Bell UH-1B N91281

Summary

On 16 July 2002 at about 13:30 local time, a Bell UH-1B registered N91281 was involved in an accident near Lorida, Florida, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

16 July 2002 at 13:30

Classification

Accident

Location

Lorida, Florida, United States

Coordinates

27.3100, -81.1117

Aircraft

Bell UH-1B

Registration

N91281

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Lorida → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

MIA02LA133

1 person was seriously injured.

The pilot's continued operation with known engine anomalies resulting in loss of engine power due to failure of the engine fuel control pump drive clutch assembly due to wear and collision with the terrain during the resultant descent.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot stated he was making a spray turn at the south end of a grove and when he started to initiate the turn and pull a little power, he heard a noise, not a real loud boom, just a noise. The helicopter yawed a little bit and lost all lift. It just fell straight down. He didn't have time to look at instruments or anything, it just came straight down like a rock. The ground crew for the spray operation stated they had just refueled the helicopter and put chemical in the tank prior to the pilot departing. A short time later they heard the pilot call on the radio that he had crashed. They went searching and found the helicopter and pilot at the south end of the grove. As they approached the helicopter, the main rotor was still turning and the engine was still running. The pilot was still in the cockpit. They attempted to shut down the engine with the cockpit controls but they were jammed. They then went to the engine compartment and shut the engine off with the fuel control lever. The pilot reported to them that he was attempting to come out of a turn and the engine lost power and the helicopter went down. One of the ground crewmembers reported that the pilot stated during the previous servicing stop that the engine was running hot and losing power. Post accident examination of the engine fuel control showed the pump drive clutch assembly was fractured into two pieces. According to the technician performing the disassembly this resulted in disengagement from the N1 flyweight assembly. The N1 flyweight assembly drives the N1 servo system during normal fuel control operation. The N1 servo assembly determines the amount of fuel supplied to the engine based on the speed at which it is driven. With the N1 servo system effectively disengaged from the fuel control, the system would remain in the start position and the amount of fuel supplied would not be enough to sustain normal engine operation. The technician further stated the pump drive clutch, the mating surface on the flyweight assembly and the bearing located below the drive clutch exhibit excessive wear. The failure of the pump drive clutch can be attributed to this wear. This type of wear occurs over an extended period of operation and is not usually caused by one incident or a sudden impact.

Quoted verbatim from the NTSB record.