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. Most small helicopters have some type of seating limitations. Two examples are the Robinson R-22 and Robinson R-44. The R-22 has a 240-pound seat limit (includes any cargo below the seat). The R-44 has a 300-pound limit with a 50-pound cargo limit included within the 300 pounds. Therefore, if 50 pounds of cargo were placed under a seat, the passenger or pilot could weigh no more than 250 pounds. Also, the external load limit includes the weight of the load and the lifting slings and hardware. Determining Empty Weight A helicopter’s weight and balance records contain essential data, including a complete list of all installed optional equipment. Use these records to determine the weight and balance condition of the empty helicopter. Lead the student through a weight and balance problem, as well as preflight planning exercise before most flights. Once the student is proficient at weight and balance, then he or she should be allowed to reuse the previous planning information (provided that the conditions did not change). When a helicopter is delivered from the factory, the basic empty weight, empty weight CG, and useful load are recorded on a weight and balance data sheet included in the Federal Aviation Administration (FAA)-approved Rotorcraft Flight Manual (RFM). If equipment is removed, replaced, or additional equipment installed, these changes must be reflected in the weight and balance records. Major repairs or alterations must be recorded by a certificated mechanic. CG Forward of Forward Limit When the revised weight and moment are recorded on a new form, the old record is marked with the word “superseded” and dated with the effective date of the new record. Balance Some helicopters may be properly loaded for takeoff, but near the end of a long flight with almost empty fuel tanks, the CG may have shifted enough for the helicopter to be out of balance laterally or longitudinally. Before making any long flight, the CG with the fuel available for landing must be checked to ensure it is within the allowable range. It is essential to load the aircraft within the allowable CG range specified in the RFM’s weight and balance limitations. Center of Gravity (CG) The CG is defined as the theoretical point where all of the aircraft’s weight is considered to be concentrated. Improper balance of a helicopter’s load can result in serious control problems. The allowable range in which the CG may fall is called the CG range. The exact CG location and range are specified in the RFM for each helicopter. In addition to making a helicopter difficult to control, an out-of-balance loading condition also decreases maneuverability since cyclic control is less effective in the direction opposite to the CG location. Changing the CG changes the angle at which the aircraft hangs from the rotor. When the CG is directly under the rotor mast, the helicopter hangs horizontally; if the CG is too far forward of the mast, the helicopter hangs with its nose tilted down; if the CG is too far aft of the mast, the nose tilts up. [Figure 7-2] Discuss with the student some of the reactions of the helicopter and problems associated with a forward CG and an aft CG. Forward CG may occur when a heavy pilot and passenger take off without baggage or proper ballast located aft of the rotor mast. This situation becomes worse if the fuel tanks are located aft of the rotor mast because as fuel burns the CG continues to shift forward. Teach the student to assess the helicopter control response prior to each flight. Have the student get the helicopter light on the skids/gear and ensure helicopter is free of surface obstructions or attachments and will ascend to a hover in a nearly level attitude. Ensure that there is enough cyclic control to continue. Once at a low hover, ensure the helicopter remains nearly level. Point out to the student what a normal hover attitude looks like, and that if things do not feel or look right, then to lower the collective slowly and land the helicopter. Attempt to determine why the helicopter is responding in such a way. Adjustment or reduction of load may be necessary. Do not continue flight in this condition. Decelerating the helicopter in this condition may be very difficult or impossible as well. In the event of engine failure and the resulting autorotation, there may not be enough cyclic control to flare properly for the landing. CG Aft of Aft Limit Exceeding aft CG may occur when: . A lightweight pilot takes off solo with a full load of fuel located aft of the rotor mast. . A lightweight pilot takes off with maximum baggage allowed in a baggage compartment located aft of the rotor mast. . A lightweight pilot takes off with a combination of baggage and substantial fuel, both of which are aft of the rotor mast. Easily recognized when coming to a hover, the helicopter has a tail-low attitude, and needs excessive forward displacement of cyclic control to maintain a hover in a no-wind condition. If there is a wind, even greater forward cyclic is needed. NOTE: One technique used in smaller helicopters is to show the student what a tail-low (nose high) attitude looks like. To do this, seat the student (pilot seat) in a parked helicopter (engine off). Pull the tail boom down or lift the front skids until the tail stinger or guard touches ground. Tell the student to commit this helicopter position to memory and never allow the helicopter to achieve this attitude while in flight. Gusty or rough air could accelerate the helicopter to a speed faster than that produced with full forward cyclic control. In this case, dissymmetry of lift and blade flapping could cause the rotor disk to tilt aft. With full forward cyclic control already applied, a pilot might not be able to lower the rotor disk, resulting in possible loss of control or rotor blades striking the tail boom. Lateral Balance Discuss with the student the problems associated with lateral balances. |
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