CEN15FA090

The loss of power to the right engine for reasons that could not be determined during postaccident examination and teardown and the pilot’s failure to properly configure the airplane for single-engine flight.

The pilot was conducting an early morning repositioning flight of the cargo airplane. Shortly after takeoff, the pilot reported to air traffic control that he had "lost an engine" and would return to the airport. Several witnesses reported that the engines were running rough and one witness reported that he did not hear any engine sounds just before the impact. The airplane impacted trees, a wooden enclosure, a chain-linked fence, and shrubs in a residential area and was damaged by the impact and postimpact fire. The airplane had been parked outside for 5 days before the accident flight and had been plugged in to engine heaters the night before the flight. It was dark and snowing lightly at the time of the accident. The operator reported that no deicing services were provided before the flight and that the pilot mechanically removed all of the snow and ice accumulation. The wreckage and witness statements were consistent with the airplane being in a right-wing-low descent but the airplane did not appear to be out of control. Neither of the propellers were at or near the feathered position. The emergency procedures published by the manufacturer for a loss of engine power stated that pilots should first secure the engine and feather the propeller following a loss of engine power and then turn the fuel selector for that engine to "off." The procedures also cautioned that continued flight might not be possible if the propeller was not feathered. The right fuel selector valve and panel were found in the off position. Investigators were not able to determine why an experienced pilot did not follow the emergency procedures and immediately secure the engine following the loss of engine power. It is not known how much snow and ice had accumulated on the airplane leading up to the accident flight or if the pilot was successful in removing all of the snow and ice with only mechanical means. The on-scene examination of the wreckage and the teardown of both engines did not reveal any preimpact mechanical malfunctions or failures. While possible, it could not be determined if water or ice ingestion lead to the loss of engine power at takeoff.

