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On September 30, 1999, at 2240 central daylight time, a Cessna 150F single-engine airplane, N8092S, was substantially damaged when it impacted terrain while landing at the Robert S. Kerr Airport (RKR) near Poteau, Oklahoma. The flight instructor received serious injuries, and the student pilot, who was the owner of the airplane, was fatally injured. Dark night visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 instructional flight. The cross-country flight originated from RKR at 1955, completed planned landings at McAlester, Oklahoma, and Henryetta, Oklahoma, and was returning to Poteau at the time of the accident.
The three leg cross-country flight was planned from RKR to McAlester, Oklahoma (MLC), to Henryetta, Oklahoma (F10), with a return leg to RKR. During a telephone interview conducted by the NTSB investigator-in-charge (IIC), the instructor pilot stated that the student pilot flew his airplane from Ozark, Arkansas (the student pilot's home base, located 48 nautical miles northeast of RKR), and arrived at RKR "late and unprepared" at 1900. The instructor helped the student prepare for the cross-country; however, because they were running late, the instructor performed the fuel calculations (based on a 4-hour endurance minus the fuel used during the flight to RKR) in his head. The instructor determined that they had sufficient fuel remaining for the 2.5-hour cross-country and a 45-50 minute reserve; therefore, they did not refuel the airplane prior to the night cross-country flight.
The instructor reported that while "en-route, just outside of MLC, the generator light illuminated." The instructor stated that the student believed that the light was a false indication so they elected to perform a touch-and-go at MLC and continue with the flight. The instructor added that they could not activate the pilot controlled lighting at F10 until they were within one mile of the airport, but they "did not think much of it at the time because the airplane normally had to be close to that airport to activate the lights." They performed a touch and go landing at F10 and elected to return to RKR, even though the generator light was still illuminated.
During the last leg of the flight, the flight instructor stated that the fuel gauges were indicating empty in one fuel tank and 1/4 full in the other fuel tank. The student then informed the instructor that his aircraft's endurance was approximately 3.5 hours. According to the instructor, the airplane lost electrical power before the flight reached RKR. Due to the fuel situation, the instructor elected to continue to RKR instead of diverting to an airport with automatic runway lighting.
Upon arriving at RKR, the flight instructor was unable to activate the pilot controlled runway lighting system using the aircraft radio. The flight instructor set up for the first landing approach to runway 18 with no runway or airplane lighting. A Precision Approach Path Indicator (PAPI), consisting of 2 identical light units placed on the left side of runway 18, was illuminated at the time of the approach. When the airplane descended, the flight instructor was "blinded" by the PAPI lights and could not ascertain his distance from them, so he elected to abort the approach. He elected to attempt another approach to runway 36, with the knowledge that there was a grass strip to the east of the runway. According to the instructor, the student pilot turned on a flashlight to look at the instruments about the same time the airplane touched down in a rough area to the east of runway 36. The airplane bounced 3 or 4 times, and impacted a ditch in a nose down attitude.
The instructor pilot was issued a flight instructor certificate on July 22, 1998, and a second class medical certificate on February 17, 1999, with a limitation: must wear corrective lenses. According to the enclosed Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the instructor pilot had accumulated 1,178 hours of total flight time, of which 744 hours were in the same make and model as the accident airplane. The instructor had accumulated 637 hours of instruction given, of which 535 hours were in the same make and model as the accident airplane. He reported that he had accumulated a total of 62 hours of night flying experience. His last biennial flight review was accomplished on March 22, 1999.
The student pilot was issued a student pilot certificate on December 28, 1998, along with a third class medical certificate with the limitation: must wear lenses for distant-possess glasses for near vision. According to the student pilot's logbook, he had accumulated 125 hours of total flight time, of which all but 0.3 hours were in the accident airplane. Prior to the accident flight, the student logged 1.7 hours of dual night flying experience.
