Rattan, OK, USA
N1551C
BEECH C90A
The pilot stated that the engine start and airplane power-up were normal for the air medical flight with two medical crewmembers. The engine ice vanes were lowered (as required for ground operations) and then were subsequently raised before takeoff. Takeoff and climbout were routine, and the pilot leveled off the airplane at the assigned cruise altitude. The air traffic controller informed the pilot of heavy showers near the destination airport, and the pilot "put the ice vanes down." The pilot indicated that, shortly afterward, the airplane experienced two "quick" electrical power fluctuations in which "everything went away and then came back," and "[s]econds later the entire [electrical] system failed." Due to the associated loss of navigation capability while operating in instrument meteorological conditions (IMC), the pilot set a general course for better weather conditions based on information from his preflight weather briefing. While the pilot attempted to find a suitable hole in the clouds to descend through under visual conditions, the left engine lost power. The pilot ultimately located a field through the cloud cover and executed a single-engine off-airport landing, which resulted in substantial damage to the right engine mount and firewall. A postaccident examination of the airplane and systems did not reveal any anomalies consistent with an in-flight electrical system malfunction. The three-position ignition and engine start/starter-only switches were in the ON position, and the engine anti-ice switches were in the ON position. When the airplane battery was initially checked during the examination, the voltmeter indicated 10.7 volts (normal voltage is 12 volts); the battery was charged and appeared to function normally thereafter. The loss of electrical power was likely initiated by the pilot inadvertently selecting the engine start switches instead of the engine anti-ice (ice vane) switches. This resulted in the starter/generators changing to starter operation and taking the generator function offline. Airplane electrical power was then being supplied solely by the battery, which caused it to deplete and led to a subsequent loss of electrical power to the airplane. A postaccident examination revealed that neither wing fuel tank contained any visible fuel. The left nacelle fuel tank did not contain any visible fuel, and the right nacelle fuel tank appeared to contain about 1 quart of fuel. The lack of fuel onboard at the time of the accident is consistent with a loss of engine power due to fuel exhaustion. This was a result of the extended flight time as the pilot attempted to exit instrument conditions after the loss of electrical power to locate a suitable airport. Further, the operator reported that 253 gallons (1,720 lbs) of fuel were on board at takeoff, and the accident flight duration was 3.65 hours. At maximum range power, the expected fuel consumption was about 406 lbs/hour, resulting in an endurance of about 4.2 hours. Thus, the pilot did not have the adequate fuel reserves required for flying in IMC. Both the pilot and medical crewmembers described a lack of communication and coordination among crewmembers as the emergency transpired. This resulted in multiple course adjustments that hindered the pilot's ability to locate visual meteorological conditions before the left engine fuel supply was exhausted.
On February 14, 2017, about 1145 central standard time, a Beech C90A twin-engine airplane, N1551C, was substantially damaged during a precautionary landing following a loss of power on one engine near Rattan, Oklahoma. The pilot and two medical crew members on board were not injured. The airplane was registered to and operated by EagleMed LLC under the provisions of Title 14 Code of Federal Regulations Part 135 air medical flight. The pilot stated that the engine start and airplane power-up were normal. The engine ice vanes were lowered, and the de-icing system was activated as required for ground operations. The ice vanes were subsequently raised before takeoff. Takeoff and climb out were routine, and he subsequently leveled off the airplane at 7,000 ft. mean sea level (msl). The air traffic controller informed him of "heavy rain showers" near the destination airport and he "put the ice vanes down." Shortly afterward, the airplane experienced two "quick" electrical power fluctuation; "everything went away and then came back." "Seconds later the entire [electrical] system failed." Due to the associated loss of navigation capability while operating in instrument meteorological conditions, the pilot set a general course for better weather conditions based upon the preflight weather briefing. During the attempt to find a suitable hole in the clouds to descend through under visual conditions, the left engine lost power. The pilot ultimately located a field through the cloud cover and executed a single engine precautionary landing. The nose landing gear collapsed, and the airplane sustained substantial damage to the right engine mount and firewall. A postaccident examination was conducted by Federal Aviation Administration inspectors and operator personnel. The left propeller blades were bent aft and did not exhibit any curling of the blades. The right propeller blades were curled in the direction of rotation. The left- and right-wing fuel tanks did not contain any visible fuel. The left nacelle fuel tank did not contain any visible fuel. The right nacelle fuel tank appeared to contain about one quart of fuel. The three-position Ignition and Engine Start/Starter Only switches on the cockpit instrument panel were in the ON position. The Engine Anti-Ice switches were in the ON position. The cabin medical bed electrical switches corresponding to the inverter and accessories were in the ON position; the remaining medical bed switches were OFF. A postrecovery examination was conducted by the NTSB investigator-in-charge and operator personnel. No anomalies consistent with an in-flight electrical system malfunction were observed. When the airplane battery was initially checked during the exam the voltmeter indicated 10.7 volts; the battery was charged and appeared to function normally thereafter. The operator reported that 253 gallons (1,720 lbs.) of fuel were onboard at takeoff and the airplane gross weight was 7,838 lbs. The accident flight duration was 3.65 hrs. Airplane performance data indicated that at maximum cruise power, the expected fuel flow would be about 632 lbs./hr., resulting in an endurance of approximately 2.7 hrs. At maximum range power, the expected fuel consumption was about 406 lbs./hr., resulting in an endurance of approximately 4.2 hrs. Both the pilot and medical crew described a lack of communication and coordination among crew members. The pilot reported that the medical crew became apprehensive as the emergency transpired. On three occasions, as the pilot maneuvered the airplane attempting to locate a hole in the clouds to descend, the medical crew member in the co-pilot seat grabbed the control wheel to keep the pilot from banking the airplane. He subsequently relinquished the control wheel as directed by the pilot. The medical crew attempted to locate the airplane by using cellphones to coordinate with the operator's operations center or by using the cellphone GPS capability. However, these efforts resulted in multiple course adjustments and ultimately failed to encounter visual meteorological conditions before fuel exhaustion on the left engine.
The loss of electrical power due to the pilot’s inadvertent selection of the engine start switches and the subsequent fuel exhaustion to the left engine as the pilot attempted to locate visual meteorological conditions. Contributing to the accident were the pilot’s failure to ensure adequate fuel reserves on board for the flight in instrument meteorological conditions and the miscommunication between the pilot and medical crewmembers.
Source: NTSB Aviation Accident Database
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