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时间:2011-04-23 10:00来源:蓝天飞行翻译 作者:航空
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8.38A
700 TRANSIENT ROTOR DROOP CHARAC-TERISTICS
a. The T700 engine control system accurately maintains 100 % RPM R throughout the .ight envelope for most maneuvers. However, pilots should be aware that certain maneuvers performed with minimum collective applied will result in signi.cant transient rotor droop. High density al-titudes, heavy gross weights and operation at less than 100% RPM R will aggrevate this condition.
b.
During descent with little or no collective applied, Ng SPEED will be less than 80%. If % RPM R increases above 100%, the ECU torque motor input to the HMU is trimmed down in an attempt to restore 100% RPM 1/2 and % RPM R. When collective is increased, the LDS input demands more power, but the ECU continues to trim down until % RPM 1/2 returns to 100%. Since the Ng SPEED is at a slow speed, engine response time is greater. If rotor drag increases faster than the engine controller response, rotor droop occurs.

c.
During aggressive level deceleration (quick stop) or right turn approach maneuvers as the collective is raised and the nose lowered, % RPM R may droop to 95% or lower for1-2 seconds. % RPM R may then momentarily increase to 105-106% as the engine control system over-compensates for the reduced % RPM 1/2. Similar condi-tions of low collective, high % RPM R, and low Ng SPEED may be present during practice autorotations to a power recovery. After the .are as the nose is leveled and collective is increased, signi.cant transient droop can oc-cur. A rapid collective pull will aggravate the rotor droop.

d.
Maneuvers that rapidly load the rotor system with no collective input can result in transient droops as low as 92%. Transient droop is more pronounced at higher alti-tudes since the HMU reduces Ng SPEED acceleration as barometric pressure decreases.

e.
To minimize transient rotor droop, avoid situations which result in rapid rotor loading from low Ng SPEED and % TRQ conditions. Initiate maneuvers with collective inputs leading or simultaneous to cyclic inputs. During ap-proach and landing, maintain at least 15% -20% TRQ and transient droop will be minimal as hover power is applied.


Change 4 8-21

Section V ADVERSE ENVIRONMENTAL CONDITIONS
8.39 GENERAL.
This section informs the crewmembers of the special precautions and procedures to be followed during the vari-ous weather and climatic conditions that may be encoun-tered. This will be additional material to that already cov-ered in other chapters regarding the operation of the various helicopter systems. Refer to FM 1-202 for cold weather operations.
8.40 COLD WEATHER OPERATION.
The basic helicopter with normal servicing can operate at temperatures down to .34°C (.29°F).


Static electricity generated by the helicop-ter should be discharged before attempt-ing a sling or rescue hoist pickup. In cold, dry climatic conditions static electricity buildups are large. Use a conductor be-tween the helicopter and the ground to discharge the static charge. Delay lower-ing rescue hoist hook until helicopter is over the load, to lessen static charge buildup.
NOTE

During operation in cold weather, particu-larly when snow or moisture is present, the tail wheel locking indicating systems may give erroneous cockpit indications.
8.40.1 Cold Weather Pre.ight Check.


Ice removal shall never be done by scrap-ing or chipping. Remove ice by applying heat or deicing .uid.
Blade deice operation with erosion strips installed may cause blade damage.
a.
In addition to the checks in Section II check aircraft for ice or snow. If ice or snow is found, remove as much as possible by hand and thaw aircraft with heated air or deic-ing .uid before attempting start. Failure to remove ice and snow may cause damage.

b.
Check main rotor head and blades, tail rotor, .ight controls and engine inlets and hand holds for ice and snow. Failure to remove snow and ice accumulations can result in serious aerodynamic, structural effects in .ight and serious foreign object damage if ice is ingested into the engine. Check ENG POWER CONT levers for freedom of move-ment.
 
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