NTSB Factual Report

On December 7, 2003, at 1541 eastern standard time, a Bell OH-58A, helicopter, N62939, registered to and operated by Hillsborough County Sheriff Department, collided with the ground during an autorotation three miles east of Ruskin, Florida. The public use flight operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The helicopter was substantially damaged. Both commercial pilots were not injured. The flight departed Vandenberg Airport in Tampa, Florida, at 1515, on December 7, 2003.

According to the operator, the flight was dispatched on a routine police call, and was circling the destination area at 500 feet above ground level when the pilot felt a reduction in engine power and noted a split in the rotor and turbine tachometers. After the throttle position was checked, the pilot realized that there was a reduction in engine power as the engine rpm went to idle. The pilot lowered the collective and entered an autorotation at 60 knots. The helicopter collided with the ground in a marshy area in a tail low attitude. The engine continued to run at idle power until the crew shut down the engine using the throttle and fuel valve handle.

The post-accident examination of accident site revealed the wreckage crashed in a densely vegetated and marshy area, three miles east of Ruskin, Florida and 18 miles south of Tampa, Florida. Examination of the aircraft revealed both plexiglas chin bubbles and the right front windscreen were broken, damage to the bottom of the fuselage, one main rotor blade was severed three and a half feet from blade-retaining bolt, both pitch change links fractured, the tail boom was severed just forward of the horizontal stabilizers, one tail rotor blade was bent 90-degrees near the root of blade and the lower leading edge of the aft vertical fin was damaged. It was also noted that all four saddle mounts securing the skids to the cross tubes were fractured, the rotating swash plate contacted and damaged the particle separator fairing aft of the main transmission and the engine to transmission drive shaft exhibited a bend of 10-degrees.

Examination of the engine revealed no anomalies in the general physical condition and security of the engine as it was mounted in the accident helicopter. There was no fuel present in the lines to the fuel nozzle as the engine was manually shut down using the throttle and main fuel shut-off valve following impact and the engine exhibited continuity and freedom of movement in the N1 and N2 drive trains through the accessory gearbox. King Laboratories in Tampa, Florida tested the fuel samples both from the helicopter and the tank from which the helicopter was refueled. The samples were determined to be in compliance with the standards established for Jet A fuel. The first five attempts to conduct a functional test-run of the engine were unsuccessful and the original fuel control was replaced. On the sixth attempt, the engine ran without issue. The power turbine governor and fuel control were bench tested at the Honeywell facility and no pre-existing conditions were identified that would have prevented normal operation in either assembly. An additional engine run with the original fuel controls installed was performed at the Rolls-Royce plant and again, the engine ran without irregularities and nearly to performance standards for new production engines.

NTSB Probable Cause

Loss of engine power due to undertermined reasons which resulted in a collision with terrain.