NTSB Factual Report

HISTORY OF FLIGHT

On May 11, 1996, about 1244 eastern daylight time, a WSK PZL Mielec M18A, N2065K, registered to and operated by the State of North Carolina Division of Forest Services as flight bomber 4, crashed into a wheat field shortly after takeoff from the Kinston Regional Jetport at Stallings Field, Kinston, North Carolina. Visual meteorological conditions prevailed at the time and no flight plan was filed for the public-use flight. The airplane was destroyed by impact and a postcrash fire and the commercial-rated pilot, the sole occupant, was fatally injured. The flight originated about 2 minutes earlier.

The individual who loaded the fire retardant into the hopper tank of the airplane reported that while loading the retardant, the pilot had the engine operating at an above idle position. He motioned for the pilot to reduce the rpm, and the pilot complied. Then during the loading, he had to ask the pilot how much [retardant] he wanted, to which the pilot responded 550 or 500 [gallons], whatever. The loader stated that when he observed the retardant go out of the sight glass which is 550 gallons, he turned the pump off but not before he observed foam come out of the other side of the airplane. The individual also stated that the pilot did not appear to be himself because he had to ask the pilot what quantity of retardant he wanted.

Review of Air Traffic Control communications revealed that the time interval between the pilot acknowledging the taxi clearance and takeoff clearance was determined to be about 4 minutes 33 seconds. About 2 minutes 38 seconds after the pilot acknowledged the takeoff clearance he advised the controller that, "we like to dump this load return back for uh landing." The controller inquired if the pilot was experiencing a problem, but there was only a reply giving the partial call sign of the flight.

According to several witnesses, the airplane was observed in a climb attitude with one witness reporting observing what appeared to be a fire from the right side of the airplane forward of the cockpit. One witness reported seeing black smoke coming from the airplane. The engine was heard to surge and a small amount of what appeared to be white smoke was observed briefly trailing the airplane by one of the witnesses. Release of the fire retardant was observed while the airplane was banked to the left followed by a nearly simultaneous pitch-up of the airplane. Several witness reported that the airplane then pitched nose down and impacted the ground in the wheat field followed shortly thereafter by fire and an explosion.

PERSONNEL INFORMATION

Information pertaining to the pilot is contained on page 3 of the Factual Report-Aviation. Review of the pilot's training records revealed that in March of 1995, he was tested pertaining to the accident airplane's systems. In March of 1996, he received instruction in the accident make and model airplane on 2 separate flights on 2 days about 12 days apart. The total flight time for both flights was documented to be 2.2 hours and a total of four drops were made. The last flight logged in the accident make and model was his last training flight which occurred on March 13, 1996. Further review of his file from February 21 to April 27, 1996, revealed he had flown other airplanes specifically, an S-2, which is also used for fire fighting. During that period he logged 16.2 hours in that make and model with an associated 12 drops. According to the operator of the S-2 airplanes, the design gross weight is 6,600 pounds.

AIRCRAFT INFORMATION

Information pertaining to the airplane is contained on page 2 of the Factual Report-Aviation and Supplements A and B. On March 16, 1996, the airplane operator received FAA approval to operate the airplane to a maximum gross weight of 12, 499.9 pounds. The approval was based on a FAA observed visual flight test and current aircraft information. According to the operator, postcrash the FAA revoked the overweight approval.

METEOROLOGICAL INFORMATION

Visual meteorological conditions prevailed at the time. Additional weather information may be obtained on page 4 of the Factual-Report Aviation.

COMMUNICATIONS

The pilot was in contact with the Kinston Airport Air Traffic Control Tower at the time of the accident.

WRECKAGE AND IMPACT INFORMATION

Examination of the crash site which was located about 1 nautical mile south-southeast of the airport revealed that the airplane impacted an open wheat field while on a magnetic heading of about 060 degrees. The airplane was observed to be upright with three of the four propeller blades separated and nearly completely buried in the ground about 2 feet aft of the wreckage. Molten aluminum was observed on the ground surface near the empennage but heat damage to the wheat crop in that area was not noted. The left main landing gear was collapsed and the tailwheel was separated. All flight control surfaces, wings, and horizontal stabilizers were attached or partially attached to the airframe; the right horizontal stabilizer was displaced downward just outboard of the lower support strut. Soot was not observed on either the left or right horizontal stabilizers or elevators. Examination of the rudder, elevator, and aileron flight controls revealed no evidence of preimpact failure or malfunction. Both wing fuel tanks were fire damaged as was the cockpit, hopper section, and engine area. Fire damage was noted to the wheat crop slightly forward of the wings which were fire damaged and also slightly forward of the engine which was also fire damaged. The flaps were determined to be extended 3.5 degrees and examination of the cockpit revealed the hand operated primer was unlocked and positioned to the "cylinder" position. Also, the electrically activated stall warning system was in the "off" position.

