Bell 206B N10857

Summary

On 31 July 1989 at about 20:35 local time, a Bell 206B registered N10857, operated by CA. Amer. Research Information, was involved in an accident near Rialto, California, United States. 2 people were 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

31 July 1989 at 20:35

Classification

Accident

Location

Rialto, California, United States

Nearest airport

Rialto Munic. Arpt (L67)

Coordinates

34.1007, -117.3794

Aircraft

Bell 206B

Registration

N10857

Category

Helicopter

Engines

1

Operator

CA. Amer. Research Information

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX89LA253

Nobody was injured.

FAILURE TO INSTALL TWO OF THE FOUR REQUIRED NUTS WHICH RETAIN THE HIGH SPEED COUPLING INPUT DRIVE SHAFT TO THE TRANSMISSION.

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

Read the full NTSB narrative

DURING A PRACTICE AUTOROTATION WITH A POWER RECOVERY, THE FLIGHT INSTRUCTOR HEARD A NOISE FROM THE REAR OF THE HELICOPTER. WHEN THE POWER RECOVERY WAS ATTEMPTED, THE ENGINE RESPONDED TO THE THROTTLE APPLICATION BUT THE LOW RPM WARNING HORN ACTIVATED AND THE HELICOPTER STRUCK THE GROUND IN A LEVEL ATTITUDE WHICH CAUSED THE MAIN ROTOR BLADES TO SEVER THE TAILBOOM. EXAMINATION OF THE HIGH SPEED OUTPUT DRIVESHAFT COUPLING, TRANSMISSION END, SHOWED THAT THE FOUR BOLTS WERE INSTALLED BUT THE FOUR NUTS AND FOUR WASHERS COULD NOT BE FOUND IN THE ASSEMBLY. TWO NUTS WERE FOUND IN THE SCUPPER DRAIN OF THE TRANSMISSION DECK.

Quoted verbatim from the NTSB record.