FTW98FA216

According to witnesses, the twin-engine airplane took off and was climbing when a reduction in engine power was heard. The airplane was observed leveling off, and a left turn back to the airport was initiated. The airplane was observed in level flight for a few seconds and then it rolled to the left and impacted on a highway in a nose low attitude. A post impact fire destroyed the airplane. The logbooks for the airplane and engines were not made available during the investigation. The minimum controllable airspeed (Vmc) was listed at 76 mph in a brochure provided by the previous owner of the airplane. Examination of the left engine revealed that the #2 cylinder's exhaust valve had failed in fatigue. Closer examination of the exhaust valve and its guide revealed that a portion of the valve guide was missing. Carbon deposits on the valve stem provided evidence that the engine had been operated for some period of time in this condition. Examination of the left turbocharger revealed that it was not rotating at the time of the accident; however, its turbine wheel blades displayed foreign object damage, more than likely resulting from portions of the separated exhaust valve head passing through the turbocharger. Examination of the propellers revealed that neither propeller was in the feather position at the time of the impact, and the left propeller was being operated at no or low power at impact. The left propeller control lever was found in the aft (feather) position.

History of flight

On May 16, 1998, approximately 0750 central daylight time, a Beagle B-206 twin-engine airplane, N1885S, was destroyed when it impacted terrain in an uncotrolled descent following a loss of left engine power shortly after takeoff from the Wilbarger County Municipal Airport, Vernon, Texas. The airline transport pilot and her two passengers sustained fatal injuries. The airplane was registered to and operated by Bradson Properties of Vernon, Texas. Visual meteorological conditions prevailed for the Title 14 Code of Federal Regulations Part 91 personal flight for which a visual flight rules flight plan was filed. The flight was destined for Austin, Texas.

According to witnesses, the airplane departed from runway 02, and the landing gear was retracted during the initial "normal climb." Soon after takeoff, a reduction in engine power was heard. The airplane was observed leveling off, and turning left back toward the airport. The airplane was observed in level flight for a few seconds and then it "rapidly" rolled to the left and impacted State Highway 283 in a nose low attitude.

Personnel information

The pilot, who was occupying the left front seat of the airplane, obtained her private pilot certificate with an airplane single-engine land rating in 1985. She obtained her commercial certificate with an airplane single-engine land rating in December 1985. In 1986, the pilot obtained a commercial multi-engine rating along with instrument single and multi-engine airplane ratings. In 1987, the pilot obtained a certificated flight instructor rating in single-engine airplanes. In 1990, the pilot received a commercial rating in helicopters, and later that same year obtained a flight instructor rating in helicopters. In November 1991, the pilot obtained an airline transport pilot certificate in multi-engine airplanes. In 1992, the pilot received a flight instructor rating in multi-engine airplanes. The pilot was issued a second-class medical certificate with a limitation to wear corrective lenses on September 4, 1997. Her last biennial flight review was completed on January 17, 1998, in the accident airplane. The pilot had accumulated a total of 3,506 flight hours, of which 1,707 hours were in multi-engine airplanes, and 41 hours were in the same make and model as the accident airplane. Within the 30 days prior to the accident, the pilot had flown 22 hours, of which 16 hours were in the same make and model as the accident airplane.

Aircraft information

The 1969-model six-place un-pressurized twin-engine airplane was equipped with two Teledyne Continental GTSIO-520-C 340-horsepower engines. Each engine had an Allied Signal Model T11 turbocharger (part number 404360-9004) installed. The 3-blade McCauley propellers had full feathering capabilities and un-feathering accumulators. The airplane was registered to Bradson Properties on April 7, 1998. The logbooks for the airplane and engines were not made available to the NTSB investigator-in-charge (IIC). Work orders, invoices, and other related paperwork, dated back to 1989, indicated the following information concerning the engines:

On April 4, 1989, the left engine (serial number 150739-7-C) was "repaired for damage to [the] crankcase from starter adapter," and "each cylinder cracked in exhaust port." An inventory list attached to the April 4, 1989, work order indicated that 6 pistons, 6 ring sets, 5 chromed cylinders, and 1 valve guide (part number C641951P005) had been purchased.