The FAA issued Key Lime Air a Part 135 operating certificate in 1997 to conduct on demand cargo and passenger flights. They also hold a Part 121 certificate for scheduled operations between KAPA, Rocky Mountain Metropolitan Airport (KBJC) Broomfield, Colorado, and Grand Junction (KGJT), Colorado. At the time of the accident, Key Lime Air conducted cargo operations in six states. The corporate headquarters, including training, the Director of Operations, Chief Pilot, and Director of Safety were located in Englewood, Colorado. The FAA Flight Standards District Office in Denver, Colorado managed the operating certificate. The company operated six different make and models of airplane and employed about 35 pilots. Prior to employment, each pilot was required to meet the minimum flight time and experience requirements per the Federal Aviation Regulations for Part 135 operations. Centennial Airport (KAPA), is a public, tower- controlled airport (Class D airspace), at a surveyed elevation of 5,885 feet. Class B, E, and G airspace surround the area immediately outside of the Class D airspace at KAPA. The airport had 3 open runways, runway 17L/35R (10,001 feet by 100 feet, asphalt), runway 17R/35L (7,001 feet by 75 feet, asphalt), and runway 10/28 (4,800 feet by 75 feet, asphalt). The flight control cables for ailerons, the elevator, and rudder were examined. Breaks or points of separation through these cables were consistent with impact damage or wreckage recovery efforts. The impact damage on the right stabilizer was consistent with an impact with the chain link fence post. A film of yellow colored engine oil was located along the entire right side of the empennage including the horizontal and vertical stabilizer. Shop air was applied to the deice air lines. The left horizontal stabilizer boot inflated. The right stabilizer boot was impact damaged and could not be tested. The vertical stabilizer boot inflated. The boots along both wings were impact damaged and could not be tested. The rudder trim was measured at 1.3 inches. When compared to the Cessna Charts, this measurement is considered unreliable/beyond limits. The elevator trim was measured at 1.2 inches on the right and 1.3 inches on the left. The aileron trim was measured at 0.8 inches. When compared to the Cessna Charts, this measurement is considered unreliable/beyond limits. Engine control quadrant - were not restricted or bound in movement. The following measurements were taken: Throttles - L 1 3/4 " up from closed R 2 9/16" up from closed Propellers - L 2 7/16" up from detent R 1 13/16" up from detent Mixture - L 2 3/4 R 1 3/4 rich The fuel selector panel exhibited the following positions: Right engine – "off" Left engine – "left main" Fuel selector valves within the wing assemblies exhibited the following positions: Right engine - "off" Left engine - "left main" Field Engine Examination All 3 blades from the right propeller separated from the propeller hub. The hub was fragmented. The propeller blades were labeled R1, R2, and R3 for identification purposes. Blade R1 exhibited leading edge scoring along the first 2.5" of the blade, and face scoring along the entire span of the blade. Otherwise the blade was visually unremarkable. Blade R2 exhibited scoring along the outboard trailing edge of the blade. Otherwise the blade was visually unremarkable. Blade R3 exhibited scoring on the face of the blade leading edge nicks and was bowed aft and twisted. One blade separated from the left propeller assembly. The propeller hub was impact damaged. The propeller blades were labeled L1, L2, and L3 for identification purposes. Blade L1 exhibited leading edge gouges and nicks. Otherwise the blade was visually unremarkable. BladeL2 was bowed forward. Otherwise the blade was visually unremarkable. Blade L3 separated from the propeller hub and exhibited leading edge gouges and nicks. Otherwise the blade was visually unremarkable. The left engine exhibited exposure to heat and fire and impact damage. The top bank of spark plugs and the valve covers were removed. The spark plugs exhibited worn out normal signatures when compared to Champion spark plug chart. The p-leads were damaged by fire and could not be functionally tested. A lighted bore scope was used to examine the engine through the upper spark plug orifice at each cylinder. The examination revealed no anomalies. The engine was rotated through at the accessory housing. Air movement was noted on all cylinders at the upper spark plug orifice. Valve train continuity was observed on all cylinders. The right engine forward gear case was impact damaged. The intake and exhaust valve arms on the No. 5 cylinder separated. The oil sump was impact damaged. The top bank of spark plugs and valve covers were removed. The spark plugs exhibited worn out normal signatures when compared to Champion spark plug chart. A lighted bore scope was used to examine the engine through the upper spark plug orifice at each cylinder. The examination revealed no anomalies. The engine could not be rotated through by hand. Lab Engine Examination Left engine The vacuum pump was disassembled and no anomalies were noted. The fuel pump spline was intact and the fuel pump rotated without hesitation. Disassembly of the pump revealed no preimpact anomalies. A slave harness was placed on the right magneto and it was operated on a test bench. No spark was noted on any of the leads. Internal heat damage to the capacitor terminals and the points prevented normal operation. Examination of the left magneto revealed similar internal heat damage to the capacitor terminals and the points. Examination of the cylinders, pistons, crankshaft, crankcase, sparkplugs, valves, and other components revealed signatures of exposure to heat and fire and impact damage. No mechanical anomalies were noted that would have precluded normal operation. Right Engine The left and right magnetos were equipped with a slave harness and ran on a test bench. A blue spark was observed on each lead at varying rpm. The vacuum pump was disassembled and no anomalies were noted. The fuel pump spline was intact and the fuel pump rotated. The fuel pump was impact damaged and epoxy was applied at a fitting for bench testing purposes. An additional fitting in the vapor tower was impact damaged and replaced for testing purposes. The fuel pump was installed on a test stand and ran at rpms between 700 and 3,200 for five minutes. The pressure was high and the unit test results were out of limits. Scoring was noted on the rear propeller reduction gear bolt and the aft propeller gear reduction journal. This scoring was consistent with rotation at the time of impact. The intake and exhaust valve rockers were impact damage and separated. Examination of the cylinders, pistons, crankshaft, crankcase, sparkplugs, valves, crank case halves, and other components revealed signatures of impact damage. No mechanical anomalies were noted that would have precluded normal operation. De-Icing Procedures According to Key Lime Air, the method for deicing airplanes is dependent on the extent and thickness of the ice and is left to pilot's discretion for requesting deicing services. Generally pilots will physically remove frost, ice, snow, and surface contaminations. If the contamination is thicker or a jet is being operated the pilot can use chemicals for deicing. The Cessna Pilot Safety And Warning Supplement – Airframe Icing – discusses that the "inflight ice protection equipment is not designed to remove ice, snow or frost accumulation on a parked airplane… Other means … must be employed to ensure that all wing, tail, control, propeller, windshield, static port surfaces and fuel vents are free of ice, snow, and frost accumulations, and that there are no internal accumulations of ice or debris in the control surfaces, engine intakes, brakes, pitot-static system ports,