ASN Wikibase Occurrence # 199511
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| Date: | Tuesday 14 June 2016 |
| Time: | 15:50 |
| Type: |  Bell 206L-1 LongRanger II |
| Owner/operator: | Private |
| Registration: | N1076Y |
| MSN: | 45380 |
| Year of manufacture: | 1980 |
| Total airframe hrs: | 34947 hours |
| Engine model: | Allison 250 C30P |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Bishop, CA -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Corona, CA (AJO) |
| Mammoth Lakes, CA (MMH) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The private pilot departed on a cross-country flight with two passengers onboard the helicopter, which had been filled with 110 gallons of fuel (88 gallons of which were in the aft tank) before departure. The pilot reported that, after encountering headwinds that were about 15 knots greater than anticipated and turbulence for more than 2 hours, he saw that the helicopter was low on fuel and decided to land at a nearby airport. He began a descent from 12,000 ft mean sea level (msl), but as he passed through 10,000 ft msl, he heard a “violent explosion in the engine compartment,” followed by the illumination of the engine-out indication light. The pilot immediately initiated an autorotation and made two unsuccessful attempts to restart the engine during the descent. He flared the helicopter at 2,000 ft to avoid settling into a crater, and it subsequently impacted terrain hard. Paint transfer signatures on one of the main rotor blades indicated that they likely contacted and severed the tailboom during landing.
The pilot stated that he did not pull the fuel pump circuit breakers before or during the accident flight; however, the unbreeched aft fuel tank was void of fuel when first responders examined it shortly after the accident, and the fuel pump circuit breakers were found in the “off” position. Further, operational tests of the fuel system and engine did not reveal any blockages or mechanical malfunctions. Fuel computations showed that the engine consumed 88 gallons of fuel, the quantity that would have been in the aft tank at the time of departure, and the pilot reported that he customarily disengages the fuel pumps after each flight. It is likely that the pilot’s improper fuel management, possibly from departing with the fuel pumps in the “off” position, prevented fuel trapped in the forward tanks from reaching the engine and resulted in fuel starvation.
The pilot had planned the flight around 15-knot winds despite multiple weather forecasts issued before his departure that indicated the presence of about 30-knot headwinds along his flight route. It is likely that the pilot’s poor preflight weather and fuel planning resulted in greater-than-anticipated fuel consumption, which led to the low fuel state and the pilot’s decision to divert to a closer airport.
The pilot did not experience any control issues throughout the long autorotation from 10,000 ft, and weather reports indicated that he would not have encountered any visibility restrictions during the descent, so he should have had sufficient time to properly flare the helicopter and land. However, he chose to initiate a flare at 2,000 ft, which likely reduced the rotor rpm and led to hard impact with terrain.
Probable Cause: The pilot’s improper preflight weather planning, fuel planning, and fuel management, which resulted in fuel starvation and a loss of engine power. Contributing to the severity of the accident was the pilot's initiation of the landing flare at a high altitude, which led to a subsequent hard landing.
Accident investigation:
 |
|
Sources:
NTSB
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 08-Sep-2017 19:47 | ASN Update Bot | Added |
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