SEMINOLE, OK, USA
N2934B
Beech D-35
The airplane was inbound to the airport when the engine lost power. Subsequently, the pilot lost control of the airplane while maneuvering to avoid a business, trees, a residence, people on the ground, and power lines. The airplane impacted the terrain in a nose low attitude and was destroyed by the impact sequence, ensuing explosion, and fire. A hole was found in the crankcase of the Continental E-225-8 engine over the #6 cylinder, and the #6 connecting rod was found separated from the rod journal. An engine teardown revealed that the engine exhibited a massive oil starvation event. The #6 connecting rod was disconnected from the crankshaft journal due to the heat of the oil starvation event, which resulted in the failure of the connecting rod bolts in ductile overload from the elevated temperature. The reason for the oil starvation could not be determined by examination of the engine or the airplane wreckage. The maintenance records were destroyed by the post-impact fire, and the maintenance history for the engine could not be determined.
HISTORY OF FLIGHT On August 23, 1999, at approximately 1854 central daylight time, a Beech D-35 single engine airplane, N2934B, impacted terrain during a forced landing following a loss of engine power near Seminole, Oklahoma. The airplane was owned and operated by the pilot under 14 Code of Federal Regulations (CFR) Part 91. The private pilot, sole occupant, received fatal injuries, and the airplane was destroyed. Visual meteorological conditions prevailed for the cross-country flight, and a flight plan was not filed for the business flight. The flight departed Tulsa, Oklahoma, at 1813. A review of the Tulsa Air Traffic Control (ATC) Tower data by the NTSB investigator-in-charge (IIC) revealed that the airplane departed the Tulsa International Airport on a VFR clearance for the direct flight to Seminole, Oklahoma. Upon departing Tulsa airspace, the flight was cleared to the requested cruise altitude of 3,500 feet msl. There were no additional en route transmissions to ATC. Witnesses and local authorities reported that the pilot announced at 1850, "Seminole traffic landing 34" over the airport's common traffic advisory frequency (CTAF). Witnesses then observed the airplane at an estimated altitude of 750 feet agl approximately 1 1/2 miles northeast of the airport with the engine "running real bad." Subsequently, the aircraft was observed flying toward the airport and maneuvering in the vicinity of the intersection of Highway 377 and County Road 119. Witnesses reported that the engine was sputtering and cutting out with smoke coming from the aircraft. Witnesses observed the airplane's extended landing gear. They further reported that the airplane descended to an altitude below the height of 60-foot power lines paralleling Highway 377 on the west. The airplane descended toward a convenience store, residences, and people on the ground before it suddenly climbed vertically and rolled inverted. Subsequently, the airplane crossed over the power lines and Highway 377, descended, and impacted the terrain in a nose low attitude. The airplane exploded upon impact and a fire erupted. PERSONNEL INFORMATION The 54-year-old pilot was a medical doctor for the Tri Cities Family Medical Clinic, at Wewoka, Oklahoma. In addition to his practice in Wewoka, he was performing medical duties at four prisons and the Tulsa, Oklahoma, jail. A review of the pilot's logbook and FAA records, by the NTSB IIC, revealed that the pilot began flight training in April 1997, was issued a third class medical certificate on June 18, 1997, and obtained his private pilot certificate on November 2, 1997. The pilot had accumulated a total of 608.4 hours. The pilot began flying N2934B on August 14, 1999, receiving his high performance endorsement in the airplane on August 17, 1999. At the time of the accident, the pilot had accumulated a total of 9.7 hours in the accident make and model airplane. The FAA records did not indicate any medical certificate had been issued for the pilot after June 18, 1997. AIRCRAFT INFORMATION The Beech D-35 airplane, serial number D-3575, was manufactured in 1953. The aircraft was registered to the pilot on June 16, 1999. Acquaintances of the pilot reported that the engine had accumulated approximately 400 hours since the last overhaul. Acquaintances further reported that the total airframe time was 4,500 hours, and the last annual inspection was performed in August 