San Angelo-Mathis Field

While on final approach to San Angelo-Mathis Field, the single engine airplane entered a rapid descent with a rate of 5,058 feet per minute then crashed in an open field located about 12 km south of the airport. The airplane was totally destroyed and both occupants were killed.

The pilot reported that, during the approach and while the airplane was about 500 ft above ground level and 81 knots, he "felt the descent rate increase significantly." The pilot increased engine power, but "the high rate of descent continued," and he then increased the engine power further. A slow left roll developed, and he applied full right aileron and full right rudder to arrest the left roll. He also reduced the engine power, and the left roll stopped. The pilot regained control of the airplane, but the airplane's heading was 45° left of the runway heading, and the airplane impacted trees and then terrain. The airplane caught fire, and the pilot and passenger exited through the emergency exit. The airplane sustained substantial damage to the windscreens and fuselage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.

The airplane impacted a dirt field and a power line following a loss of control during a simulated engine failure while on a Part 135 proficiency check flight. Both pilots were seriously injured and could not recall any details of the flight after the simulated engine failure. Witnesses observed the airplane flying on a westerly heading at an altitude of 100 to 200 feet, and descending. They heard the sound of an engine “surging” and observed the airplane’s wings bank left and right. The airplane continued to descend and impacted the ground and power lines before becoming inverted. A pilot-rated witness reported that he observed about ¼ inch of clear and rime ice on the airplane’s protected surfaces (deice boots) and about ½ inch of ice on the airplane’s unprotected surfaces. An NTSB performance study of the accident flight based on radar data indicated that the airplane entered a descent rate of 1,300 feet per minute (fpm) about 1,100 feet above the ground. This rate of descent was associated with a decrease in airspeed from 130 knots to 92 knots over a span of 30 seconds. The airplane’s rate of descent leveled off at the 1,300 fpm rate for 45 seconds before increasing to a 2,000 fpm descent rate. The true airspeed fluctuated between a low of 88 knots to 102 knots during the last 45 seconds of flight. According to the aircraft manufacturer, the clean, wing flaps up stall speed was 78 knots. However, after a light rime encounter, the Pilot’s Operating Handbook (POH) instructed pilots to maintain additional airspeed (10 to 20 KIAS) on approach “to compensate for the increased pre-stall buffet associated with ice on the unprotected areas and the increased weight.” With flaps up, a minimum approach speed of 105 KIAS was recommended. The POH also stated that a significantly higher airspeed should be maintained if ½ inch of clear ice had accumulated on the wings.

During takeoff, the twin-engine airplane was observed to roll left, pitch nose down, and impact terrain shortly after the pilot reported to ATC that he had a problem. Witnesses reported that the left engine was producing black smoke during the takeoff roll. One witness stated that the airplane had slowed to approximately 60-70 mph prior to rolling to the left. A mechanic, who worked on the airplane prior to the accident, stated that the pilot reported being unable to maintain manifold pressure (MP) with the left engine. The mechanic found that the left engine's rubber interconnect boot, which routes induction air between the turbocharger controller elbow and the fuel servo, was 'gaping open.' The mechanic reseated the boot and tightened the clamp. The pilot flew the airplane and reported no problems. During a second flight, the pilot reported that the left engine was again unable to maintain MP. Prior to the accident flight, the pilot informed the mechanic that the 'hose had slid off again' and that it had been reinstalled and he 'felt sure it was o.k.' A witness stated that he saw the pilot working on the left engine the morning of the accident. At the accident site, the left engine's interconnect boot was found disconnected. The clamp securing the boot was not located. No other preimpact anomalies were found with the engines, propellers, turbochargers, or fuel servos.

Witnesses observed the airplane contact the water while buzzing a lake, 'emerge from a cloud of water,' and enter a climb trailing white vapor. As the airplane approached the lake shore, the right propeller 'quit turning,' then the airplane entered a steep right bank and impacted the ground. The right propeller lever was found in the feather position. Propeller teardowns revealed signatures indicating the right propeller was feathered and the left propeller was operating in the low pitch range at impact. Disassembly of the engines revealed no evidence of any pre-impact mechanical anomalies, and, in the opinion of the manufacturer, 'both engines appeared capable of producing power prior to impact.' Toxicological tests showed 178.000 mg/dl (0.178%) ethanol in vitreous fluid, 90.000 mg/dl (0.09%) ethanol in blood, 114.000 mg/dl (0.114%) ethanol in brain fluid, 3.000 mg/dl acetaldehyde in brain fluid, 22.000 mg/dl acetaldehyde in blood, and 4.000 mg/dl 2-propanol in brain fluid. The levels of ethanol found indicate ingestion of alcohol, and the levels of acetaldehyde and 2-propanol (metabolites of ethanol) detected support ingestion of alcohol.

Aircraft was destroyed during an attempted off airport emergency landing following a dual engine failure while leveling off at cruise flight. Pilot stated that left engine, then right engine surged and quit as he was leveling off at 9,000 feet msl. At the time of the engine failures the fuel totalizer was reading 60 gallons, but the aircraft fuel gauges were reading empty. Pilot broke out of overcast at 3,500 msl (about 1,200 feet agl) and was unable to find a suitable clear area to land before committing to an emergency landing in trees. Gear was down, flaps were up and neither engine was feathered at impact. Pilot stated that he knew he was out of gas when both engines quit and that he did not attempt an air start. Both occupants were seriously injured.

The pilot had recently purchased the aircraft and received 25 hours dual instruction to comply with his insurance requirements. Shortly thereafter he went out solo to practice steep turns. He climbed to 12,500 feet and leveled off. He then rolled into a 60° left bank at 200 knots airspeed by applying left aileron and back pressure. He then applied moderate left rudder. At this time the nose came up, the right wing came over the top, the nose tucked down and the aircraft entered a steep nose down spin. In his attempt to stop the spin the pilot shut down both engines. He got the spin stopped after 15 to 20 turns. He started pulling the nose up and the stall buffet was felt. Alt was 500 feet agl at this time and he was unable to restart the engines. He then made a gear up landing in a pasture which resulted in destruction of the aircraft. The pilot was uninjured.

On approach to Henderson-Sky Harbor Airport, the pilot encountered technical problems with the fuel supply system. On final, the twin engine airplane stalled and crashed in a rocky area located one mile short of runway. The aircraft burst into flames and the pilot, sole on board, was killed.

Upon touchdown at San Angelo-Mathis Field Airport, the twin engine airplane swerved then nosed over and came to rest in flames. All four occupants escaped with minor injuries while the aircraft was destroyed.

While in cruising altitude, the twin engine airplane entered an uncontrolled and crashed in flames in an open field. The pilot, sole on board, was killed.