N13RFCessna 421C

On June 11, 2018, about 0140 eastern daylight time, a Cessna 421C, N13RF, sustained substantial damage when it was involved in an accident at Plant City Airport (PCM), Plant City, Florida. The airline transport pilot sustained minor injuries and the passenger was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight.

According to the pilot, during the takeoff roll, the airplane did not accelerate adequately, and he elected to abort the takeoff. The airplane continued past the departure end of the runway, across a road, and came to rest in a grass field.

Review of airport surveillance video indicated that the pilot did not activate the airport's pilot-controlled runway lighting before takeoff.

The Pilot's Operating Handbook (POH) Engine Failure During Takeoff checklist (Speed Below 100 knots or Gear Down) stated to "close throttles immediately and brake as required" during an aborted takeoff. The handbook recommended discontinuing the takeoff for rough engine operation, unequal power between engines, and sluggish engine acceleration.

The operator reported that the airplane's gross weight at the time of the accident was 6,870 lbs. At that weight, the airplane's takeoff distance was about 1,673 ft and the accelerate-stop-distance was about 3,040 ft; therefore, about 910 ft of runway should have remained during the aborted takeoff.

According to the POH, the accelerate-stop-distance is defined as, "the distance required to accelerate an airplane to a specified speed and, assuming failure of an engine at that instant that speed is attained, to bring the airplane to a stop." The accelerate-stop distance assumed engine failure at the engine failure speed and idle power and maximum braking after engine failure.

The Pilot's Operating Handbook (POH) Engine Failure During Takeoff checklist (Speed Below 100 knots or Gear Down) stated to "close throttles immediately and brake as required" during an aborted takeoff. The handbook recommended discontinuing the takeoff for rough engine operation, unequal power between engines, and sluggish engine acceleration.

The operator reported that the airplane's gross weight at the time of the accident was 6,870 lbs. At that weight, the airplane's takeoff distance was about 1,673 ft and the accelerate-stop-distance was about 3,040 ft; therefore, about 910 ft of runway should have remained during the aborted takeoff.

According to the POH, the accelerate-stop-distance is defined as, "the distance required to accelerate an airplane to a specified speed and, assuming failure of an engine at that instant that speed is attained, to bring the airplane to a stop." The accelerate-stop distance assumed engine failure at the engine failure speed and idle power and maximum braking after engine failure.

Examination of the accident site by a Federal Aviation Administration inspector revealed that the airplane came to rest upright about 750 ft from the edge of the runway threshold. Skid marks from the braking of both main tires were observed beginning in the runway overrun. Both tires made impressions in the grass and dirt that continued from the end of the runway to the main wreckage.

The fuselage and vertical stabilizer displayed damage consistent with impact with the fences. The nose gear had collapsed, and the flaps were in the retracted position. Both main tires displayed wear consistent with heavy braking. Fuel was observed leaking from the wings at the accident site.

Examination of the airframe and engines revealed braking system and flight control continuity. All the engine components and accessories were present. The crankshafts were manually rotated by hand at the propellers and internal continuity was established through both engines. The combustion chamber of each cylinder was examined using a borescope and normal operational conditions were observed.

The examination revealed that a turbocharger compressor air duct was disconnected from the throttle body component on the No. 1 (left) engine. No other additional anomalies were discovered during the examination that would have precluded normal operation.

The engines were sent to the manufacturer for detailed examination and test runs. The engines were fitted with a test propeller and an oil and fuel source. Additionally, the No. 1 engine was fitted with a temporary starter adapter.

The No. 1 engine started normally and was run at various power settings for several minutes, including at full power, with no anomalies noted. A magneto check revealed no anomalies.

With the turbocharger compressor air duct disconnected from the throttle body, the No. 1 engine was started again and run; a power loss was observed. The manifold pressure indicated data similar to a naturally aspirated (non-turbocharged) engine. When the throttle was initially retarded, the engine rpm increased, consistent with a more efficient fuel/air mixture.

The No. 2 (right) engine initially failed to rotate during start and the starter motor was replaced. During the next attempt, the engine started normally but would only operate while being primed. The engine-driven fuel pump was removed and examined. Examination revealed that the fuel pump was contaminated with water and organic substances, and that its internal components were corroded and seized, which resulted in the fracture of the drive coupling. Assembly holes in the rubber diaphragm were observed. The pump vanes were corroded and frozen to the pump housing. The pump's internal parts were removed, cleaned, reassembled, and the pump was bench tested, during which the pump failed to produce normal pressures and flow. The source of the fuel pump contamination could not be determined.

The engine-driven fuel pump from the No. 1 engine was installed, and the No. 2 engine started normally and was run at various power settings for several minutes, including at full power, with no anomalies noted. The throttle was rapidly advanced from idle to full power, and the engine performed normally with no hesitation, stumbling, or interruption.