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Aviation safety reports, made easier to study

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NTSB Report

November 18, 2018 · Robinson R44 Undesignat · N4167Y

Knox City, TX

Overview

Report Status
Final with probable cause
Event Type
Accident
Date
November 18, 2018
Injury Outcomes
No injuries (4 uninjured)
Location
Knox City, TX
Aircraft
Robinson R44 Undesignat (2008)
Tail Number
N4167Y
Injuries
None
Aircraft Damage
Substantial
NTSB Number
GAA19CA063

The helicopter pilot reported that, while conducting a photography flight about 70 ft above ground level, the helicopter's heading was 190°, and the airspeed was less than 9 knots. With a 10-knot tailwind, the helicopter began to settle with power. The pilot increased the collective and applied forward cyclic to increase the airspeed, but the helicopter continued to settle and impacted the ground hard. The helicopter sustained substantial damage to the main rotor system and fuselage. The pilot reported that there were no mechanical malfunctions or failures with the helicopter that would have precluded normal operation. The pilot reported that the wind about the time of the accident was from the north at 10 knots. According to the Helicopter Flying Handbook, Chapter 11, page 11-10 When recovering from a settling with power condition, the pilot tends first to try to stop the descent by increasing collective pitch. However, this only results in increasing the stalled area of the rotor, thereby increasing the rate of descent. Since inboard portions of the blades are stalled, cyclic control may be limited. Recovery is accomplished by increasing airspeed, and/or partially lowering collective pitch. In many helicopters, lateral cyclic combined with lateral tailrotor thrust will produce the quickest exit from the hazard assuming that there are no barriers in that direction. In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state.

NTSB Probable Cause

The pilot's failure to maintain adequate airspeed with a tailwind, which resulted in the helicopter settling with power, and his subsequent incorrect collective application while attempting to recover, which resulted in a loss of helicopter control due to a loss of tail rotor effectiveness.

Full Narrative

The helicopter pilot reported that while conducting a photography flight about 70ft AGL, the helicopter's heading was 190° and the airspeed was less than 9 knots. With a 14-knot tailwind the helicopter began to settle with power. He increased collective and applied forward cyclic to increase the airspeed, but the helicopter impacted the ground. The helicopter sustained substantial damage to the main rotor system and the fuselage. The pilot reported that the wind about the time of the accident was from the north at 14 knots. The pilot reported that there were no mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to the Helicopter Flying Handbook, Chapter 11, page 11-10: When recovering from a settling with power condition, the pilot tends first to try to stop the descent by increasing collective pitch. However, this only results in increasing the stalled area of the rotor, thereby increasing the rate of descent. Since inboard portions of the blades are stalled, cyclic control may be limited. Recovery is accomplished by increasing airspeed, and/or partially lowering collective pitch. In many helicopters, lateral cyclic combined with lateral tailrotor thrust will produce the quickest exit from the hazard assuming that there are no barriers in that direction. In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state.

Flight

Event TypeAccident
Event Time08:30 CST
Nearest Airport0nm
Flight Plan FiledNone
Flight Plan ActivatedNo
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftRobinson R44 Undesignat
Tail NumberN4167Y
Aircraft CategoryHeli
DamageSubstantial
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · O-540-F1B5 · Reciprocating · 235
Seats2

People & Injuries

Injury SummaryNo injuries (4 uninjured)
Fatal0
Serious0
Minor0
Uninjured4
Total4
Crew 1Age 34 · Second Class · None

Conditions

ConditionsVMC
LightDaylight
Wind350° @ 10 kt
Visibility10 sm
CeilingOvercast 3300 ft
Temperature / Dew Point30 C / 23 C
Altimeter30.37 inHg
Observation Time14:53
Weather SourceWFAC

Appendix: Source Data