ASN Wikibase Occurrence # 133815
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Date: | Thursday 14 May 1998 |
Time: | 18:10 LT |
Type: | Bell 206B |
Owner/operator: | Mike Markov |
Registration: | N90215 |
MSN: | 1698 |
Year of manufacture: | 1975 |
Total airframe hrs: | 13489 hours |
Engine model: | Allison 250-C20 |
Fatalities: | Fatalities: 0 / Occupants: 1 |
Aircraft damage: | Destroyed |
Category: | Accident |
Location: | Temecula, CA -
United States of America
|
Phase: | Initial climb |
Nature: | Agricultural |
Departure airport: | Fallbrook, CA |
Destination airport: | |
Investigating agency: | NTSB |
Confidence Rating: | Accident investigation report completed and information captured |
Narrative:The helicopter departed from the fuel truck and subsequently experienced a partial loss of engine power at about 10 feet above sloping terrain. The aircraft settled and impacted the ground. The pilot stated that the engine was still spooling down as he exited the aircraft. When the engine compressor section was examined, it was determined that the internal compressor case plastic coating was cracked with sections of the plastic missing. Erosion which exceeded the manufacturer's allowable limits was visible through the first four vane stages and was most evident in the lower case half. According to the engine manufacturer, when compressor erosion is unchecked it will eventually result in a fatigue fracture of one of the vanes due to a loss of stiffness. The maintenance manual states that the compressor case should be replaced if any vanes are cracked, broken, or show any evidence of tip rub on the rotor spacer. It further states that corrosion or erosion can cause damage to the compressor blades and vanes that can result in engine failure. The manufacturer specifies inspection intervals of the compressor case should be determined by the operating environment, but in any case, should not exceed 300 hours. The compressor case halves had were replaced in December 1996 and had accumulated approximately 600 hours at the time of the accident. They had not been inspected since being overhauled. The pilot reported that the helicopter had been operating in desert terrain.
Probable Cause: A loss of engine power due to a deteriorated compressor air seal which resulted in the fracture and separation of several stator vanes. Deterioration was not detected as a result of an inadequate maintenance inspection frequency.
Accident investigation:
|
| |
Investigating agency: | NTSB |
Report number: | LAX98LA159 |
Status: | Investigation completed |
Duration: | 1 year and 2 months |
Download report: | Final report |
|
Sources:
NTSB LAX98LA159
Revision history:
Date/time | Contributor | Updates |
21-Dec-2016 19:26 |
ASN Update Bot |
Updated [Time, Damage, Category, Investigating agency] |
07-Apr-2024 12:31 |
ASN Update Bot |
Updated [Time, Operator, Other fatalities, Phase, Departure airport, Source, Narrative, Accident report] |
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