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On July 8, 1997, at 0303 central daylight time, an Aero Commander 500-B airplane, N802TC, registered to a private owner and operated by M & M Aviation dba Pro Air Aviation as a Title 14 CFR Part 135 cargo flight, was substantially damaged during a forced landing, following a partial loss of power near Dallas, Texas. Dark night visual meteorological conditions prevailed, and a flight plan was not filed. The commercial pilot was seriously injured, and his pilot rated passenger sustained minor injuries. The flight originated from Dallas Love Field, Dallas, Texas, about 12 minutes before the accident.
According to a Love Field air traffic control tower controller, the pilot requested a runway 31R departure. After takeoff the pilot was instructed to climb to 2,000 feet and contact Fort Worth departure control. The pilot acknowledged the frequency change, and there were no further communications from the pilot. Radar contact was lost with the airplane 1.5 miles southwest of Addison Airport at an altitude of 800 feet msl.
The pilot-in-command (PIC) reported to the FAA inspector that after arriving at Dallas Love Field from Tulsa, Oklahoma, the aircraft was "topped off" with 90 gallons of fuel at Dalfort Aviation, and approximately 20 bundles of newspapers were loaded along with 2 to 3 boxes of checks. The cargo was loaded by him and the pilot rated passenger who had accompanied him on the flight from Tulsa. The cargo net was not used to secure the cargo.
The PIC further reported that on departure from Dallas Love Field, the pilot rated passenger was occupying the left seat. During takeoff the pilot rated passenger "was at the controls." During the climb out he realized there was some kind of problem because they were not gaining any altitude, so he "took the controls and applied 1/4 flaps to try and gain some altitude." The airspeed at that time was about 105 knots. He then retracted the flaps because his airspeed had deteriorated to about 90 knots. He stated that the "highest he ever got was about 800 feet MSL and was unable to maintain altitude." He also reported that "both engines appeared to be developing power, RPM 2,300 Manifold Pressure 26 inches with fuel flow, however he thought the right engine acted as if it were operating only on one mag." He reported that a magneto on the right engine was changed the day prior at Tulsa, Oklahoma.
The pilot rated passenger reported to the FAA inspector that he occupied the left seat on the flight that originated at Max Westheimer Airport, Norman, Oklahoma, stopping at Clinton, Oklahoma, Tulsa, Oklahoma, Dallas, Texas, with planned stops at Oklahoma City, Clinton, and terminating at Norman. He stated that the PIC was "his friend who was training him in the left seat."
The pilot rated passenger further reported that the takeoff roll at Dallas Love Field seemed to take longer than "normal" and at 50 feet the pilot retracted the landing gear and reduced power to climb power. At 300 feet the PIC retracted the flaps and "called out to air traffic 800 feet." He also reported that he did not notice any problems with the engines until after the airplane struck the first power line and then the right engine began making sounds like it was "cutting out."
During a telephone interview conducted by the investigator-in-charge, the PIC reported that the before takeoff run-up was "okay." He also reported he was at the controls during the takeoff, and the "power was good." The takeoff roll was longer than normal due to taking off downwind with winds from the southeast at 5 to 6 knots. Flaps and landing gear were retracted after attaining a positive rate of climb. During takeoff climb, about 300 to 400 feet agl, he "noticed the aircraft didn't feel right and the airspeed was slowly dropping off." Both manifold pressures and fuel pressures were "okay," and the engines were not "back firing or popping." At about 400 feet he nosed the aircraft over but the airspeed kept decreasing. He put in 1/4 flaps in an effort to gain altitude; however, the aircraft did not climb and he retracted the flaps. He headed the aircraft away from some tall buildings towards a dark area. While heading towards the dark area he only remembers the aircraft striking one set of power lines before impacting the houses.
The PIC also reported that he changed the right magneto on the right engine the day prior. The magneto would check out okay during ground checks, however, "it would intermittently cut out" in flight.
A witness reported in a telephone interview to the investigator-in-charge that about 0300 he heard an airplane flying low over his residence. One engine was "cutting out" and it was louder than the other engine, which "sounded okay." The witness lives 4 to 5 miles north northwest of Dallas Love Field and about 2 miles south of Addison Airport.
The commercial rated pilot-in-command's last biennial flight review was on January 16, 1997, and it was accomplished in an Aero Commander 500-B airplane. He had accumulated 1,800 flight hours in this make and model of aircraft, of which 60 hours were within the last 90 days and 15 hours within the last 30 days. His most recent medical was a second class dated April 21, 1997. Although he was the director of operations for M & M Aviation and rated to fly the airplane, according to the FAA, he was not named in the company's operations specifications as a pilot-in-command for Title 14 CFR Part 135 operations.
The passenger was a certificated commercial pilot, and rated in multiengine aircraft. Attempts to contact the passenger were unsuccessful, therefore, time flown in the make and model of the accident aircraft and multiengine aircraft could not be determine. FAA records indicate the pilot reported having accrued 1280 total flight hours on his last application for a first class medical examination, dated April 9, 1997. Although he was rated to fly the airplane, according to the FAA, he was not named in the company's operations specifications to be in the aircraft for Title 14 CFR Part 135 operations.
A review of the airframe and engine records did not reveal evidence of any anomalies or uncorrected maintenance defects. According to maintenance records, the aircraft's last annual inspection was completed on December 24, 1996, at a total aircraft time of 20,773.9 hours. At the time of the accident, the aircraft had accumulated a total time of approximately 21,065.8 hours.
The IO-540-E1A5 engine, S/N RL-223-48, was installed on the right hand side of the aircraft on December 24, 1996. An annual inspection was accomplished on the engine at the time of installation. The engine was last overhauled on October 23, 1992, with a total time 9,373.2 hours. At the time of the accident the engine had approximately 1,470.7 hours since overhaul with a total time of 10,843.9 hours.
