Boeing Vertol 107 N6676D

Summary

On 14 October 1982 at about 20:18 local time, a Boeing Vertol 107 registered N6676D, operated by Columbia Helicopters, Inc., was involved in an accident near Cascade, Idaho, United States. 2 people were on board and 2 died. The aircraft was destroyed. No probable cause statement is available for this record.

Date

14 October 1982 at 20:18

Classification

Accident

Location

Cascade, Idaho, United States

Coordinates

44.5891, -115.5707

Aircraft

Boeing Vertol 107

Registration

N6676D

Category

Helicopter

Engines

2

Operator

Columbia Helicopters, Inc.

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Cascade → Cascade

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

SEA83FA009

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

DURING A LOG SLINGING OPERATION A LOUD BANG WAS HEARD & THE ACFT WAS OBSERVED TO RAPIDLY DESCEND VERTICALLY TO THE GROUND WITH NUMEROUS SMALL FRAGMENTS FALLING IN THE SAME VICINITY. THE #5 SYNCHRONIZATION SHAFT WAS FOUND TO BE FRACTURED AT THE FORWARD END ABOUT 9 INCHES AFT OF THE CONNECTION ASSY TO THE #4 SHAFT. THIS RESULTED IN AN OUT OF SYNCHRONIZATION CONDITION BETWEEN THE FORWARD & AFT ROTOR BLADES AS WELL AS A LOSS OF POWER TO THE FORWARD ROTOR. A FATIGUE FRACTURE ORIGINATED IN THE AFT MOST RING OF RIVET HOLES. THE FATIGUE CRACKS PROPOGATED FROM MULTIPLE ORIGINS WITHIN THOSE RIVET HOLES WHERE A "STEP" WAS FOUND AT THE BASE OF THE HOLE & CLOSEST TO THE INSIDE DIAMETER OF THE SHAFT.ALL RIVET HOLES IN THE FORWARD END OF THE SHAFT HAD TOPOGRAPHIC FEATURES SIMILAR TO THOSE PRODUCED IN A STEEL PLATE BY DELIBERATELY DRILLING HOLES WITHOUT COMPLETE PENETRATIONS.

Quoted verbatim from the NTSB record.