Bell 206L-3 N741LL

Summary

On 26 July 2005 at about 15:10 local time, a Bell 206L-3 registered N741LL was involved in an accident near Justice, Illinois, United States. 4 people were on board and 2 were seriously injured, 2 had minor injuries. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

26 July 2005 at 15:10

Classification

Accident

Location

Justice, Illinois, United States

Coordinates

41.7500, -87.8353

Aircraft

Bell 206L-3

Registration

N741LL

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Public Use

Phase of flight

Not recorded

Route

Downers Grove → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

CHI05GA198

2 people were seriously injured.

The pilot's improper in-flight decision while maneuvering which resulted in a tailwind during low airspeed helicopter flight and subsequent loss of tail rotor effectiveness. The struck sign and fence were factors in the accident.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The helicopter was destroyed when it impacted a sign, a privacy/guard fence, and the terrain adjacent to an interstate highway. The public use flight was conducted in order to survey a tollway. According to the pilot, the helicopter began, "a sudden right yaw with possibly a raising of the tail. The aircraft then yawed left, possibly in response to pedal input ... Then started what seemed to be a slower right rotation." The helicopter continued to rotate to the right, descended, and impacted the structure of an overhead road sign, a privacy/guard fence and then came to rest on the ground adjacent to the fence. The reported winds in the vicinity of the accident site were 290 degrees at 15 knots. Radar track data showed that the helicopter traveled in a northwesterly direction parallel to an interstate highway, passed a toll plaza, and then began a left turn. The radar data showed that during the left turn, the wind direction relative to the aircraft ground track entered the region defined in the Federal Aviation Administration "Rotorcraft Flying Handbook" (FAA-H-8083-21), as being conducive to weathercock instability. During this same period, the helicopter's calibrated airspeed was between 4 and 20 knots. FAA-H-8083-21 states that, "In this region, the helicopter attempts to weathervane its nose into the relative wind. Unless a resisting pedal input is made, the helicopter starts a slow, uncommanded turn either to the right or left depending upon the wind direction. If the pilot allows a right yaw rate to develop and the tail of the helicopter moves into this region, the yaw rate can accelerate rapidly." FAA-H-8083-21 also states that, "Unanticipated yaw is the occurrence of an uncommanded yaw rate that does not subside of its own accord and, which, if not corrected, can result in the loss of helicopter control. This uncommanded yaw rate is referred to as loss of tail rotor effectiveness (LTE) and occurs to the right in helicopters with a counter-clockwise rotating main rotor." No anomalies were found with respect to the helicopter.

Quoted verbatim from the NTSB record.