ASN Wikibase Occurrence # 291728
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| Date: | Wednesday 11 October 2006 |
| Time: | 11:00 LT |
| Type: |  Hughes OH-6A |
| Owner/operator: | Private |
| Registration: | N810SB |
| MSN: | 580468 |
| Year of manufacture: | 1967 |
| Engine model: | Allison T63A-700 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Key Largo, Florida -
 United States of America
|
| Phase: | Unknown |
| Nature: | Private |
| Departure airport: | Key Largo, FL (O7FA) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: The pilot's inadvertent encounter with a loss of tail rotor effectiveness during hover in a crosswind wind.
Accident investigation:
 |
|
Sources:
NTSB MIA07CA004
History of this aircraft
Other occurrences involving this aircraft
| 19 May 2018 | N369GK | Private | 0 | 4 mls N of Stoneburg, TX | |
w/o |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 07-Oct-2022 18:14 | ASN Update Bot | Added |
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