Bell 206B3 N2763R

Summary

On 4 May 2006 at about 16:30 local time, a Bell 206B3 registered N2763R was involved in an accident near Fallbrook, California, United States. 2 people were on board and 2 had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

4 May 2006 at 16:30

Classification

Accident

Location

Fallbrook, California, United States

Coordinates

33.4333, -117.2500

Aircraft

Bell 206B3

Registration

N2763R

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Fallbrook → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX06LA161

2 people had minor injuries.

Failure of the engine to transmission drive shaft forward coupling due to overheating from lack of lubrication. The cause of the lack of lubrication was a result of improper maintenance. A factor was the trees.

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

Read the full NTSB narrative

The helicopter collided with trees following a failure of the engine to transmission drive shaft. After finishing a final rinse load for the agricultural spray operation, the pilots began the short return flight back to a trailer. While maneuvering about 20 feet above ground level (agl), and about 5 feet above the treetops, the helicopter made an uncommanded yaw and settled into the trees. A post accident examination revealed that the engine to transmission drive shaft (short shaft) was separated at the forward coupling flange, adjacent to the transmission. Investigators removed the rust-covered engine to transmission drive shaft forward coupling from the gear. The retainer ring, packing seal, and drive shaft coupling seal were not attached to the coupling and dangling loosely on the drive shaft tube. A visual examination of the internal coupling revealed that grease retainer plate had a shiny polished appearance from the gear sprocket making repetitive contact with its surface. The engine to transmission drive shaft forward gear sprocket teeth were not present, as a result of overheating and persistent contact, which had worn them smooth. On the face of the gear sprocket there was a semicircular indentation that had the shape and dimension consistent with that of a partial impression of the spring that is normally inside the coupling. Pieces of the spring were found deformed in the aft coupling housing. There was no evidence of grease in the forward coupling, and the aft coupling contained grease that was dirty and black. The operator's component card record for the engine to transmission drive shaft indicated that it was last inspected about 2 months prior to the accident at which time a mechanic repacked the couplings with grease. The helicopter's applicable Maintenance Manual indicated that every 600-hour or 12-month period (whichever occurs first) the main drive shaft component should be inspected.

Quoted verbatim from the NTSB record.