The engine was partially attached to the airframe and was displaced to the right at about a 45-degree angle. The cylinder heads from the Nos. 5 and 6 cylinders were observed to be separated and were found in the vicinity of the engine. Examination of the No. 6 cylinder revealed the exhaust valve keepers were dislodged and were found past the cone shaped retainer. The remaining propeller blade was burned to within several inches of the hub and was displaced forward. Examination of the separated propeller blades revealed evidence of torsional twisting. The fire door was determined to be open. Examination of the right side of the airplane in the hopper tank area revealed aluminum splatter on the aft side of the firewall in the area adjacent to the fuel shutoff valve which was destroyed by fire. Visual examination of the electrical cables in that area revealed no evidence of electrical arching. The engine was removed for further examination.

Examination of the engine revealed crankshaft, master rod, and valve train continuity. The gear alignment of the crankshaft and cam ring was confirmed as well as continuity to the supercharger. The connecting rods were found to be intact with no evidence of being bent. The magnetos were determined to be tight on the accessory case but magneto to engine timing was not determined. The magnetos were heat damaged but rotation by hand revealed both operated normally. Examination of the spark plugs revealed evidence of oil contamination. Additionally, the cylinder heads from the Nos. 5 and 6 cylinders were metallurgically examined with no evidence of preimpact failure or malfunction. Witness marks from the keepers from the No. 6 cylinder exhaust valve in the normally installed position were observed. Examination of the No. 5 cylinder head and one of the separated propeller blades revealed evidence of contact. The throttle at the carburetor was determined to be fully open and there was no blockage of the air inlet at the carburetor. The inlet screen of the carburetor was examined with no evidence of contaminants noted. The induction pipes were determined to be burned away and the drive for the engine-driven fuel pump was intact. The engine-driven fuel pump was removed for further examination. (See tests and research section of this report).

MEDICAL AND PATHOLOGICAL

A postmortem examination of the pilot was performed by F.N. Hellman, M.D., Forensic Pathologist, Greenville, North Carolina. The cause of death was listed as smoke inhalation, thermal burns and blunt force injuries. Toxicological analysis was performed by the Office of the Chief Medical Examiner, Chapel Hill, North Carolina. The results were negative for ethanol, and less than 5 percent saturation carbon monoxide was detected. Toxicological analysis was also performed by the FAA Accident and Research Laboratory. The results were negative for carbon monoxide, cyanide, and volatiles. Diphenhydramine and Trimethoprim were detected in the blood and urine. The pilot was prescribed Septra DS which contains an antibiotic containing trimethoprim, for prostatitis.

According to the Physicians' Desk Reference (PDR) for non-prescription drugs revealed that diphenhydramine hydrochloride is found in decongestant tablets. The warning for the tablets indicates that marked drowsiness may occur and to use caution when driving a motor vehicle.

TESTS AND RESEARCH

Examination of the engine-driven fuel pump revealed no evidence of preimpact failure or malfunction.

Simulation of the loading of the fire retardant was performed by the individuals who loaded the accident airplane. The amount of fire retardant loaded into the accident airplane was determined to be 586 gallons which was based at the point when a layer of foam that was 2-4 inches in height would contact the hopper tank vent. According to the operator of the airplane, the hopper vent of the accident airplane had a known history of not fully closing.

Weight and balance calculations were performed based on the current airplane weight and balance (6,365.3 pounds), the weight of the pilot based on his last medical (180.0 pounds), full fuel capacity before engine start (1,128 pounds usable fuel), and 586 gallons of retardant at a weight of 9.1279 pounds per gallon (5,348.94 pounds). The airplane was calculated to weigh 13,022.25 pounds at the time of engine start. According to the type certificate data sheet the maximum gross weight is 9,260 pounds. As previously mentioned, the FAA approved operation of the airplane in an overgross weight condition to a maximum weight of 12,499.9 pounds but revoked the approval postcrash.

Review of excerpts from the aircraft flight manual revealed that during release of the fire retardant, the altitude will increase from 66-100 feet and the airspeed will decrease 6-12 miles per hour. The flight manual also indicates to counteract the rapid pitching up movement of the airplane to move the control stick forward 3-4 inches from its initial position.

Engine operation at takeoff power and at idle power duplicating the as found position of the primer handle was performed postcrash which revealed no effect on engine performance.

ADDITIONAL DATA/INFORMATION

The accepted procedure by the operator was to start the engine of each one of their aircraft in the morning until normal operating temperatures are attained then the engine is shut down until called for a mission. Before the flight departed the pilot reportedly did not rotate the propeller to clear the lower cylinders of oil accumulation which is required by the flight manual. Additionally, according to the chief pilot, if the dump gate does not close properly, a thin trail of white retardant is visible trailing the airplane.

The wreckage minus the retained engine was released to Harry B. Sumner, Chief Pilot, on May 13, 1996. The retained engine was also released to Mr. Sumner on July 24, 1997.

NTSB Probable Cause

a cracked/fractured #5 cylinder and subsequent failure/jamming of the #5 exhaust valve, which resulted in a partial loss of engine power; and failure of the pilot to maintain adequate airspeed, which resulted in a stall and collision with the terrain. Factors related to the accident were: the excessive gross weight of the airplane, the pilot's lack of familiarity with the airplane, and pilot impairment from use of an over-the-counter medication with sedative side effects.