Bell 206B N3298G

Summary

On 10 July 2001 at about 10:30 local time, a Bell 206B registered N3298G, operated by Raco Helicopters, was involved in an accident near Secaucus, New Jersey, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

10 July 2001 at 10:30

Classification

Accident

Location

Secaucus, New Jersey, United States

Coordinates

40.7806, -74.0601

Aircraft

Bell 206B

Registration

N3298G

Category

Helicopter

Engines

1

Operator

Raco Helicopters

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Jersey City → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

NYC01LA168

Nobody was injured.

Under torque of a Thomas coupling self-locking nut for undetermined reasons, which resulted in the loss of the corresponding retaining bolt, and subsequent separation of tail rotor drive shaft segments. A factor was the unsuitable terrain beneath the pilot when the loss of tail rotor occurred.

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

Read the full NTSB narrative

The pilot had just completed a spraying pass, and was heading westbound about 100 feet and 60 mph, parallel to power lines and 15-20 feet above trees. He suddenly felt something "break", and the helicopter started to yaw. The pilot realized that the helicopter had experienced a tail rotor failure, but he didn't want to autorotate into trees. He reduced the throttle slightly, maintained altitude, spun around two to three times, and cleared the trees. He headed for a gravel area and rolled off the throttle, but couldn't stop the spin. He attempted to cushion the landing, but the helicopter hit the ground hard. On-scene examination revealed that the Thomas coupling disc assembly on the aft end of the aft short shaft was twisted and bent, and the tail rotor drive shaft just aft of the coupling was bent and separated, about mid-length. A retaining bolt was missing from the Thomas coupling. The missing bolt and washers were found in the helicopter's tailrotor drive shaft tunnel area, and appeared to be undamaged. The self locking retaining nut for the bolt was not located. Metallurgical review revealed that the Thomas coupling at the aft end of the aft short shaft was missing one of the bolt and nut sets that attached the coupling to the splined adapter at the forward end of the first segment of the tail rotor drive shaft. The forward face of the flange adapter contained a series of rotational scoring and impact marks from contact with the bolt heads and discs. The pattern of damage was consistent with the short shaft rotating around the bolt opposite from the missing bolt. Additional examination of the Thomas coupling and associated components revealed that portions of the normal seating positions for the head of the missing bolt and the washer were relatively free of dirt and grease, and that the bore surface of the hole for the missing bolt in the flanged adapter at the forward end of the first segment contained thread imprint marks.

Quoted verbatim from the NTSB record.