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. Show the student the major components of the fuel control system, if installed. Two types of fuel control system that are used today by most modern turbine helicopters are the FADEC and analog electronic engine control (EEC). True FADECs have no form of manual override available (in case of FADEC failure), giving the computer full authority over the operating parameters of the engine. If a total FADEC failure occurs, the engine fails. If the engine is controlled digitally and electronically but allows for manual override, it is considered an EEC or electronic control unit. An EEC allows the pilot to continue to operate the engine with the throttle while in emergency mode (manual mode). Electronic supervisory control allows the pilot to override the digital side of the fuel control and operate in the analog mode during emergency mode of operations. NOTE: Many turbines still utilize the older type electronic fuel control systems, which may not be quite as efficient as the newer systems, but operate without electrical power and are quite reliable. Manual operation is easily possible. Engines Reciprocating Engines Carburetor Explain to the student the need to make adjustments to the carburetor (“full rich” to “leaning the mixture”) and why. Refer the student to the FAA-approved Rotorcraft Flight Manual (RFM) and point out the specific procedures for a particular helicopter. Discuss with the student what the indications are if the fuel mixture is too rich (engine seems rough/reduced power) or leaned out too much (high engine temperature, possibly damaging). The mixture in most cases should be adjusted on the ground because an overly lean mixture can cause the engine to stop, resulting in a forced autorotation and attempt to restart the helicopter in flight. Carburetor Ice Figure depicts how ice affects the carburetor. Discuss with the student why ice may form on the internal surfaces of the carburetor. Carburetor ice has two sources: 1) Venturi cooling from air expansion and 2) fuel vaporization absorbing heat. Both effects combine to cool moisture in the air to below freezing. In some installations, the Venturi effect can cause icing around the butterfly in fuel injection systems, but it is a rare instance. Recommend reviewing FAA Advisory Circular (AC) 20-113, Pilot Precautions and Procedures To Be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems. Also, discuss the indications of carburetor icing (e.g., decrease in engine rpm or manifold pressure, carburetor air temperature gauge outside the safe operating range, and engine roughness) and how to correct for the icing condition. Point out to the student the FAA-approved RFM procedure for carburetor heat. Engine rpm should decrease as hot air is introduced into the engine because hot air is less dense. If the engine rpm does not decrease, the flight should be canceled until the defect is corrected and ensure that a deficiency entry is made into the helicopter’s logbook or maintenance tracking sheet. Explain to the student that Figure is a depiction of how a typical carburetor heat system functions. Remind the student at this time that if too little carburetor heat is applied and ice kills the engine, the freewheeling unit will prevent restarts of the engine without use of the starter. Fuel Injection Explain to the student how the fuel injection differs from the carburetor system and why the system eliminates carburetor icing. When there is no carburetor, airflow is controlled by butterfly but no need for venture because the fuel is injected under pressure which reduces the cooling effect. Also if the fuel is infected at the intake port of the engine, the fuel vaporization temperature drop doesn’t enter into the situation at all. Even if the fuel is injected at the butterfly, it vaporizes en route to the cylinder so the temperature drop occurs inside the warm engine where there is plenty of heat. Electrical Systems Show the student the electrical diagram that is provided by the helicopter manufacturer and discuss with the student the major components and functions of the electrical system. Explain how each system works with one another from the start sequence through the power off sequence (shutdown). At a minimum, show the student the location of the following items (if installed) and most importantly explain the function failure modes of the various components and enough about the locations for a thorough preflight: 1. Battery 2. Battery switch 3. Starting vibrator 4. Ammeter (discuss how to read it and what the numbers indicate) 5. Starter switch 6. Starter 7. Alternator 8. Alternator switch 9. All circuit breakers and switches (Note: FAA policy states that if a nonessential circuit breaker pops up or opens, do not reset in flight. If it is an essential circuit breaker, allow one reset only. Resetting circuit breakers could result in an in-flight fire. For more information, refer to the Special Airworthiness Information Bulletin, CE-10-11R1.) For a student flying a turbine-powered helicopter, point out the starter/generator. A starter/generator load indicator is often located on the pilot’s instrument panel to indicate the condition of the starter/generator system. A turbine helicopter pilot should fully understand the difference between a loadmeter and an ammeter and what the indications really mean in order to understand what the real failure is and the correct procedure to follow. Flight is still possible during a total loss of electrical power, and students should be taught to remain calm and safely land the helicopter. The engine continues to operate normally without electrical power. The battery, if fully charged, provides a limited time of power for items such as radio(s). Also, discuss the steps to take in the event of electrical circuit breakers tripping or fuses burning out. Electrical fire in flight should be covered as well. |
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