直升机教员手册 Helicopter Instructor’s Handbook
时间：2014-11-10 08:35来源：FAA 作者：直升机翻译 点击：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. With the helicopter engulfed in the cloud of a suspended particulate material, the pilot loses outside reference and horizon cues. The instructor should stress that the loss of pilot visual reference to a fixed point inevitably causes some degree of unintended pilot or aircraft-induced drift away from the intended line of approach and landing. Discuss how, given the top-heavy nature of most helicopters and the aerodynamics of their rotor disks, landing with lateral drift of any kind can cause the aircraft to be damaged, or to roll over, particularly if combined with a pivot point (such as a rock, or rut) upon touchdown. Emphasize the importance of avoiding sideways motion, which can lead to dynamic roll. While the majority of mishaps related to brownout conditions occur during landings, advise the student that a helicopter takeoff may also cause brownout due to rotor wash. Ask the student to explain why it is less problematic during takeoff. The student should explain that the aircraft is accelerating away from the dust, and lateral drift is less of a safety factor, except for obstructions in close proximity to the line of departure. The pilot is able to set a power and nose attitude and fly the aircraft safely out of a zone, and not be overly concerned with induced drift due to restricted visibility. A maximum performance takeoff should be used when taking off from a possible brownout/whiteout condition to ensure the quickest exit possible. If the surface is sand or snow covered, planning for an approach to the surface and being slightly faster than normal should help the pilot avoid a brown or white out. Likewise, the takeoff in a possible white or brown out condition should be from the surface and not from a hover in order to exit the condition before the horizon is completely obscured. Highlight the need to first check the helicopter for clearance from the surface by bringing it light on the skids or skis to ensure power is good, controls are normal, and the landing gear is free, then reducing power to allow the air to clear before the actual takeoff. The standard 40-knot takeoff attitude is very important to heed to stay ahead of the majority of the cloud dust/snow cloud that is generated by the rotor system and maximum power to climb out of the surface obscuration as soon as possible. Instructors should note the experience level of the students being flown. Do not use instrument flight terms with students who have yet to conduct instrument flight training. System or Equipment Malfunctions Antitorque System Failure NOTE: Many helicopters have antitorque failure procedures that can be safely practiced and will most likely terminate the landing with some sort of run on landing. An antitorque failure can occur in several different forms. Impress upon the student the necessity to become familiar with each type of failure, its effects on flight, and the manufacturer’s recommended procedure for coping with the malfunction. A discussion of some of the types of malfunctions, as well as probable effects and corrective actions, should be included in any training syllabus. The instructor should also include discussion on the effects of structural design and components. The vertical stabilator, for example, provides a streamlining or trim effect under certain conditions and airspeeds. At what speeds will the vertical fin be most effective, and does that correlate to touchdown airspeed for the respective RFM procedure? An instructor’s role is greater than regurgitating already printed information. Go beyond the print and incorporate aircraft specifics and procedures to probable conditions that will help the student obtain a higher level of understanding. Complete Loss of Tail Rotor Thrust Ensure the student understands that complete loss of tail rotor thrust involves a break in the drive system, and pedal input will have no effect on helicopter trim. The tail rotor is providing no thrust to compensate for torque. Fixed Pitch Settings Explain to the student that a fixed pitch setting is dependent upon the amount of power applied at the time of the malfunction. If the failure occurs at a reduced power setting (low torque), the helicopter’s nose will turn when power is applied. When the failure occurs at an increased power setting (high torque), the nose of the helicopter will turn when power is reduced. Emphasize the use of the manufacturer’s recommended procedures for coping with either situation. Loss of Tail Rotor Components Make the student aware that if the loss of tail rotor components occurs, he or she will also experience a shift in the center of gravity. The student should understand that the severity of the situation is dependent upon the amount of weight lost. Impress upon the student that if a major failure allows something like the drive to begin whipping around, it could destroy the entire tail boom. Extended flight is not recommended after a failure of any kind. The helicopter can be repaired at a remote landing area much more quickly and at a much lower cost than rebuilding the helicopter after a crash landing 3 miles closer to the base of operations. If something on a helicopter fails, follow the RFM procedures. If there is any suspicion of a component failure, safely land as soon as possible. Unanticipated Yaw/Loss of Tail Rotor Effectiveness (LTE) Loss of tail rotor effectiveness (LTE), or unanticipated yaw, is not related to equipment malfunction, but rather is a result of the tail rotor not providing the adequate thrust required to maintain directional control. LTE may occur at airspeeds less than 30 knots and can be caused by a number of factors, including main rotor disk interference, weathercock stability, and tail rotor vortex ring state. It also depends upon wind direction and speed, altitude, and helicopter design. Thus, LTE offers a number of opportunities for the instructor to discuss the principles of aerodynamics and the physics involved in helicopter flight while reviewing a helicopter hazard. |
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