WEST JORDAN, UT, USA
N61174
Commander 114TC
The pilot had washed the airplane and said he was going to 'take it around the pattern.' Shortly after takeoff, witnesses heard the engine backfire, heard a muffled explosion, and saw flames and smoke coming from the engine area. The engine was 'sputtering' as the airplane descended and collided with terrain in a residential area. The stainless steel shroud around the turbocharger was scorched and discolored. The main fuel line showed signs of high heat distress, but had not been breached except where it attached to the separated engine.. The exhaust pipe was separated from the turbocharger, and the clamp that held it in place was broken. According to the metallurgist's factual report, there was a brittle transverse fracture of the circumferential tensioning band near one of two resistance spot welds, and had propagated to both edges of the band. There were preexisting cracks at both of the spot welds. The airplane had accrued only 343.1 hours since manufacture.
HISTORY OF FLIGHT On July 18, 1998, approximately 1200 mountain daylight time, N61174, a Commander 114TC, was destroyed when it collided with terrain during an attempted forced landing about 1 mile southwest of Salt Lake City Municipal Airport No. 2, West Jordan, Utah. The commercial pilot, the sole occupant aboard, was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight being conducted under Title 14 CFR Part 91. The flight originated approximately 5 minutes before the accident. According to Lloyd Ramey, an employee of Hudson General (one of the fixed base operators at the airport), the pilot had washed the airplane at a wash rack on the north end of the airport, and told him he was going to "take it around the pattern" before putting it in the hangar. The airplane took off on runway 16. Numerous witnesses were interviewed by the West Jordan Police Department, and written statements were taken. One witness told police that as the airplane turned onto the crosswind leg, power was reduced. Another witness said he heard the engine backfire, then heard a muffled explosion. Numerous witnesses reported seeing flames and smoke coming from the bottom of the cowling. Another witness saw the airplane make a steep turn back towards the airport. Other witnesseses reported seeing the airplane "stall," "recover," and "porpoise." They said that as the airplane descended towards the ground, the engine "was sputtering" and the airplane was "rocking side to side." Witnesses told police the pilot maneuvered the airplane between two houses before striking a dirt embankment. They said it appeared the pilot intentionally struck this embankment to prevent the airplane from colliding with other houses nearby. [For additional information, see the 14 witness statements attached to the West Jordan Police Department report.] The airplane collided with terrain in a residential area about 0.7 mile southwest of the departure end of runway 16, at 4710 West 8170 South. CREW INFORMATION The pilot, Frank Lawrence Earl, age 29, was born on January 30, 1969. He held Commercial Pilot Certificate No. 529438850, dated March 7, 1995, with airplane single/multiengine land and instrument ratings, and Flight Instructor Certificate No. 529438850, dated January 23, 1998, with an airplane single engine rating. His second class Airman Medical Certificate, dated May 5, 1998, contained the restriction, "Holder shall wear correcting lenses while exercising the privileges of his/her airman certificate." Mr. Earl's most recent logbook was found in the wreckage and examined. The logbook contained entries from March 31, 1998, through July 16, 1998. His most recent biennial flight review was satisfied when he was issued his flight instructor certificate on January 23, 1998. A summary of Mr. Earl's flight times is attached as an exhibit to this report. Records submitted by IFR Flight Training School, Austin, Texas, indicated that between March 31 and April 1, 1998, Mr. Earl received 10.0 of ground instruction and 4.9 hours of flight instruction as part of his formal Commander 114TC checkout. AIRCRAFT INFORMATION N61174 (s/n 20014) was manufactured by the Commander Aircraft Company, Bethany, Oklahoma, and was issued an FAA Certificate of Airworthiness on May 21, 1997. It was equipped with a Textron Lycoming TIO-540-AG1A fuel injected engine (s/n L-9673-61A), rated at 270 horsepower; a Garrett turbocharger (s/n ZEN21723), and a McCauley 3-blade, all metal, constant speed propeller (s/n 952475). According to the maintenance records, the last airframe annual inspection and engine and propeller 100-hour inspections were accomplished on March 23, 1998, after 279.6 hours total time in service. The airplane holds a total of 90 gallons of fuel (45 gallons each wing tank). It was last serviced by Hudson General on July 16, 1998, when 59.0 gallons were added to fill the tanks to capacity. According to the "tach sheet" recovered from the wreckage, the airplane flew twice on July 17, 1998: 1.5 and 2.3 hours, respectively. The ending tachometer time was 343.1 hours. It was estimated that 30.0 gallons were aboard the airplane at the time of the accident. WRECKAGE AND IMPACT INFORMATION According to witnesses, the airplane banked steeply between two houses, located at 8230 South, to avoid hitting them before striking a dirt embankment. The dirt was from a basement that had been dug for another house under construction on High Summit Circle. The empennage and both wings remained next to the embankment. The propeller assembly, with one blade separated, was found 10 feet away. One of the attached blades bore 90 degree chordwise scratch marks on the cambered surface; the other attached blade was twisted midspan. The separated blade was twisted and bent aft. The leading edge at the tip was gouged. The cabin area was found approximately 110 feet beyond. The seatbelt and shoulder harness were fastened but both seatbelt anchors were torn from the floor. The