Bell 47G N951B

Summary

On 9 May 1985 at about 18:30 local time, a Bell 47G registered N951B was involved in an accident near Calwood, Missouri, United States. 2 people were on board and 2 died. The aircraft was destroyed. No probable cause statement is available for this record.

Date

9 May 1985 at 18:30

Classification

Accident

Location

Calwood, Missouri, United States

Coordinates

38.8806, -91.7605

Aircraft

Bell 47G

Registration

N951B

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Columbia → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

MKC85FA100

2 people died.

The NTSB has not published a probable cause for this record. No probable cause statement is present in the source data.

Nothing about the cause is stated here that is not in the source record.

Read the full NTSB narrative

N951B CRASHED IN A WOODED AREA DURING A POWERLINE PATROL FLT WHICH INCLUDED PHOTOGRAPHY OF THE POWERLINE. ACCORDING TO WITNESSES, THE HELICOPTER WAS FLYING PARALLEL TO THE POWERLINE IN A WESTERLY DIRECTION WHEN THE ACCIDENT OCCURRED. EXAM OF THE WRECKAGE REVEALED THE TAIL ROTOR GEAR BOX AND HUB, ALONG WITH ON TAIL ROTOR BLADE HAD SEPARATED IN FLT AND WAS LOCATED APRX 50 YARDS FROM THE MAIN WRECKAGE. THE OTHER TAIL ROTOR BLADE WAS LOCATED APRX 160 YARDS AWAY FROM THE MAIN WRECKAGE. METALLURGICAL EXAM OF THE BROKEN YOKE REVEALED A FATIGUE FRACTURE WHICH PROGRESSED FROM MULTIPLE ORIGINS AT THE ROOT OF THE INTERNAL THREADS OF THE SPLINE. THE EXAM ALSO SHOWED THAT THE INTERNAL THREADS WERE NITRIDE TREATED. THIS WAS NOT A BELL HELICOPTER PART. THE PMA, UNDER WHICH THIS PART WAS MANUFACTURED, PROHIBITS NITRIDE TREATMENT OF THE SPINDLE BORE & THREADS.

Quoted verbatim from the NTSB record.