ASN Wikibase Occurrence # 238912
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| Date: | Thursday 30 July 2020 |
| Time: | 20:45 LT |
| Type: |  Bell OH-58A-BF Kiowa/Arrow Falcon Exporters OH-5 |
| Owner/operator: | A Farmer Service Corp. |
| Registration: | N901XV |
| MSN: | 40494 |
| Total airframe hrs: | 7299 hours |
| Engine model: | Rolls Royce 250-C20C |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Holtville, Imperial County, CA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Agricultural |
| Departure airport: | Imperial County Airport, CA (IPL/KIPL) |
| Imperial County Airport, CA (IPL/KIPL) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot was performing agricultural operations in the helicopter. He made a normal takeoff and completed three passes over the field being sprayed. As he approached wires, the pilot maneuvered the helicopter into a climb and prepared to make a fourth pass. As he was completing a left turn back to the field, the engine experienced a total loss of power. He performed an autorotation, and during the touchdown, the helicopter collided with haystacks.
Postaccident examination of the engine revealed extensive damage to the aft end of the compressor, the spur adapter gearshaft, and the compressor splined adapter. A material analysis revealed that the compressor splined adapter had failed in fatigue. The failure decoupled the turbine section from the compressor section resulting in the loss of engine power.
The compressor splined adapter failed due to a misalignment of the engine's centerline shafting components that resulted from two separate improper maintenance actions. The first improper maintenance action was the installation of an incorrect number of shims at the interface between the rear compressor diffuser and the accessory gearbox.
The second improper maintenance action was the installation of an incorrect compressor splined adapter; the impeller had been machined to fit a larger diameter (-3) compressor splined adapter: however, a smaller diameter (-1) adapter was installed.
Probable Cause: The total loss of engine power due to the decoupling of the engine's turbine and compressor sections, which resulted from improper maintenance.
Accident investigation:
 |
|
Sources:
NTSB WPR20LA247
FAA register: https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=901XV
History of this aircraft
Other occurrences involving this aircraft
| 3 May 2013 | N911RN | Morris Ag Air | 0 | Somerton, Arizona | |
sub |
| Loss of control | ||||||
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 31-Jul-2020 22:05 | Geno | Added |
| 31-Jul-2020 23:30 | Geno | Updated [Time, Aircraft type, Operator, Departure airport, Source] |
| 31-Jul-2020 23:59 | RobertMB | Updated [Aircraft type, Operator, Location, Nature, Narrative] |
| 01-Aug-2020 01:12 | Geno | Updated [Aircraft type, Registration, Cn, Operator, Source, Narrative] |
| 01-Aug-2020 01:17 | RobertMB | Updated [Cn, Operator] |
| 01-Aug-2020 21:05 | Captain Adam | Updated [Narrative] |
| 08-Sep-2020 12:44 | ASN Update Bot | Updated [Time, Cn, Operator, Departure airport, Destination airport, Source, Narrative] |
| 02-Mar-2021 18:52 | rudy | Updated [Source] |
Corrections or additions? ... Edit this accident description
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