BRYAN, TX, USA
N4803D
Cessna 182A
Witnesses reported that the single-engine airplane's takeoff and climb appeared to be normal. As the airplane climbed through 400 feet, a puff of black smoke was observed emanating from the right side of the engine compartment. The airplane nosed up slightly, then nosed down turning about 360 degrees before descending rapidly from view. One witness heard the engine start missing before the airplane turned and descended. Continuity was established to all flight controls. Examination of the engine revealed that the #6 cylinder head separated from its cylinder barrel as a result of fatigue cracking originating in the cylinder head threads. When the engine was overhauled about 353.86 hours prior to the accident, 6 Nu-chromed overhauled cylinders were installed. It could not be determined how many hours the cylinders had accumulated nor how many times they had been overhauled. There is no requirement to track cylinder hours or overhaul occurrences.
HISTORY OF FLIGHT On September 18, 1999, at 1859 central daylight time, a Cessna 182A airplane, N4803D, was destroyed when it impacted terrain following a loss of engine power and a loss of control during takeoff from the Coulter Field Airport near Bryan, Texas. The airplane was registered to SMC Institute A Close Corporation of Wilmington, Delaware, and operated by Ags Over Texas of Bryan, Texas. The commercial pilot and four parachutists were fatally injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 parachute activity flight. The flight was originating at the time of the accident. Witnesses reported to the NTSB investigator-in-charge (IIC) that the airplane departed runway 14 and the takeoff and climb appeared to be normal. As the airplane was climbing through approximately 400 feet, a witness observed a puff of black smoke emanating from the right side of the engine compartment. The airplane nosed up slightly and then nosed down descending rapidly. A witness, sitting outside in his yard, heard the "engine start missing." The airplane turned toward the runway, and "I thought it was going back to Coulter Field Airport. A few seconds later I saw it go straight down." Another witness (dove hunter), located about 1/2 to 3/4 mile from the accident site, observed the airplane heading east at about 300-400 feet agl. He stated that "the aircraft appeared to stall. The right wing dropped quickly and the aircraft spun in, nose down, spin[ning] to the right, making one complete revolution before impacting the ground." Subsequently, black smoke was observed in the area where the airplane descended from view. PERSONNEL INFORMATION According to FAA records, the pilot was issued a private pilot certificate on January 4, 1997, and on April 15, 1998, he was issued an instrument rating. On July 13, 1998, he obtained a commercial pilot certificate with an airplane single-engine land rating. On December 2, 1998, he was issued a multi-engine land rating, which also sufficed as a biennial flight review. The pilot held a first class medical certificate, which was issued September 10, 1998. A review of the pilot's flight logbook revealed that on July 14, 1998, he received his first introductory flight for jump operations, and on July 18, 1998, he completed the jump operations training. The logbook showed that the pilot's first flight as pilot-in-command for jump operations was on July 18, 1998. The logbook also revealed that as of September 15, 1999, the pilot had logged a total flight time of 810.2 hours, of which 341.0 hours were logged in the same make and model as the accident aircraft. The pilot had logged 294.9 hours in jump operations. AIRCRAFT INFORMATION The 1956-model Cessna was a high-wing, single-engine airplane, which had fixed tricycle landing gear. The airplane was equipped with a Continental O-470-L engine rated at 230-horsepower, and was modified to drop skydivers. Modifications included the removal of the right control wheel, and all seats were removed except for the left front. A jump seat (solid plate backrest) was installed against the instrument panel next to the pilot. A jump door, jump light, droop wing tips, and a jump step were also installed. The airplane had been fueled with 14 gallons of 100LL aviation gasoline, two flights prior to the accident. One flight was to drop parachutists and the other was a "short" flight to locate a parachutist that landed off the airport. The pilot had flown the airplane several times earlier in the day prior to the accident flight. The Ags Over Texas operations officer suggested to the NTSB IIC that the student static line parachutist would sit next to the pilot. One parachutist would sit behind the pilot, and the tandem parachutist would sit next to that parachutist near the door. The other parachutist would sit aft of the middle two parachutist. This seating arrangement could not be confirmed, and the weight of the static line parachutist was not obtained, therefore, an accurate weight and balance could not be determined. However, using the suggested seating arrangement and 120 pounds for the static line parachutist, the NTSB IIC, using the aircraft owner's manual, calculated that the airplane would be within weight and balance limits. A review of the aircraft's maintenance records revealed that the engine was overhauled on October 25, 1997, at a total aircraft time of 6,572.41 hours and engine total time of 4,464.29 hours. During the engine overhaul, 6 Nu-chromed overhauled cylinders were installed. The aircraft underwent its last annual inspection on October 15, 1998. The last 100-hour inspection was completed on January 28, 1999, 248.84 