PORTER, TX, USA
N8488T
CESSNA 182C
DURING TAXI, WITNESSES OBSERVED BLACK SMOKE COMING FROM THE EXHAUST. THEY ALSO SAID THE ENGINE STARTED TO LOSE POWER DURING THE TAKEOFF GROUND RUN. THE AIRPLANE LIFTED OFF THE RUNWAY ABOUT MIDFIELD; THE ENGINE WAS STILL RUNNING ROUGH & MISSING, AND THE AIRPLANE WAS NOT CLIMBING WELL. THEY OBSERVED THE LANDING GEAR AND LOWER FUSELAGE STRIKE THE TREES. METALLURGICAL EXAMINATION REVEALED THAT THE RIGHT CONE BAFFLE OF THE MUFFLER SEPARATED DUE TO OXIDATION. FRACTURING MODE WAS MOST PROBABLY PROGRESSIVE IN NATURE, AND THE CONE HAD SEPARATED AT SOME POINT PRIOR. HOWEVER, THE MODE OF FRACTURING COULD NOT BE DETERMINED DUE TO THE OXIDATION. THE END PLATES AND INLET TUBES OF THE MUFFLER EXHIBITED DEFORMATION AND THEY DID NOT CONFORM TO THE MANUFACTURER'S SPECIFICATION. EXAMINATION OF THE ENGINE AND PROPELLER NOT DESTROYED BY THE POST CRASH FIRE DID NOT REVEAL ANY ADDITIONAL ANOMALIES.
HISTORY OF FLIGHT: On September 4, 1993, at 0744 central daylight time, a Cessna 182C, N8488T, was destroyed near Porter, Texas, during impact with trees and terrain following a loss of engine power during the takeoff. The private pilot and two passengers sustained fatal injuries. A third passenger received serious injuries. Visual meteorological conditions prevailed for the personal cross country flight with a planned destination of Mountain Home, Arkansas. A flight instructor, who had previously flown the airplane, stated to the investigator-in-charge during a telephone interview, that over the last month black smoke had been observed several times coming from the exhaust during takeoff or landing. He further said that oil was found in the exhaust stack; however, examination by mechanics did not reveal any discrepancies. Several witnesses reported to a Federal Aviation Administration inspector that they had observed black smoke coming from the exhaust earlier in the year. During interviews conducted by the investigator-in-charge, witnesses, said that black smoke was observed coming from the exhaust as the airplane taxied for takeoff. They observed that following the runup, the pilot initiated the takeoff roll to the north. During the takeoff ground run, they described the airplane engine as missing and expected the pilot to abort the takeoff. They observed the airplane lift off the runway at about midfield, still missing, running rough, and not climbing. One witness stated a "reduced power output" and described the airplane as "flying level with the nose up attitude (approximately 15 degrees) at slow airspeed (approximately 60 mph) and 40 to 50 feet above the runway." Before reaching the trees at the north end of the runway, the airplane "appeared to mush up" over the 60 foot trees, not climbing. Witnesses saw and heard the airplane impact trees approximately 300 yards beyond the departure end of the runway. Post impact fire engulfed the wreckage. PERSONNEL INFORMATION: During interviews conducted by the investigator-in-charge with acquaintances of the pilot it was revealed that the pilot had performed numerous takeoff and landings in N8488T. Pilot logbooks were believed to have been destroyed by the post crash fire. During the telephone interview, conducted by the investigator-in- charge, the passenger stated that she had flown with the pilot numerous times in various airplanes, twice during dual instruction in N8488T. She further stated that the pilot and she had weighed the luggage the evening before the flight and the airplane was "definitely not over loaded." She further stated that the pilot conducted a preflight of the airplane prior to the departure. She reported the runup and takeoff as "normal" until she looked "up, saw the tips of the trees, and heard the tree limbs scraping the airplane." AIRCRAFT INFORMATION: Aircraft maintenance records reviewed by the investigator-in- charge indicated that a new Nicrocraft muffler was installed on June 26, 1991 at a tachometer time of 2640.1 hours. The records further indicated that on February 19, 1993, the muffler was inspected during a 100 hour inspection at a tachometer time of 2832.6 hours. The owner reported 39 hours since the inspection for a total of 231.5 hours since original installation of the muffler. Manufacturer