1999. Fire damage to the maintenance records found at the accident site precluded a determination of the history of the airframe or the Continental E-225-8 engine. A readable portion of one page indicated that the total aircraft time in May 1999, was 4,456.9 hours, and the propeller was overhauled in July 1999. METEOROLOGICAL INFORMATION Weather conditions at the accident site were reported by witnesses and local authorities as 98 degrees Fahrenheit, visibility 10 statute miles, high scattered clouds, and calm wind. AERODROME INFORMATION The Seminole Municipal Airport (H45), at an elevation of 1,021 feet, is a non-towered airport. The hard surface (asphalt) runway 16-34 is 5,007 feet long and 75 feet wide. The airport is serviced with a non-directional radio beacon (NDB) for navigation. The airport communications common traffic advisory/unicom frequency (CTAF) is 122.8 Megahertz (MHz). WRECKAGE AND IMPACT INFORMATION The accident site was in the southeast quadrant of the intersection of Highway 377 and Highway 99, approximately 3 miles north of Seminole, Oklahoma. The wreckage distribution path was on a measured magnetic heading of 280 degrees. The aircraft came to rest on a measured magnetic heading of 325 degrees adjacent to the east edge of Highway 377, approximately 1 mile north of the Seminole Municipal Airport. A crater, consistent with the dimensions of the propeller spinner and forward engine nacelle, was found at the site. Pieces of plexiglass were found near the west edge of the crater. A longitudinal ground scar, consistent with the length of the right wing, was found approximately 2 feet forward of where the right wing came to rest. The leading edge of the right wing was displaced aft. Examination of the engine revealed a hole over the #6 cylinder in the left crankcase half. The journal end of the #6 connecting rod could be observed through the hole. An additional hole was observed in the right crankcase half over the #5 cylinder attachment point. The engine had external thermal damage. The throttle and mixture controls were attached at the engine. The carburetor was destroyed. The engine was shipped to Mobile, Alabama, for further examination. See the test and research section of this report for additional information. Flight control continuity was confirmed. The landing gear actuator was found in the extended position, and the flaps were found in the retracted position. The cockpit and cabin areas were destroyed. The cockpit engine control cables were found in the full forward position. The single pivotal control yoke was positioned on the left side of the cockpit. One propeller blade separated from the propeller hub and was found at the initial impact crater, and the inboard leading edge of this blade exhibited scrape marks. The second propeller blade remained attached to the hub and the engine. This blade was bent aft. FIRE Thermal damage to the airplane wreckage was consistent with a fuel-fed fire erupting on impact. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by the Office of the Chief Medical Examiner, Oklahoma City, Oklahoma. The Medical Examiner determined that the cause of death for the pilot was multiple traumatic injuries consistent with blunt force trauma. No evidence of smoke inhalation was found. The aviation toxicological test was performed by the FAA Civil Aeromedical Institute's (CAMI) Forensic Toxicological and Accident Research Center. The CAMI toxicological findings were negative. TEST AND RESEARCH On October 14, 1999, the Continental E-225-8, engine serial number 31020-D-5-A, was examined under the surveillance of a NTSB investigator at Mobile, Alabama. The factory representative reported that the "engine exhibited a massive oil starvation event." The cause of the oil starvation could not be determined by examination of the engine. The #6 connecting rod was disconnected from the crankshaft journal "due to the heat of the oil starvation event, causing the [connecting] rod bolt fracture in ductile overload from the elevated temperature." ADDITIONAL INFORMATION The airplane was released to the owner's representative on December 17, 1999.
The loss of engine power caused by oil starvation, which resulted in the failure of the #6 cylinder connecting rod bolts. A factor was the pilot's performance of an evasive maneuver to avoid impacting buildings, trees, people on the ground, and power lines.
Source: NTSB Aviation Accident Database
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