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LET
- Usado para
- loss of tail rotor effectiveness
- Definição1
- Loss of tail rotor effectiveness (LTE), or unanticipated yaw, is a critical, low speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside on its own accord and, if not corrected, can result in the loss of aircraft control. LTE is not related to an equipment or maintenance malfunction and may occur in all single-rotor helicopters with antitorque rotors. The tail rotor does not stall, it becomes inefficient and cannot produce enough thrust to stop the yaw rate. While other factors may influence LTE, it is usually caused by either the effects of certain wind azimuths (direction) while at airspeeds less than 30 knots or allowing excessive yaw rates to develop. Demands on tail rotor thrust increase with increasing gross weight and density altitude. At high density altitudes, hovering ceiling may be limited by tail rotor thrust margin and not necessarily by power available. Such conditions may also be encountered during external lifts. If the load is excessive, the main rotor rpm may decrease, or the antitorque effectiveness of the tail rotor may be exceeded resulting in an uncontrolled yaw.
- Fonte1
- INTERNATIONAL CIVIL AVIATION ORGANIZATION. Manual of aircraft accident and incident investigation. Montreal, 2014. (Doc. 9756)
- Definição2
- 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 and to the left in helicopters with a clockwise main rotor rotation.
- Fonte2
- FEDERAL AVIATION ADMINISTRATION. Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA, 2000.
- Contexto
- Before starting, determine the appropriate airspeed and altitude combination to remain out of the cross-hatched or shaded areas of the height-velocity diagram. Additionally, be aware of crosswind conditions that could lead to loss of tail rotor effectiveness. Pick out two references directly in front of the helicopter for the ground path desired. These reference points should be kept in line throughout the maneuver.
- 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 and to the left in helicopters with a clockwise main rotor rotation.
- Subárea1
- Rotorcraft
- Português
- perda de eficiência do rotor de cauda