hours since engine overhaul, at which time the engine received its last compression check before the accident. The compression check did not reveal any anomalies in cylinder head compression. As of September 12, 1999, the engine had accumulated 353.76 hours since its overhaul. According to the facility that overhauled the cylinders, the cylinder heads were not removed from the cylinder barrels during overhaul. Each cylinder was Nu-chromed and the head was then ultrasonically inspected for cracks. It could not be determined how many hours the cylinders had accumulated nor how many times the cylinders had been overhauled, nor is it required to track cylinder time or overhaul periods. WRECKAGE IMPACT INFORMATION The accident site was located about 1/4 mile from the departure end of runway 14, at latitude 30 degrees 42.6 minutes north and longitude 096 degrees 19.6 minutes west. The airplane impacted the terrain on a magnetic heading of 115 degrees. The fuselage and engine came to rest upright on a heading of 120 degrees magnetic. The empennage was separated and adjacent to the fuselage but was facing 090 degrees. The fuselage and portions of the wings and control surfaces were consumed by fire. The empennage and outboard sections of the wings remained intact; however, they were fire damaged. Both wings tips appeared to be swept forward. Both wing leading edges were damaged, but neither wing leading edge was crushed aft. The right wing outboard of the fuel tank was curved upward, and its tip separated. The ailerons were found intact and remained attached to the wings. Both ailerons sustained impact and fire damage. The inboard sections of the left and right flaps were destroyed by fire. The flap actuator was found to be in a position consistent with a 40 degree extension of flaps. The left horizontal stabilizer was wedged between two small mesquite trees. The right elevator was deflected upward and the rudder was deflected to the right. Control continuity was confirmed to all flight control surfaces. A portion of the #6 cylinder head had separated from the barrel and was found laying next to the engine. The engine sustained some fire damage. The propeller was attached to the engine, and both propeller blades were secured in the propeller hub. One blade was bent aft under the engine, and its tip sustained fire damage. The other propeller blade had a slight forward bend and it had some chordwise scratching. The #6 cylinder head was sent to the NTSB Materials Laboratory in Washington, D.C., for further examination. The engine was removed and sent to the engine manufacturer's facility in Mobile, Alabama, for a detailed examination. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot at the Bexar County Forensic Science Center. The FAA Civil Aeromedical Institute toxicology laboratory detected 36.16 (mg/dl, mg/hg) of salicylate and 39.02 (mg/dl, mg/hg) of acetaminophen in the pilot's urine. TESTS AND RESEARCH On October 14, 1999, the Teledyne Continental O-470-L engine (serial number 67582-7-L) was examined at the Teledyne Continental Motors (TCM) facility at Mobile, Alabama, under the supervision of an NTSB representative. According to the manufacturer's representative, the engine exhibited heavy fire and impact damage. All internal components appeared "normal," except for the #6 cylinder. The #6 cylinder was separated where the cylinder head attaches to the cylinder barrel, and the fracture initiated on the exhaust side of the head at the first thread. According to the representative, the cylinder displayed "3-work order numbers" on the flange skirt. "The presence of these work order numbers would indicate this cylinder has many hours of time in service and has been worked on at least three times." The barrel portion of the #6 cylinder was sent to the NTSB Materials Laboratory in Washington, D.C., for further examination. Examination of the fractured cylinder at the NTSB Materials Laboratory revealed thick, black greasy deposits, consistent with combustion by-products, covered approximately 1/3 of the outboard fracture face on the side of the exhaust valve. A light ultrasonic cleaning in soapy water and then in acetone revealed that even after the cleaning, the fracture face still contained a crescent-shaped area of dark combustion deposits. The deepest portion of this darkly discolored region extended to a depth of approximately 0.45 inches from the inner diameter surface of the cylinder and was located about 30 degree offset from the exhaust valve. Examination of the inboard fracture face with the aid of a low power binocular microscope disclosed that a portion of the fracture was relatively smooth and contained multiple radial ratchet marks, indicative of fatigue cracking. The fatigue cracks originated at the root of threads located at the inner diameter surface of the cylinder head. The major origin of the fatigue cracking was located in the middle of the darkly discolored region on the fracture surface. The origin site coincided with the first outboard thread in the cylinder barrel and lay between the 5th and 6th cooling fins on the cylinder head. Magnified examination revealed no apparent defects at the root of the threads in the cylinder head. ADDITIONAL DATA The airframe was released to the owner on September 19, 1999, and the engine was released to the owner on March 15, 2000.
the pilot's failure to maintain aircraft control resulting in an inadvertent stall. A factor was the loss of engine power as a result of fatigue cracking and separation of the #6 cylinder head.
Source: NTSB Aviation Accident Database
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