Aerospatiale SA 316B N146RM

Summary

On 28 November 1991 at about 07:21 local time, a Aerospatiale SA 316B registered N146RM, operated by Rocky Mountain Helicopters, was involved in an accident near Bridgeport, California, United States. 4 people were on board and 4 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

28 November 1991 at 07:21

Classification

Accident

Location

Bridgeport, California, United States

Coordinates

38.2706, -119.3297

Aircraft

Aerospatiale SA 316B

Registration

N146RM

Category

Helicopter

Engines

1

Operator

Rocky Mountain Helicopters

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Bridgeport → Reno

Aircraft damage

Destroyed

Weather

VMC

Light

Night/Dark

NTSB number

LAX92FA054

4 people died.

FAILURE OF THE HELICOPTER'S TAIL ROTOR DRIVE SHAFT AND DRIVE SHAFT BEARING DUE TO UNDETERMINED REASON(S).

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

Read the full NTSB narrative

THE AEROMEDICAL EVACUATION (EMS-MEDEVAC) FLT WAS MADE AT NGT OVR MTN TRRN. THE PLT INTERRUPTED HIS NORMAL PSN RPRT & BROADCAST 'MAYDAY' 3 TIMES, GIVING HIS PSN TO A COMPANY DISPATCHER. HE DID NOT STATE THE NATURE OF THE EMERGENCY. NO FURTHER COMM WAS RECORDED. WITNESSES IN A SOUTHBOUND AUTO SAW THE HELICOPTER FLYING TOWARD THEM FROM THE SOUTH. THEY STATED THE HELICOPTER'S FUSELAGE STARTED ROTATING COUNTER-CLOCKWISE. IT THEN VEERED TO THE WEST, WENT OUT OF SIGHT, AND CRASHED. ALL MAJ COMPONENTS, EXCEPT ABOUT 33 INCHES OF THE TAIL ROTOR DRIVE SHAFT & ITS #5 BRG, WERE LOCATED. THE TAIL BOOM WAS FOUND IN 3 SECTIONS. ROTATIONAL & LONGITUDINAL SCORING DAMAGE WAS NOTED ON THE TAIL BOOM IN THE VCNTY OF THE #3 & #5 BRG SUPPORTS. A LAB RPRT STATED THAT THE ROTATIONAL DMG OCCURRED BEFORE THE GROSS DEFORMATION OF THE TAIL BOOM & SUBSEQUENT IN-FLT BREAKUP OF THE HELICOPTER.

Quoted verbatim from the NTSB record.