The IO-540-E1A5 engine, S/N RL-186-48, was installed on the left hand side of aircraft on June 27, 1997. A 100 hour inspection was accomplished on the engine at the time of installation.
The weight of the aircraft at the time of the accident was estimated at 6,419 pounds. The maximum gross weight of the aircraft is 6,750 pounds. Performance data indicates the airplane's single engine rate-of-climb for the prevailing conditions of 81 degrees Fahrenheit and 377 feet pressure altitude was approximately 289 feet per minute with an indicated airspeed of 108 miles per hour. To attain this rate of climb the aircraft's flight manual states that you must "use maximum continuous power on operating engine (full throttle, 2,575 RPM) leaned to best power fuel flow, cowl flaps as required to control engine temperature within limits, landing gear up, flaps up. Inoperative engine feathered, cowl flaps closed. Climb at best rate of climb speed."
WRECKAGE AND IMPACT INFORMATION
An examination of the accident site by the FAA inspector revealed that the airplane struck two sets of power lines, struck the roof of one house, and then struck another house before coming to rest nose down up against a tree.
A TU Electric employee reported that part of the aircraft was located approximately 1 block south of the accident site. The piece was identified as the upper 12 to 14 inches of the vertical stabilizer. It was just north of large electrical transmission lines that run east to west, approximately 85 feet high. The upper electrical line was found damaged. The TU Electric employee further reported that an electrical line one half mile southwest of the accident site was down.
Examination of the aircraft wreckage revealed that the right wing was separated just outboard of the right engine. The left wing was structurally damaged and its fuel tank was ruptured. Both engines were separated from their mounts. Oil soaked rags were found in the right engine nacelle. The main landing gear were down and the nose landing gear was within the aircraft's crushed nose. The right main landing gear up lock was fractured. Two of the three right propeller blades had gouges in the leading edge. Chordwise scratching was noted on two of the three left propeller blades. One of the left propeller blades was curled forward, and one blade exibited "S" bending.
A fuel sample was taken from the right fuel cell by the FAA inspector, and it appeared to be "normal." A fuel sample was taken by another FAA inspector from the fuel truck which fueled the aircraft at Dalfort Aviation, Dallas Love Field, and it was "normal."
Examination of the aircraft's cockpit at Air Salvage Of Dallas, Lancaster, Texas, by the investigator-in-charge revealed that the landing gear control lever was half way between the up and down position. The flap control lever was in the full down position, and all throttle, mixture, and propeller controls were full forward. Examination of the flap actuator by another NTSB investigator revealed it to be fully extended and the exposed actuating rod was measured at 3 inches. According to the aircraft manufacturer, this would equate to the flaps being fully extended.
TESTS AND RESEARCH
A visual examination of both engines was accomplished at Air Salvage of Dallas on July 16, 1997.
Examination of the left engine did not reveal any pre-impact anomalies.
A magneto timing check of the right engine revealed that the magneto timing for the left magneto was set at 7.1 degrees and the right magneto was set at 25 degrees. The data plate showed the timing should be set at 20 degrees. The right magneto had screws missing from the ignition lead cover plate and the cover plate was separated from the magneto.
The right magneto had been changed on July 7, 1997, at Tulsa, Oklahoma, the day prior to the accident. The magneto which had been replaced was found in the aircraft wreckage. This magneto was to exchanged for the magneto which was purchased from EMI Aircraft Accessories, Inc., at Tulsa, Oklahoma, by Pro Air Aviation on July 7, 1997. On August 14, 1997, the magneto was returned to EMI Aircraft Accessories, Inc., and bench tested. The "mag ran good, come in speed [was] 175 rpm & good drop at 1,000 rpm."
A compression check was done to all six cylinders of the right engine. The results were: #1 cylinder 0/80, #2 cylinder 75/80, #3 cylinder 55/80, #4 cylinder 0/80, #5 cylinder 18/80, #6 cylinder 30/80.
The IO-540-E1A5 right engine, S/N RL-223-48, was shipped to Textron Lycoming in Williamsport, Pennsylvania, for further examination. The engine was examined on November 12, 1997, and was witnessed by a FAA inspector. The inspector reported that there was no thumb compression on cylinders #1, #3, and #4. Cracks were found in cylinders #1 and #4 in the vicinity of their intake ports, and they were 2 inches in length with black deposits. An unusual appearance was noticed in the intake chambers, so at the direction of the investigator-in-charge, the #4 cylinder was sent to Textron Lycoming's materials laboratory for further examination.
The examination of the #4 cylinder head revealed a ruptured hole with cracks extending on both sides on the side wall of the intake port. The ruptured hole area was bulged out from the intake port. The intake port valve guide boss area displayed a smeared smooth surface which was viewed from the intake port flange and metal rolled-over on the opposite side. A "severe" metal rolled-over ridge was also observed at the end of the intake port flange area. These results indicated the area appeared to have been "severely modified in the field."
Examination of the intake pipe revealed an area was bulged out about two fifths of the circumferential area just behind the flange. A more pronounced rolled-over ridge was present at the flange end of the intake pipe with almost the same width as the bulged area. Inside of the pipe at the bulged area there was surface damage with some nicks "indicating the area had been bulged out by using a mechanical method, not by excessive heat and pressure."
An examination of the ruptured area of the intake port revealed that "10084-6" was inscribed above the ruptured hole and "90226-02" was inscribed underneath of the hole. Additional numbers "90226-02 7-19-91" and "8.91 CP 91157.05" were inscribed at the bottom of the cylinder barrel. "These designations appear to have been made by a rework facility in the field." See the enclosed Textron Lycoming Materials Lab report.