The Robert S. Kerr Airport has one runway, 18-36. Runway 18-36 is 4,006 feet long and 75 feet wide. The medium intensity runway lights (MIRL) are pilot activated over the common traffic advisory frequency. On the evening of October 1, 1999, an airplane manufacturer representative witnessed an aircraft activate the MIRL. The airport has a beacon, which operates between dusk and dawn, located to the east of the runway near the south end of the airport. The PAPI, located on the approach end of runway 18, was operating at the time of the accident.
At 2300, the weather observation facility at Fort Smith, Arkansas (located 22 miles northeast of the accident site), reported the wind as calm, visibility 10 statute miles, sky clear, temperature 48 degrees Fahrenheit, dewpoint 43 degrees Fahrenheit, and an altimeter setting of 30.09 inches of mercury.
On September 30, 1999, the U.S. Naval Observatory reported that the time of sunset at Poteau, Oklahoma, was 1904. Moonrise was at 2320, on September 30, 1999, and moonset was at 1351, the following day. The phase of moon was waning gibbous with 66% of the moon's visible disk illuminated.
The accident airplane was purchased by the student pilot in November 1998, and was registered to the student pilot on March 20, 1999. Review of the maintenance records revealed that the last annual inspection was completed on November 17, 1998, at a tachometer time of 3155.9 hours. On December 4, 1998, the engine maintenance records indicated that an overhauled generator was installed. On that same day, a new voltage regulator was installed on the engine firewall. Work orders, located with the maintenance records, revealed that the same facility that completed the annual inspection replaced the rotating beacon bulb and the landing and taxi lights on July 8, 1999. On July 15, 1999, the facility replaced the voltage regulator and the generator "fuses." The amperage of the generator fuses installed was not indicated on the work order.
According to acquaintances of the student pilot, the generator light illuminated during a flight approximately one month prior to the accident. They also reported that the flap fuses had blown on two separate occasions, and the landing and taxi lights had failed. The flight instructor stated that during a local night flight on September 23, 1999, the generator warning light illuminated about 40 minutes into the lesson. The instructor reported that he asked the student to get the airplane fixed. The student informed the instructor (during the accident flight) that when he flew the airplane following the September 23rd flight, the generator warning light did not illuminate and he thought it was an "indication problem."
The 1965 model airplane was not equipped with shoulder harnesses as they were not required during the airplane's certification.
The FAA inspector, who responded to the accident site, stated that the airplane initially touched down about 360 feet east of the runway centerline in a ditch. The airplane continued along the ditch for another 363 feet before coming to rest. The airplane's forward fuselage was structurally damaged, and the nose and main landing gear were collapsed.
According to the FAA inspector, he and an airplane manufacturer representative examined the electrical fuses at the accident site. The FAA inspector stated that at least 4 of the 7 fuses were not the proper amperage, and one of them was "blown."
The airplane was recovered to Air Salvage of Dallas, Lancaster, Texas, for further examination.
TESTS AND RESEARCH
On November 3, 1999, the NTSB IIC examined the accident airplane with representatives from the airplane and engine manufacturers. The aircraft's electrical system was examined. The Cessna 150F was certified for either a 20-amp or 35-amp electrical system. The accident aircraft had a 35-amp electrical system and required a 35-amp fuse in the generator fuse holder. A 30-amp fuse was found in the generator fuse holder in a "blown" condition. Three other fuses were found with higher than required amperage; however, they were not blown.
The 12-volt/35-amp Aero Electric Generator (part number: 1101898, serial number: A-136868) and the 14-volt/35-amp Electro Delta Voltage Regulator were removed and tested. The generator displayed an isolated area of arcing signatures on its commutators and its brushes displayed even wear. The generator was bench tested with the voltage regulator and no anomalies were noted. Checks for opens and shorts in the generator revealed none.
On November 22, 1999, the generator was tested and examined at the manufacturer's facility under the supervision of an FAA inspector. No defects were noted during the functional and visual examinations. The discoloration noted on the generator's commutator segments was "probably due to overheating [and] did not have any effect on the operation of the unit."
The wreckage was released to the owner's representative.