Burlington-Alamance

The pilot departed in night instrument flight rules (IFR) conditions on a medical specimen transport flight. During the climb, an air traffic controller told the pilot that the transponder code he had selected (2501) was incorrect and instructed him to reset the transponder to a different code (2531). Shortly thereafter, the airplane reached a maximum altitude of about 3,300 ft and then entered a descending right turn. The airplane’s enhanced ground proximity warning system recorded a descent rate of 11,245 ft per minute, which triggered two “sink rate, pull up” warnings. The airplane subsequently climbed from an altitude of about 1,400 ft to about 2,000 ft before it entered another turning descent and impacted the ground about 5 miles northeast of the departure airport. The airplane was fragmented and strewn along a debris path that measured about 800-ft long and 300-ft wide. Postaccident examination of the airplane did not reveal any preimpact mechanical malfunctions that would have precluded the pilot from controlling the airplane. The engine did not display any evidence of preimpact anomalies that would have precluded normal operation. An open resistor was found in the flight computer that controlled the autopilot. It could not be determined if the open resistor condition existed during the flight or occurred during the impact. If the resistor was in an open condition at the time of autopilot engagement, the autopilot would appear to engage with a mode annunciation indicating engagement, but the pitch and roll servos would not engage. The before taxiing checklist included checks of the autopilot system to verify autopilot function before takeoff. It could not be determined if the pilot performed the autopilot check before the accident flight or if the autopilot was engaged at the time of the accident. The circumstances of the accident are consistent with the known effects of spatial disorientation. Dark night IFR conditions prevailed, and the track of the airplane suggests a loss of attitude awareness. Although the pilot was experienced in night instrument conditions, it is possible that an attempt to reset the transponder served as an operational distraction that contributed to a breakdown in his instrument scan. Similarly, if the autopilot’s resistor was in an open condition and the autopilot had been engaged, the pilot’s failure to detect an autopilot malfunction in a timely manner could have contributed to spatial disorientation and the resultant loss of control.

The pilot transmitted on unicom that he was on final for runway 24. Following a double fuel starvation power loss the airplane impacted nose low with trees and terrain about 2.6 miles from runway 24. Last fueling occurred on the previous day at Albermarle, NC, the pilot's primary source of fuel, 50 miles from Burlington. The flight proceeded to Burlington, Teterboro, and was returning to Burlington. Total estimated flight time was 4 hours 32 minutes. Fuel burn was calculated to be 361 gallons. Usable fuel was 384 gallons and 24 gallons were recovered from the right center tank. If the fuel transfer pump does not operate 28 gallons will be unusable. That pump was found in the off position. No fuel spillage occurred at the scene. On 2/8/90 the pilot purchased 361 gallons of fuel for N110LT. Lower fuel prices at the favored location were the pilot's reason for fueling there. Examination of engines, propellers, fuel pumps, and other relative components did not reveal any significant discrepancy. Both occupants were killed.

Before departing Youngstown, OH, the pilot filed two IFR flight plans, one for a flight to Plattsburgh, NY, the other for a return flight from Plattsburgh back to Youngstown. After a 2 hour and 10 minutes flight to Plattsburgh, 70 gallons of fuel was added, but the person who serviced the aircraft indicated the tanks were not full after servicing. The plane then made a 10 minutes flight to Burlington, VT, but no fuel was added at Burlington. The pilot then took off on a return flight to Youngstown. During the descent phase to Youngstown, the pilot requested vectors to the closest airport. He was provide vectors to the Chess Lamberton Airport and advised it was 6 miles away. A short time later, the pilot said the aircraft had lost power. Subsequently, it crashed in rolling, wooded terrain. During an exam, no fuel was found in the aircraft. No other evidence of a malfunction or failure was found. With the passenger and cargo load, a maximum of about 104 gallons of fuel could have been used without exceeding the certificated gross weight of the aircraft. At 45 to 55% power, the aircraft burned 17 to 22 gallons per hour. Wind gusts 30 knots. All six occupants were killed.