An invoice, dated March 3, 1994, indicated that 5 piston pins, 5 pistons, and 1 gasket set for top overhaul had been purchased. The engine that these parts were intended for was not specified on the invoice.

An invoice, dated June 28, 1994, indicated that a technician "troubleshot oil blow by problem" and "all cylinders" had been removed and replaced with newly overhauled cylinders. That same invoice indicated that a turbocharger was removed, overhauled, and reinstalled. It was not clear whether the cylinder and turbocharger replacements were conducted on one or both engines.

A work order invoice, dated January 4, 1995 (for work conducted between November 15, 1994, and November 30, 1994), indicated that the left engine had an "oil leak." According to the invoice, the engine was ground run and the #2 and #6 cylinders were found cracked. The #2 and #6 cylinders and piston assemblies were removed and replaced with "2 overhauled cylinder assemblies with piston and ring assemblies." That invoice reported the aircraft total time as 2,711.9 hours.

An invoice, dated January 12, 1995, indicated that 1 cylinder ring kit, 1 cylinder gasket kit, 1 valve guide, and a serviceable piston were purchased. The invoice also indicated that a technician "replaced valve guide and reground all valves and seats." The engine, on which this work was conducted, was not specified. The aircraft and engine total times were not recorded on this invoice.

A letter, dated March 15, 1995, indicated that work had been performed on one of the engines' turbochargers; however, the serial number listed on the letter did not match either of the two serial numbers found at the accident site.

A note, dated January 24, 1998, reported that an annual and 100-hour inspection had been conducted on the aircraft at a total time of 2,905 hours. According to this note, the left engine had accumulated 581 hours since its last overhaul, and the right engine had accumulated 1,054 hours since its last overhaul.

An invoice, dated May 1, 1998 (for work conducted between February 17, 1998, and April 30, 1998), reported a maintenance discrepancy noting a left engine oil leak. The ensuing engine run-up revealed that "bolt...on starter adapter leaks. Dampner shaft leaks, oil cooler leaks bad, vacuum pump leaks. Found loose fitting on vacuum. Tightened and sealed fitting and 2 plugs. Replaced push rod housing seals on #2, #4, #6 cylinder. Replaced rocker catch gaskets on #2, #4, #6 cylinder. Replaced oil pan gasket. Replaced starter o-ring...Removed oil cooler and replaced gasket." An additional maintenance item reported that left engine's propeller governor cable was evaluated and determined to be "O.K." It was not noted why the cable needed evaluating. The endorsement for the aforementioned work on the left engine indicated that the airplane had accumulated a total of 2,942 flight hours, and the left engine had accumulated a total of 714.9 hours since its last overhaul.

An undated document, which appeared to be a sales advertisement for the aircraft, listed the aircraft total time as 2,875 hours, and a right engine total time since its last overhaul as 1,024 hours. The aircraft total time from the advertisement was subtracted from the aircraft total time from the May 1, 1998, invoice to obtain a total of 67 hours. That time was then added to the right engine time since overhaul to obtain an estimated total time since overhaul of 1,091 hours for the right engine at the time of the May 1, 1998, invoice.

The May 1, 1998, invoice was the latest piece of maintenance information provided to the NTSB. The total time of the aircraft and engines at the time of the accident could not be determined.

The airplane was last topped off with fuel during the morning of the accident, when 85 gallons of 100LL aviation fuel were added at the Wilbarger Airport. The total fuel capacity of the airplane was 235 gallons.

The minimum controllable airspeed (Vmc) was listed at 76 mph in a brochure provided by the previous owner of the airplane.

Meteorological information

Wichita Falls, Texas (located 42 miles southeast of the accident site) was the nearest weather reporting station to the accident site. At 0756, Wichita Falls was reporting the wind from 150 degrees at 4 knots, visibility 10 statute miles, scattered clouds at 25,000 feet, temperature 17 degrees Celsius,