary return signal that could be correlated with the airplane. Further questioning of the radar facility revealed that their equipment could not see below 500 feet AGL along the projected flight path of the accident airplane.

Witnesses near the accident site "heard a small engine plane" and their attention was drawn to it because "the engine tone changed pitch." They observed the airplane at very low altitude "banking side to side with white smoke trailing from it." The witnesses further stated that they saw the white smoke turn to black smoke and one witness saw "orange flame coming out the left side of the engine compartment." The aircraft was observed to roll left and impact the ground inverted, in a nearly vertical orientation.

Personnel information

The flight school reported to the investigator-in-charge that the instructor pilot had approximately 400 hours of flight time. FAA records indicate that the instructor pilot started his flying career by obtaining his student certificate on April 1, 1994, and he became a flight instructor on September 23, 1995.

The student pilot, who was in the left seat at the time of the accident, had received her student certificate 25 days prior to the accident. It was estimated from interviews with her friends that she had received approximately 11 hours of flight training prior to the accident. The second student pilot, who flew the first leg of the instructional cross country flight from Ponca City to Siloam Springs, had received his student certificate from the FAA on February 16, 1996.

Aircraft information

The accident airplane was built in 1975 and had accrued approximately 7,049 hours of flying time. The last annual inspection was performed 3 days before the accident at a tachometer time of 7,039.72 hours. The inspection checklist for the most recent annual inspection showed that the muffler and attachment clamps had been inspected. A top overhaul of the engine was performed on November 27, 1995, at a tachometer reading of 6,951.03. The engine's front exhaust muffler was replaced during the previous annual inspection on February 14, 1995, at a tachometer time of 6,781.21 hours. See attached copies of pertinent maintenance records.

The muffler system consists of two parallel mufflers with a heat exchanger shroud around them (see attached diagram). The right side of the muffler has two intake ports protruding from it where the number one exhaust stack and the number three exhaust stack are respectively inserted. The intake ports and the exhaust stacks each have a hole in them for attachment and alignment of the exhaust stacks to the muffler. A special clamp with a pin in it (see photo No.7) was designed to fit around the muffler intake port in such a manner as to allow the pin to penetrate the hole in the muffler intake port and the inserted exhaust stack. This securely attaches the muffler to the exhaust stacks and does not allow for any movement between them.

The left side of the muffler also has protruding intake ports for the purpose of receiving the number two exhaust stack and the number four exhaust stack respectively. The only difference is that there are no holes provided for securing them together and no clamps are needed for their attachment. They are designed to help hold the muffler in place and allow for expansion and contraction (see photo No.17).

Meteorological information

The student pilot called for weather at 0830 and was informed that there was an Airmet over eastern Oklahoma for occasional moderate turbulence below 6,000 feet. The student pilot called again for weather at approximately 1300 and was told that a Flight Precaution had been issued for the same region for occasional moderate turbulence from the surface to 15,000 feet. The pilot was informed shortly after takeoff from Siloam Springs, Arkansas, by Jonesboro FSS that the Flight Precaution had been updated to include moderate to occasionally severe turbulence from the surface to 14,000 feet.

Wreckage and impact information

The airplane was found inverted, in an open field, with the nose approximately 70 degrees below the horizon. Both propeller blades remained attached to the crankshaft. One blade was bent back approximately 45 degrees from the hub, the other was bent back approximately 20 degrees and exhibited torsional twisting. Both blades had chordwise scratching. The engine was buried in the ground up to the level of the accessory case. The rear of the engine was covered by the fire wall and the remains of the instrument panel. The majority of the airplane was severely burned except for the right wing which displayed longitudinal crushing across the entire span. All structural components were accounted for, but, due to extent of the impact damage and post-crash fire, it was not possible to determine control continuity. The engine crankshaft was rotated and continuity to the accessory gears was confirmed.

The cabin entry door was found separated from the fuselage and not collocated with associated aircraft structural components. The cabin doors' upper latch was found in the unlatched position. Normal operation of this latch requires a positive engagement to secure it in the latched position and a positive disengagement to move it to the unlatched position.

One piece of wreckage was identified as t