firewall remained attached to the passenger cabin. A small grass fire surrounding the engine area was extinguished by local residents. The firewall, stainless steel shroud surrounding the turbocharger, muffler, and intake air line was extensively scorched and discolored. The engine was located in the backyard of a house on Mount Spencer Circle. It bore no evidence of fire impingement. The oil filter lay was beneath this house's dining room bay window [See attached Wreckage Distribution Chart]. MEDICAL AND PATHOLOGICAL INFORMATION On July 19, 1998, an autopsy (case #R199800888) and toxicological screen were performed on the pilot by Dr. Edward A. Leis of the Utah State Medical Examiner's Office. The pilot did not sustained thermal injuries. No drugs or alcohol were detected. FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, also performed a toxicological screen. According to CAMI's report (case #9800203001), no ethanol was detected. Tests for the presence of cyanide and carbon monoxide were not performed due to the lack of a suitable specimen. Less than toxic levels of Phenylpropanolamine and Ephedrine, commonly used as nasal decongestants, were detected in brain and muscle tissue. According to FAA's Deputy Regional Flight Surgeon Christopher S. Taylor, at the levels detected, the drugs would serve as "stimulants or performance enhancers." FIRE Witnesses said they saw flames and smoke coming from the engine area as the airplane descended. Examination of the wreckage, however, disclosed only scorching and discoloration on the firewall, stainless steel shroud surrounding the turbocharger, the muffler, and intake air line. In addition, the edge of the carpeting around the left rudder pedal had begun to melt. The separated engine bore no evidence of fire impingement. TESTS AND RESEARCH The wreckage was transported to Spanish Fork Flying Service, Spanish Fork, Utah, where, on July 20 and 21, the wreckage was examined in greater detail. Extensive scorching and discoloration were noted on the stainless steel shroud and firewall in the vicinity of the turbocharger. The muffler and intake air line were scorched and discolored. Synthetic fibers of the interior carpeting in and around the pilot's left rudder pedal were melted. Although the main fuel line bore evidence of high heat distress, it had not been breached except where it attached to the separated engine. The exhaust pipe was separated from the turbocharger, and the clamp that held it in place was found broken and had slipped down the pipe. Metal splatter, silver in color and similar to the insulation surrounding the turbocharger, was found on the turbocharger and mating lip, on the exhaust pipe and mating lip, and on the clamp. The turbocharger, exhaust pipe, clamp, and a sample of the silver insulation blanket were sent to NTSB's metallurgical laboratory for analysis. According to the metallurgist's factual report, the metal splatter observed on the turbocharger, exhaust pipe, and clamp contained small embedded fibers. When spectrographically analyzed with an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM), its elements were found to be "mostly aluminum and silicon with a significant amount of oxygen," similar in composition to the aluminum foil faced fiberglass insulation blanket submitted for examination. There was a brittle transverse fracture of the circumferential tensioning band. The tensioning band holds together two semi-circular clamping segments to make up the band clamp. The fracture was near one of two resistance spot welds. There was little evidence of material yielding except at the extreme edges of the band. The fracture initiated in the vicinity of the spot weld and propagated to both edges of the band as demonstrated by chevron patterns. At the spot weld location, the fracture was "curved and followed the elliptical contour of the spot weld's fusion zone." There was a heat tinting pattern on the tensioning band surface, darkest at the spot weld and lighter toward the edges. SEM examination of both halves of the fractured tensioning band disclosed "an area of oxidized ductile fracture" in the region corresponding to the fusion zone of the spot weld. The ductile area extended from the inner surface of the band outward through about half of the band's thickness. Immediately outside of the oxidized ductile, the fracture morphology became intergranular and showed no signs of ductility. It remained intergranular throughout the brittle region of the fracture. The ductile areas at each edge of the band had "ductile dimple topographies accompanied by significant amounts through the thickness yielding of the band material." Tests at room temperature on notched areas of the band material produced ductile fractures in both bending and tension with large amounts of plastic deformation and yielding. The tests also revealed preexisting cracks at both of the tested welds. Oxidized ductile features in the preexisting cracks were similar to those seen in the original fracture that separated the tension band. ADDITIONAL INFORMATION In addition to the Federal Aviation Administration, parties to the investigation were the Commander Aircraft Corporation and Textron Lycoming. The wreckage, with the exception of the turbocharger and associated exhaust plumbing, was released to the insurance company representative on July 22, 1998. The remaining parts were released to him on March 16, 1999.
A brittle fracture of the clamp that joins the exhaust pipe to the turbocharger. The pipe separated and hot exhaust gases escaped into the engine compartment. The engine lost power due to the high heat vaporizing fuel in the fuel line. Factors were inadequate quality control by the clamp manufacturer; the pilot's intentional maneuvering of the airplane to avoid houses and personnel, and the lack of suitable terrain on which to make a forced landing.
Source: NTSB Aviation Accident Database
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