GAA19CA344

NTSB accident investigation · Bell UH 1H · Bethel, AK · June 6, 2019

Accident · No injuriesData collectionFinal report
Date
June 6, 2019, 14:00 local (22:00 UTC)
Place
Bethel, AK
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N4085LBell UH 1H
Defining event
Maneuvering: Loss of engine power (total)
Weather
Visual (VMC) · Day
Status
Completed · report November 6, 2019
Report
Approved by Office Director
NTSB office
General Aviation Accidents
Parties
FAA
FAA report
20190606005969A
Case key
99641

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's improper fuel planning, which resulted in fuel exhaustion and a total loss of engine power, and his improper landing flare during a forced autorotation, which resulted in a hard landing. Contributing to the accident were the inoperative fuel gauge, which was not accurately calibrated, and the pilot’s reliance on the gauge.

Findings · 7

NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.

Planning/preparation: fuel planningPersonnel issues › Task performance · PilotBell UH-1H: 1 caseAll aircraft: 719 casesProbable cause
Fluids: fuelAircraft › Fluids/misc hardware · Fluid levelBell UH-1H: 2 casesAll aircraft: 1,695 casesProbable cause
Performance/control parameters: landing flareAircraft › Aircraft oper/perf/capability · Not attained/maintainedBell UH-1H: 2 casesAll aircraft: 1,285 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · PilotBell UH-1H: 9 casesAll aircraft: 9,295 casesProbable cause
Fuel system: fuel indication systemAircraft › Aircraft systems · Incorrect service/maintenanceBell UH-1H: 1 caseAll aircraft: 30 casesProbable cause
Use of equip/info: use of equip/systemPersonnel issues › Task performance · PilotBell UH-1H: 1 caseAll aircraft: 1,391 casesProbable cause
Fluids: fuelAircraft › Fluids/misc hardware · Inadequate inspectionBell UH-1H: 2 casesAll aircraft: 1,695 cases

Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.

Analysis

The pilot reported that, before departure, he was told the helicopter was topped off with fuel for the multistop flight. He added that he did not verify the fuel quantity but that, when he departed for the last leg about 60 miles from the destination airport, the fuel gauge showed just below 600 lbs of fuel, and he decided to fly at 120 knots with a tailwind. He added that, about 3 miles from the destination airport, the engine lost power. He performed an autorotation, but the helicopter landed hard. The helicopter sustained substantial damage to the tailboom and transmission mounts. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation. The pilot reported that, after landing, the fuel quantity gauge showed that there was about 225 lbs of fuel remaining and that the 20-minute fuel light, which did not illuminate during the flight, illuminated once on the ground. He estimated that the helicopter's fuel burn was about 75 to 80 gallons per hour (gph). The chief pilot, who was also the helicopter's owner, reported that he had refueled the helicopter on uneven terrain before the flight. He filled the tank to the bottom of the filler cap on the left side, which he estimated was about 10 to 15 gallons less than the total fuel capacity of the 210-gallon tank. He estimated that the helicopter burned about 90 gph. He added that there were no open mechanical squawks on the helicopter and that he was not aware of any mechanical issues. The Federal Aviation Administrator inspector who examined the helicopter at the accident site reported that the fuel quantity gauge had been serviced and calibrated earlier in the year but continued to indicate that fuel was onboard even after the helicopter ran out of fuel. The 20-minute low fuel light appeared to be functioning normally.

Factual narrative

The pilot reported that, prior to departure, he was told the helicopter was topped off with fuel for the multi-stop flight. He added that he did not verify the fuel quantity. During the last leg, he departed about 60 miles from the destination airport with just below 600 pounds of fuel and he decided to fly at 120 knots with a tailwind. He added that about 3 miles from the destination airport, the engine lost power. He performed an autorotation but landed hard. The pilot reported that after landing, the fuel quantity gauge read about 225 pounds of fuel remaining and that the 20-minute fuel light which did not illuminate during the flight, illuminated once on the ground. The pilot was unsure if anyone had verified the fuel quantity remaining after landing, but they added about 50 gallons of fuel and continued to the destination airport. He estimated that the helicopter's fuel burn was about 75 to 80 gallons/hour. The chief pilot and owner reported that he had refueled the helicopter, which was on uneven terrain, before the flight. He filled the tank to the bottom of the filler cap on the left side, which he estimated was about 10 to 15 gallons less than total fuel capacity of 210 gallon tank. He estimated that the helicopter burned about 90 gallons/hour. He added that there were no open mechanical squawks on the helicopter and that he was not aware of any mechanical issues. The Federal Aviation Administrator inspector, who examined the helicopter at the accident site, reported that the fuel quantity gauge had been serviced and calibrated earlier in the year, but continued to indicate fuel after the helicopter ran out of fuel. The 20-minute low fuel light appeared to be functioning normally. The helicopter sustained substantial damage to the tailboom and transmission mounts. The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.

Aircraft

Registration
N4085L
Reported as
Bell UH 1H (No Series)
Category
Helicopter
Serial number
68-15655
Built
1968
Engine
Lycoming T53-13, 1,400 horsepower, turbo shaft
Damage
Substantial damage
Flight
External load · Part 133
Operator
Yukon Helicopters Inc
Registered owner
Yukon Helicopters Inc
Airworthiness certificate
Special, Restricted (Special)
Departed
None · Bethel, AK
Destination
BET · Bethel, AK
Flight plan
Company VFR
Equipment
Handheld GPS

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
50
Injuries
None
Certificate
Commercial
Medical
Class 2, Without waivers/limitations
Last flight review
May 12, 2019
Seat
Left
Restraint
3-point
Flight hours
5,275 total · 2,500 in this make and model · 4,795 as pilot in command · 78 in the last 90 days · 62 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Wind
310° at 9 knots
Visibility
10 statute miles
Lowest ceiling
1,600 ft broken
Temperature
52 °F, dew point 43 °F
Altimeter
30.23 inHg
Observed at
PABE, 2 nm away

Docket · 5

The files NTSB released with the investigation on August 9, 2019, on NTSB’s docket system: statements, records, photos and specialists’ reports. 4.1 MB in all.

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.

Other investigations on N4085L · 1

Matched to the same aircraft by N-number and date.