ASN Wikibase Occurrence # 42443
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Date: | Thursday 14 October 1982 |
Time: | 14:18 |
Type: | Boeing Vertol 107-II (CH-46) |
Owner/operator: | Columbia Helicopters |
Registration: | N6676D |
MSN: | 6 |
Total airframe hrs: | 2343 hours |
Engine model: | GE CT-58-140 |
Fatalities: | Fatalities: 2 / Occupants: 2 |
Aircraft damage: | Destroyed |
Category: | Accident |
Location: | Cascade, ID -
United States of America
|
Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
Nature: | External load operation |
Departure airport: | Cascade, ID |
Destination airport: | local |
Investigating agency: | NTSB |
Confidence Rating: | Accident investigation report completed and information captured |
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. CAUSE:
Sources:
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020917X05130 Revision history:
Date/time | Contributor | Updates |
24-Oct-2008 10:30 |
ASN archive |
Added |
09-Jan-2011 15:35 |
TB |
Updated [Time, Aircraft type, Other fatalities, Nature, Destination airport, Source] |
10-Jan-2011 05:38 |
TB |
Updated [Aircraft type] |
21-Dec-2016 19:24 |
ASN Update Bot |
Updated [Time, Damage, Category, Investigating agency] |
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