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Aviation safety reports, made easier to study

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September 2, 2001 · Mcdonnell Douglas 369E · N440TJ

Kemmerer, WY

Overview

Report Status
Final with probable cause
Event Type
Accident
Date
September 2, 2001
Injury Outcomes
No injuries (1 uninjured)
Location
Kemmerer, WY
Aircraft
Mcdonnell Douglas 369E
Tail Number
N440TJ
Operator
Omni Aviation Services
Injuries
None
Aircraft Damage
Substantial
NTSB Number
DEN01LA154

The pilot was transporting bags of seismic equipment by long line to a remote site. While he hovered into the wind waiting for a flagger, the helicopter was struck by a wind gust and started turning right. The pilot applied left pedal, but was unable to stop the rotation. The helicopter struck terrain, breaking off both skid legs, tail rotor blades, and tail rotor gearbox. FAA's Advisory Circular 90-95 defines the loss of tail rotor effectiveness as "a critical, low-speed aerodynamic flight characteristic that can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control." Some of the conditions conducive to LTE include (1) a high power setting, (2) low airspeed, and (3) a tailwind or left crosswind.

NTSB Probable Cause

loss of tail rotor effectiveness while hovering. A contributing factor was the wind gust.

Full Narrative

On September 2, 2001, approximately 1150 mountain daylight time, a McDonnell Douglas 369E helicopter, N440TJ, operated by Omni Aviation of Carencro, Louisiana, was substantially damaged when it collided with terrain while hovering near Kemmerer, Wyoming. The commercial pilot, the sole occupant aboard, was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed for this work use flight being conducted under Title 14 CFR Part 133. The helicopter departed a nearby landing zone approximately 1145. According to the pilot, he was transporting bags of seismic equipment by long line to a remote site. He said while he hovered into the wind and waited for a flagger, "a [wind] gust caused the helicopter to start to turn right." He applied "more left pedal," but was unable to stop the rotation. He jettisoned the external load, lowered the collective control, and attempted to fly out of the condition. He was able to stop most of the rotation but not before the helicopter struck the terrain. Both skid legs, tail rotor blades, and tail rotor gearbox broke off. The left horizontal stabilizer was struck by one of the blades, and the tail boom buckled when it struck the ground. The pilot said the winds were "generally light and variable, with [an] occasional gust." According to FAA's Advisory Circular (AC) 90-95, loss of tail rotor effectiveness (LTE) "is a critical, low-speed aerodynamic flight characteristic that can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control. Some of the conditions conducive to LTE include (1) a high power setting, (2) low airspeed, and (3) a tailwind or left crosswind

Flight

Event TypeAccident
Event Time11:50 MDT
Nearest Airport0nm
Flight Plan FiledNone
Flight Plan ActivatedNo
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftMcdonnell Douglas 369E
Tail NumberN440TJ
Aircraft CategoryHeli
DamageSubstantial
OperatorOmni Aviation Services
Operating RulePart 133
Engines1
Engine TypeTurboshaft
Engine DetailsAllison · 250-C20B · Turboshaft · 420
Seats5

People & Injuries

Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 37 · Second Class · None

Conditions

ConditionsVMC
LightDaylight
Wind160° @ 6 kt
Visibility10 sm
CeilingNone
Temperature / Dew Point43 C
Altimeter30.21 inHg
Observation Time17:35
Weather SourceWFAC

Appendix: Source Data