ASN Wikibase Occurrence # 133285
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| Date: | Saturday 30 January 1999 |
| Time: | 16:43 LT |
| Type: |  McDonnell Douglas MD 500E (369E) |
| Owner/operator: | Riverside County Sheriff Dept. |
| Registration: | N992SD |
| MSN: | 510E |
| Year of manufacture: | 1993 |
| Total airframe hrs: | 4093 hours |
| Engine model: | Allison 250-C20B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Lake Elsinore, CA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Unknown |
| Departure airport: | Hemet, CA (KHMT) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
While the pilot was maneuvering about 550 to 650 feet agl, the engine chip light illuminated followed by a complete loss of engine power. She performed an autorotation to a large, open field, flared high about 100 feet agl, then collided with the ground. The skids were found spread outward with the belly touching the ground. Two of the main rotor blades displayed evidence of coning. Post-accident investigation revealed that all components of the lubrication system were intact and functional. When the turbine was disassembled, bearings 6 through 8 were found destroyed and displayed evidence of heat distress and oil starvation. The number 5 bearing evidenced heat distress. The nos. 1 through 5 bearings and the gearbox were lubricated, but there was no visual evidence of oil present downstream from the number 5 bearing. There was scoring and debris present in the oil pump scavenge chamber. Over a period of about 72 flight hours and 1 1/2 months, there were 10 reported engine chip light activations. After three chip lights were reported, the turbine, gear box, and compressor assembly were replaced. Engine chip lights were reported six more times. The number 5 bearing and snap ring were found spinning; a new number 5 bearing was installed. The day of the accident, the chip light came on during a maintenance ground run, then came on again before the engine quit. According to the Allison Engine Operation and Maintenance Manual, 'a maximum of four occurrences of magnetic chip warning lights encountered within any 50 hours of engine operation requires removal of the engine for shipment to an Allison Authorized Maintenance Center (AMC).'
Probable Cause: The pilot's failure to maintain main rotor rpm and her misjudged flare. Also causal was the failure of the company maintenance personnel to follow the procedures/directives in the engine manufacturer's operation and maintenance manual and their improper inspection of the engine. A factor was the oil starvation of the nos. 6, 7, and 8 bearings that resulted in a total loss of engine power.
Accident investigation:
 |
|
Sources:
NTSB LAX99GA083
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 21-Dec-2016 19:26 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 25-Nov-2017 12:49 | ASN Update Bot | Updated [Cn, Operator, Nature, Departure airport, Destination airport, Source, Narrative] |
| 14-Dec-2017 16:56 | ASN Update Bot | Updated [Cn, Operator, Departure airport, Destination airport, Narrative] |
| 30-May-2023 01:52 | Ron Averes | Updated [[Cn, Operator, Departure airport, Destination airport, Narrative]] |
| 08-Apr-2024 10:17 | ASN Update Bot | Updated [Time, Cn, Operator, Other fatalities, Nature, Departure airport, Source, Narrative, Accident report] |
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