Hughes OH-6A N810SB

Summary

On 11 October 2006 at about 16:00 local time, a Hughes OH-6A registered N810SB, operated by Chirstopher H. Kirk, was involved in an accident near Key Largo, Florida, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 October 2006 at 16:00

Classification

Accident

Location

Key Largo, Florida, United States

Nearest airport

Ocean Reef Club Airport (O7FA)

Coordinates

25.3189, -80.2714

Aircraft

Hughes OH-6A

Registration

N810SB

Category

Helicopter

Engines

1

Operator

Chirstopher H. Kirk

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Key Largo → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

MIA07CA004

Nobody was injured.

The pilot's inadvertent encounter with a loss of tail rotor effectiveness during hover in a crosswind wind.

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

Read the full NTSB narrative

The pilot stated that he maneuvered the helicopter to the southeast corner of Ocean Reef so the passenger, a photographer, could take photos of a house at the water's edge. The helicopter was in a steady hover over the water with the nose towards the north. The winds were from his left, from the west, at about 10 knots. There were no abnormalities noted with the helicopter's power. He increased left pedal to bring the nose of the helicopter more into the wind to smoothen it out from the effects of the winds on the tail rotor. Suddenly the helicopter started an un-commanded turn to the right. He applied full left pedal, reduced collective, and initiated forward flight. The helicopter continued the right turn. After several rotations and close to the water he initiated an auto-rotation from about 10 feet above the water. He used collective to cushion the contact with the water. The helicopter came to rest on its right side in about 7 feet of water. The passenger stated that while doing aerial photography at about 150 feet above sea level, the helicopter started spinning and spiraling down. They hit the water soon thereafter. A representative for the helicopter's manufacturer, with FAA oversight, examined the helicopter. No abnormalities were found with the helicopter's flight control system. All damage noted to the helicopter was consistent with a water impact. The FAA Aeronautical Handbook\FAA-H-8083-21-Rotorcraft Flying Handbook\Chapter 11-Helicopter Emergencies\Systems Malfunctions\Unanticipated Yaw\Loss of Tail Rotor Effectiveness states that an 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 is not related to an equipment or maintenance malfunction and may occur in all single-rotor helicopters at airspeeds less than 30 knots. It is the result of the tail rotor not providing adequate thrust to maintain directional control, and is usually caused by either certain wind azimuths (directions) while hovering, or by an insufficient tail rotor thrust for a given power setting at higher altitudes.

Quoted verbatim from the NTSB record.