ANC15CA012

NTSB accident investigation · Bell 206B · Palmer, AK · March 10, 2015

Accident · No injuriesData collectionFinal report
Date
March 10, 2015, 15:00 local (23:00 UTC)
Place
Palmer, AK
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N86TABell 206B
Defining event
Maneuvering-hover: Loss of control in flight
Weather
Visual (VMC) · Day
Status
Completed · report July 8, 2015
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA
FAA report
20150310003009A
Case key
90851

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 failure to maintain control while hovering at a low altitude, which resulted in an impact with frozen lake ice. Contributing to the accident was the pilot's decision to operate the helicopter from the left seat contrary to the rotorcraft flight manual, and the decision to continue the flight after the initial impact.

Findings · 4

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.

Performance/control parametersAircraft › Aircraft oper/perf/capability · Not attained/maintainedBell 206B: 10 casesAll aircraft: 1,269 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · PilotBell 206B: 45 casesAll aircraft: 9,295 casesProbable cause
Knowledge: knowledge of proceduresPersonnel issues › Experience/knowledge · PilotBell 206B: 1 caseAll aircraft: 41 casesProbable cause

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 solo helicopter pilot was flying a turbine-powered helicopter, equipped with dual controls, while seated in the left seat. A limitation in the rotorcraft flight manual states, in part: "the minimum flight crew consists of one pilot who shall operate the helicopter from the right crew seat." The N2 governor linear actuator control switch is located on the collective control for the right crew seat only. The pilot reported that flying the helicopter from the left seat and in order to manipulate this control switch, he had to take his left hand off the collective control for the left crew seat, and place it on the left crew seat cyclic control, then take his right hand off the left crew seat cyclic control and place it on the collective control for the right crew seat. The pilot said that while in a 6-foot hover above a frozen lake, he became distracted while adjusting the N2 (rotor) rpm using the linear actuator control switch, and the helicopter became unstable and it began to rapidly descend. He attempted to recover from the unstable condition, but the helicopter's skids struck the ice. After the impact, he was able to recover and regain a stable hover above the ice. Believing that just the helicopter's skids were damaged during the impact, the pilot elected to return to his departure airport, about 19 miles away, where emergency services would be available. During the return flight, as the helicopter climbed to about 50 feet above the ground, all engine power was lost. The pilot entered an emergency autorotation and selected an area of snow-cover as an emergency landing site. The pilot's postaccident inspection of the helicopter revealed that during the initial impact on the frozen lake, the aft landing gear cross-tube assembly had been crushed into the aft portion of the fuselage, which subsequently ruptured the fuel cell, resulting in the loss of all fuel onboard. The pilot stated there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation.

Factual narrative

The solo helicopter pilot was flying a turbine-powered helicopter, equipped with dual controls, while seated in the left seat. A limitation in the rotorcraft flight manual states, in part: "the minimum flight crew consists of one pilot who shall operate the helicopter from the right crew seat." The N2 governor linear actuator control switch is located on the collective control for the right crew seat only. The pilot reported that flying the helicopter from the left seat and in order to manipulate this control switch, he had to take his left hand off the collective control for the left crew seat, and place it on the left crew seat cyclic control, then take his right hand off the left crew seat cyclic control and place it on the collective control for the right crew seat. The pilot said that while in a 6-foot hover above a frozen lake, he became distracted while adjusting the N2 (rotor) rpm using the linear actuator control switch, and the helicopter became unstable and it began to rapidly descend. He attempted to recover from the unstable condition, but the helicopter's skids struck the ice. After the impact, he was able to recover and regain a stable hover above the ice. Believing that just the helicopter's skids were damaged during the impact, the pilot elected to return to his departure airport, about 19 miles away, where emergency services would be available. During the return flight, as the helicopter climbed to about 50 feet above the ground, all engine power was lost. The pilot entered an emergency autorotation and selected an area of snow-cover as an emergency landing site. The pilot's postaccident inspection of the helicopter revealed that during the initial impact on the frozen lake, the aft landing gear cross-tube assembly had been crushed into the aft portion of the fuselage, which subsequently ruptured the fuel cell, resulting in the loss of all fuel onboard. The pilot stated there were no preaccident mechanical malfunctions or anomalies that would have precluded normal operation.

Aircraft

Registration
N86TA
Reported as
Bell 206B (B)
Category
Helicopter
Serial number
1647
Built
1975
Airframe hours
8,367
Engine
Allison 250-C20B, 420 horsepower, turbo shaft
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Lee John S
Registered owner
Lee John S
Airworthiness certificate
Standard, Normal
Last inspection
Annual · November 14, 2014
Departed
PAAQ · Palmer, AK
Destination
PAAQ · Palmer, AK
Flight plan
VFR

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
69
Injuries
None
Certificates
Airline transport, Flight instructor
Airplane ratings
Single-engine land, Single-engine sea, Multi-engine land
Instrument ratings
Helicopter
Medical
Class 3, Waiver time limited special
Last flight review
September 22, 2014
Seat
Left
Restraint
4-point
Flight hours
14,190 total · 1,200 in this make and model · 12,000 as pilot in command · 50 in the last 90 days · 15 in the last 30 days

Weather

Conditions
Visual (VMC) · Day
Wind
160° at 4 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
16 °F, dew point -4 °F
Altimeter
30.14 inHg
Observed at
PAAQ, 19 nm away

Docket · 2

The files NTSB released with the investigation on June 24, 2015, on NTSB’s docket system: statements, records, photos and specialists’ reports. 968 KB 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 N86TA · 1

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