ASN Wikibase Occurrence # 298917
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| Date: | Saturday 3 June 2000 |
| Time: | 14:10 LT |
| Type: |  Bell 212 |
| Owner/operator: | Alpine Helicopters |
| Registration: | CFHDY |
| MSN: | 30594 |
| Year of manufacture: | 1973 |
| Total airframe hrs: | 14816 hours |
| Engine model: | P&W PT6T-3B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | EUGENE, Oregon -
 United States of America
|
| Phase: | Unknown |
| Nature: | Unknown |
| Departure airport: | (KEUG) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During a practice power recovery autorotation to a hover, at about 600 feet AGL, the two pilots heard a loud bang, followed by a severe vibration. The PIC lowered the collective and rolled both throttles off to continue the autorotation to the ground, which landed without further incident. Inspection of the helicopter revealed that the 90-degree gearbox with tail rotors attached had separated from the tail boom. Inspection of the tail rotors revealed that the tip weight in one of the blades was missing. Examination of the blade revealed evidence of adhesive debonding between the adhesive and the spar surface. As a secondary securing method, four countersunk screws are in line chordwise and offset in pairs on each side of the blade. All four screw holes showed no significant evidence of deformation. It was determined that the four countersunk screws were ineffective due to the limited amount of clamping provided by the machining, at the manufacturer, of too large a diameter in the countersunk hole relative to the diameter of the screw head, thus allowing the four secondary load path screws to slip behind the spar, resulting in the tip block separating from the blade. The manufacturer reported that although the bonding adhesive is identified as the primary securing method for the tip block, and the four countersunk screws as the secondary, either method independent of the other is capable of carrying the load.
Probable Cause: Inadequate quality control by the manufacturer during the manufacturing process, which led to the total failure of a fastener, and the separation of the tail rotor blade balance weight. An adhesive debond between the adhesive and the surface was a factor.
Accident investigation:
 |
|
Sources:
NTSB SEA00LA097
History of this aircraft
Other occurrences involving this aircraft
| 11 September 2002 | C-FHDY | Alpine Helicopters | 1 | 20 mi W Pink Mountain, BC |  |
w/o |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 16-Oct-2022 00:17 | ASN Update Bot | Added |
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