ASN Wikibase Occurrence # 30983
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| Date: | Wednesday 8 April 1998 |
| Time: | 23:00 LT |
| Type: |  Bell OH-58A Kiowa |
| Owner/operator: | San Joaquin Helicopters |
| Registration: | N176SJ |
| MSN: | 70-15556 |
| Year of manufacture: | 1970 |
| Total airframe hrs: | 2518 hours |
| Engine model: | Allison T63-A720 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Huron, California -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Agricultural |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During the initial climb, the pilot noted that the fuel boost pump warning light had flickered on and then off, with a corresponding surge in the engine. Approximately 20 feet agl, engine power was lost and the helicopter impacted the ground. A functional field check of the fuel system was conducted and it was noted that there was a leak in the breakaway valve, which would have allowed air to enter the system. Further examination of the fuel boost pump and breakaway valve revealed that the O-rings were deteriorated. The field inspection further revealed that the inlet shutoff valve arm on the fuel boost pump was bent. According to the manufacturer's overhaul manual, if the inlet shutoff valve arm is bent it may prevent the valve from opening and restrict the fuel flow. According to the component overhaul manuals, the O-ring seals in both the fuel boost pump and the fuel breakaway valve are not required to be inspected during routine inspections and are replaced as on-condition items. A hydro leakage test and performance flow test check was conducted on the fuel boost pump with the original O-rings. The fuel boost pump did not pass the manufacturer's tests. The O-ring seals were replaced with new ones, and the fuel boost pump functioned within manufacturer's limits. The fuel control unit and fuel pump were tested and no discrepancies were found. The fuel nozzle was also tested and flowed within manufacturer's limits. Maintenance records disclosed that the last time the fuel boost pump was worked on was 5 years prior to the accident.
Probable Cause: A loss of engine power due to deteriorated O-ring seals in the fuel boost pump, which allowed air to enter the fuel lines. Factors in the accident were the inadequate manufacturer's inspection criteria for the fuel boost pump O-ring seals and the resulting failure of the operator's maintenance personnel failure to detect the condition.
Accident investigation:
 |
|
Sources:
NTSB LAX98LA134
FAA register: 2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=176SJ
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 07-Apr-2015 22:42 | Dr. John Smith | Updated [Time, Cn, Operator, Total fatalities, Total occupants, Other fatalities, Location, Country, Phase, Nature, Departure airport, Source, Damage, Narrative] |
| 20-Dec-2018 13:41 | liamdaniel98 | Updated [Date] |
| 07-Apr-2024 13:48 | ASN Update Bot | Updated [Time, Cn, Operator, Other fatalities, Phase, Departure airport, Source, Damage, Narrative, Category, Accident report] |
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