records reviewed by Federal Aviation Administration inspectors and the investigator-in-charge indicated that muffler p/n CEM0001, s/n 0-4657 completed the final manufacturer inspection on November 19, 1990, and was shipped from the factory on June 20, 1991. A muffler warranty card (copy enclosed) returned to the manufacturer stated "NO" to the question "Did the part fit properly?" WRECKAGE AND IMPACT INFORMATION: Tree limbs one foot in diameter were located at the base of trees with limbs broken 90 feet above the ground. Pieces of green lens were located 40 feet north of the base of the trees. Trees in the wreckage distribution area reached approximately two feet in diameter. Several tree limbs showed scrapes and gouges. The airplane came to rest on a measured magnetic heading of 060 degrees 138 feet from the initial trees with broken limbs. The right wing, fuselage, cabin, cockpit area, and engine accessories were destroyed by fire. The outboard portion of the left wing and the empennage were found inverted. One metal carburetor float was found forward of the firewall. One propeller blade was flat in the hub. MEDICAL AND PATHOLOGICAL INFORMATION: The autopsy was performed by the Office of the Medical Examiner of Harris County, Houston, Texas. Toxicological findings were negative. TESTS AND RESEARCH: The propeller and blades were examined (see enclosed report) on September 22, 1993, with no indications of propeller failure prior to impact. The engine and accessories not destroyed by the fire were examined (see enclosed report) on September 22, 1993, at Mobil, Alabama. The muffler right baffle cone was found separated from the inlet tube at the end plate subassembly. Portions of the muffler were cut away to examine the end plates, inlet tube and the cones. The fractured surface on both the right cone and the right inlet tube was distorted. The exhaust pipe exit from the muffler exhibited polishing patterns at the outlet. The muffler components were forwarded to the NTSB laboratory for further examination. Manufacturer examination of the muffler (enclosed report) on March 14, 1994, and March 24, 1994, indicated that the muffler did not meet the manufacturer specifications. They agreed on the oxidation separation of the cone baffle and the deformation of the end plate and inlet tube. The pieces exhibited heat and mechanical distortion. Calculations by the manufacturer indicated a maximum possible blockage of the exhaust overboard by a separated baffle would be 20 percent. Materials Laboratory NTSB Metallurgist (see enclosed report) examined the muffler and identified the muffler by a data plate as a Nicrocraft p/n CEM0001, s/n 0-4657, manufactured by Wall Colmonoy Corporation of Oklahoma City, Oklahoma. Examinations showed that the right cone was separated from the inlet along a circumferential fracture through the cone inlet tube that connects the cone to the muffler end plate. The fracture cone and inlet tube exhibited deformation. Optical examinations revealed heavy high temperature oxidation and combustion gas products on both of the fractured surfaces. Scanning electron microscopy (SEM) examinations of the fractured surfaces showed that all of the fracture features had been obliterated by the oxidation. Metallurgical examination showed that the cone and inlet contained a circumferential braze line with heavy oxidation on all surfaces. Measurements showed that the fractured cone header was between 0.021 and 0.023 inches thick in the area of the fracture and that it was between 0.025 and 0.028 inches in thickness near the inlet end. A review of the Federal Aviation Administration issued Supplemental Type Certificate (STC) for the CEM0001 revealed the was originally issued on August 7, 1975, and was revised on April 22, 1976. Copies of the STC are included as a part of this report. ADDITIONAL DATA: The airplane was released to the owner's representative following the investigation.
PARTIAL LOSS OF ENGINE POWER FOR UNDETERMINED REASONS. FACTORS IN THE ACCIDENT WHICH MAY HAVE CONTRIBUTED WERE THE DISTORTED AND SEPARATED MUFFLER COMPONENTS RESULTING FROM IMPROPER MAINTENANCE BY AN UNKNOWN PERSON.
Source: NTSB Aviation Accident Database
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