ANC06LA064

NTSB accident investigation · Robinson R44 · Skwentna, AK · May 30, 2006

Accident · No injuriesLimited investigationFinal report
Date
May 29, 2006, 19:20 local (May 30, 2006, 03:20 UTC)
Place
Skwentna, AK
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N688JKRobinson R44
Weather
Visual (VMC) · Day
Status
Completed · report February 26, 2007
Report
Approved by Office Director
NTSB office
Alaska Regional Office
Parties
FAA, Anchorage Flight Standards District Office
FAA report
20060529012089A
Case key
63778

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 rigging of the external sling load, which allowed the suspended load/cargo cable to entangle and disable the tail rotor control, resulting in a loss of control during cruise and an in-flight collision with terrain.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Cargo shiftCruise
Loading of cargo - improperPilot in commandCause
External load cable/hook - entangledCause
Rotor failure/malfunctionCruise
Rotor system,tail rotor blade - snaggedFactor
Loss of control - in flightCruise
Rotorcraft flight control,tail rotor control - inoperative
Forced landingDescent - emergency
In flight collision with terrain/waterDescent - emergency
Terrain condition - ground

Analysis

The commercial certificated helicopter pilot was transporting an external sling load and a passenger from a remote off-airport site on a Title 14, CFR Part 135 on-demand air taxi flight. He stated that after lifting a relatively light load on a short sling line, he transitioned to cruise flight. Shortly after entering cruise flight, he said he inadvertently allowed the cargo and sling line to strike the tail rotor blades. The cargo/cable disabled the tail rotor, and the pilot was unable to maintain control of the helicopter. The helicopter subsequently collided with terrain during the ensuing forced landing. The pilot indicated that there were no preimpact mechanical problems with the helicopter.

Factual narrative

On May 29, 2006, about 1920 Alaska daylight time, a skid-equipped Robinson R44 helicopter, N688JK, operated by Ace Flyers, dba JayHawk Air, Anchorage, Alaska, had a loss of tail rotor effectiveness during an emergency landing, and sustained substantial damage when it collided with terrain, about 17 miles north-northwest of Skwentna, Alaska. The commercial certificated pilot and the sole passenger reported no injuries. The local flight was operating in day visual meteorological conditions as an on-demand, Title 14, CFR Part 135 air taxi flight when the accident occurred.

During a telephone conversation with the NTSB investigator-in-charge (IIC) on May 30, the pilot reported that he was repositioning the passenger and a wire mesh cage from a remote drilling site near Sable Creek to a site nearby on the Kahiltna River. The pilot related that the wire cage was slung underneath the helicopter on a line about 18 feet long. He stated that about a minute after liftoff from the 1,200 feet msl site, following the transition to cruise flight, he looked outside the helicopter to try and see how the load was positioned. He said he could not visually acquire the load, and he suddenly heard an unusual noise and felt a shudder/vibration. He immediately jettisoned the load, and sought an emergency landing site close by. The landing site was a clear area in alder brush, on about a 15 degree slope. The pilot reported that the helicopter continued to vibrate and make unusual sounds as he came to a 2 foot hover over the landing site. When he increased the main rotor pitch with the collective control, the pilot said he stepped on the tail rotor control pedals, but there was "no pedal" and no response from the tail rotor. The helicopter quickly started to rotate, and immediately rolled onto its side as it touched the ground. The pilot stated that it was likely that the load on the tether line somehow struck or interfered with the tail rotor, although he could not see any damage to the tail rotor after landing.

In his written statement to the NTSB, the pilot wrote in the section titled: Recommendation (How Could This Accident Have Been Prevented), "Pilot Error--I allowed a light load to catch the tip of the tail rotors."

Aircraft

Registration
N688JK
Reported as
Robinson R44
Category
Helicopter
Serial number
45012
Engine
Lycoming IO-540AE4/5, 205 horsepower, reciprocating
Damage
Substantial damage
Flight
Part 135
Registered owner
Ace Flyers
Airworthiness certificate
Standard, Normal
Departed
Skwentna, AK
Flight plan
Company 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
61
Injuries
None
Certificate
Commercial
Airplane ratings
Single-engine sea, Single-engine land
Medical
Class 2, With waivers/limitations
Last flight review
May 1, 2006
Seat
Right
Flight hours
8,500 total · 50 in this make and model · 8,440 as pilot in command · 100 in the last 90 days · 50 in the last 30 days · 8 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
Calm
Visibility
100 statute miles
Lowest ceiling
None
Temperature
64 °F

FAA reports on this event · 1

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