直升机飞行手册 Helicopter Flying Handbook

时间：2014-11-09 12:30来源：FAA 作者：直升机翻译 点击：次

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After the descent and airspeed are established, roll into the turn. The turn should be approximately 180°, winds may cause the actual turn to be more or less than 180°. For training purposes, initially roll into a bank of a least 30°, but no more than 50°– 60°. Continuously check airspeed, rotor rpm, and trim throughout the turn. It is important to maintain the proper airspeed and to keep the aircraft in trim. Changes in the aircraft’s attitude and the angle of bank cause a corresponding change in rotor rpm. Adjust the collective, as necessary, in the turn to maintain rotor rpm in the green arc.
At the 90° point, check the progress of the turn by glancing toward the landing area. Plan the second 90 degrees of turn to roll out on the centerline. If the helicopter is too close, decrease the bank angle; if too far out, increase the bank angle. Adjusting the bank angle will change the G loading, which in turn alters the airflow and results in rotor rpm changes. Keep the helicopter in trim with antitorque pedals.
The turn should be completed and the helicopter aligned with the intended touchdown area prior to passing through 100 feet AGL. If the collective pitch was temporarily increased to control the rpm, it may need to be lowered on rollout to prevent decay in rpm. Make an immediate power recovery if the aircraft is not aligned with the touchdown point, and if the rotor rpm and/or airspeed are not within proper limits. Otherwise, complete the procedure as if it were a straight-in autorotation.
Common Errors
1. Failure to maintain trim during the turn (increases rate of descent).
2. Failure to maintain autorotation airspeed.
3. Failure to hold proper pitch attitude for type helicopter (too high or too low).
4. Failure to have proper alignment with touchdown zone by 100 feet AGL.
5. Failure to maintain rotor rpm within limits during the maneuver.
6. Failure to go around if not within limits and specified criteria for safe autorotation.
Practice Autorotation With a Power Recovery
A power recovery is used to terminate practice autorotations at a point prior to actual touchdown. After the power recovery, a landing can be made or a go-around initiated.
Technique
At approximately 3–15 feet landing gear height AGL, depending upon the helicopter being used, begin to level the helicopter with forward cyclic control. Avoid excessive nose-high, tail-low attitude below 10 feet. Just prior to achieving level attitude, with the nose still slightly up, coordinate upward collective pitch control with an increase in the throttle to join the needles at operating rpm. The throttle and collective pitch must be coordinated properly.
If the throttle is increased too fast or too much, an engine overspeed can occur; if throttle is increased too slowly or too little in proportion to the increase in collective pitch, a loss of rotor rpm results. Use sufficient collective pitch to stop the descent, but keep in mind that the collective pitch application must be gradual to allow for engine response. Coordinate proper antitorque pedal pressure to maintain heading. When a landing is to be made following the power recovery, bring the helicopter to a hover at hovering altitude and then descend to a landing.
When practicing autorotations with power recovery in nearly all helicopters, the throttle or power levers should be at the flight setting at the beginning of the flare. As the rotor system begins to dissipate its energy, the engine is up to speed as the needles join when the rotor decreases into the normal flight rpm.
Helicopters that do not have the throttle control located on the collective require some additional prudence. The autorotation should be initiated with the power levers left in the “flight,” or normal, position. If a full touchdown is to be practiced, it is common technique to move the power levers to the idle position once the landing area can safely be reached. In most helicopters, the pilot is fully committed at that point to make a power-off landing. However, it may be possible to make a power recovery prior to passing through 100 feet AGL if the powerplant can recover within that time period and the instructor is very proficient. The pilot should comply with the RFM instructions in all cases.

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