ASN Wikibase Occurrence # 353262
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| Date: | Saturday 29 May 1999 |
| Time: | 14:00 LT |
| Type: |  Beechcraft D45 |
| Owner/operator: | Travis AFB Aero Club |
| Registration: | N20869 |
| MSN: | BG-100 |
| Total airframe hrs: | 9169 hours |
| Engine model: | Continental O-470-4A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Lake Berryessa, CA -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Travis Afb, CA (8Q0) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The purpose of the flight was to fly over the lake with the intent of viewing the lake and surrounding area. The lake is 10 miles from the airport. Approximately 30 minutes into the flight the pilot noted a loss of fuel pressure followed by a rough running engine. He believed that the engine driven fuel pump had failed. He engaged the electric boost pump and the fuel pressure came back on-line and engine ran normally. The pilot decided to return to the airport to make a precautionary landing. He again noted that the fuel pressure gage needle began to move sporadically and the engine began to run rough and subsequently lost power. He made an unsuccessful attempt to restart the engine utilizing the in-flight engine failure checklist and subsequently ditched the airplane in the lake. No discrepancies were noted with the flight prior to the loss of engine power. The fuel system was inspected with no foreign debris found. A functional check was performed on the electric boost pump and no fuel flow output was observed; however, during the test the pump shorted out. Both the engine driven fuel pump and electric boost pump were sent out for further tests. Two functional checks were conducted on the engine driven fuel pump. An adjusting nut on the engine driven fuel pump allows for an increase or decrease in fuel flow. The first test was completed in the as-received condition with the adjusting nut loose. The results were consistently low, but fuel flow output was observed from the pump. The adjusting nut was then readjusted to overhaul specifications for the second functional check. The check revealed that the fuel flow was within overhaul specifications. During the teardown of the electric boost pump, it was noted that the bearings were loose allowing the pump vanes to rub up against the throat of the pump, decreasing fuel flowing through the fuel system.
Probable Cause: Loss of engine power due to a loose adjustment nut on the engine driven fuel pump that allowed for a decrease in fuel flow and fuel pressure, and the subsequent failure of the electric fuel boost pump due to loose bearings decreasing fuel flow and fuel pressure to sustain engine power.
Accident investigation:
 |
|
Sources:
NTSB LAX99LA202
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 09-Mar-2024 12:08 | ASN Update Bot | Added |
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