ASN Wikibase Occurrence # 166005
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Saturday 3 May 2014 |
| Time: | 11:30 |
| Type: |  Bell 407 |
| Owner/operator: | Classic Medical Inc |
| Registration: | N407MH |
| MSN: | 53100 |
| Year of manufacture: | 1997 |
| Total airframe hrs: | 10730 hours |
| Engine model: | Allison 250-C47 |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Lizard Head Pass, San Miguel County, CO -
 United States of America
|
| Phase: | Landing |
| Nature: | Survey |
| Departure airport: | Moab, UT (MOB) |
| Telluride, CO | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial pilot and two flight crewmembers were conducting a search and rescue mission for a local sheriff's department in the helicopter. The pilot reported that, after flying five or six lines of the search grid and while in a right turn to begin flying another line of the grid, the engine noise changed. Immediately thereafter and while the helicopter was 200 ft above ground level, the engine chip detector light illuminated, followed by a full authority digital electronic control degrade light. The pilot started to descend toward an open snow-covered meadow for landing, but the engine rpm degraded, so he initiated an autorotation. The helicopter touched down with little forward airspeed and bounced, and the left skid then became caught on an object under the snow. The helicopter rolled onto its left side and then came to rest.
A postaccident examination of the engine showed that the engine gas producer and power turbine drive train had continuity, but there was resistance to the gas producer and scraping of the power turbine when rotated. Further examination of the engine revealed that the gearbox cover had been modified by a repair, which included an insert being threaded into the oil delivery tube port. The insert was blocking the oil flow to the power turbine thrust (No. 5) bearing, which resulted in the bearing overheating and failing due to the lack of lubrication and the subsequent engine failure. No records were found regarding any repair to the gearbox cover oil delivery tube port.
Probable Cause: The failure of the power turbine thrust (No. 5) bearing due to overheating as a result of oil starvation, which led to the engine failure. Also causal to the accident was an undocumented repair to the gearbox cover oil delivery tube port during which an insert was threaded into the oil delivery tube port that subsequently restricted the oil flow to the power turbine thrust bearing.
Accident investigation:
 |
|
Sources:
NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=407MH
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 05-May-2014 10:17 | Útila | Added |
| 05-May-2014 10:18 | harro | Updated [Aircraft type, Location, Nature, Source] |
| 05-May-2014 22:31 | Geno | Updated [Time, Registration, Cn, Operator, Total occupants, Phase, Source, Damage, Narrative] |
| 06-May-2014 06:13 | Anon. | Updated [Total occupants] |
| 08-Oct-2014 13:51 | TB | Updated [Operator, Location, Departure airport, Destination airport] |
| 12-Aug-2016 17:54 | Aerossurance | Updated [Time, Operator, Location, Source, Narrative] |
| 21-Dec-2016 19:28 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 29-Nov-2017 14:22 | ASN Update Bot | Updated [Operator, Total occupants, Other fatalities, Departure airport, Destination airport, Source, Narrative] |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation