ICE AND RAIN PROTECTION AIRFRAME DE-ICING Description Controls and indicators of the AIRFRAME DE-ICING system are located at the ice protection panel. Airframe de-icing is accomplished by alternately inflating and deflating rubber boots installed on the leading edges of the wings and tail section. The boots are inflated and deflated in sequence, symmetrically, across the airframe. Engine bleed-air is supplied to the boots via pressure-regulating valves and distribution valves. Each distribution valve has two outlets. If bleed-air pressure is insufficient either in the supply line to the distribution valves or at the outlets of the tail distribution valves, a lowpressure alert will be presented. One engine can supply sufficient bleed-air for the de-icing system. The distribution valves are controlled by a cyclic timer. A de-icing cycle lasts about one minute. Selection can be made for continuous (HEAVY) or periodic (LIGHT) operation. In case of a timer fault, the distribution valves can be controlled by the MANUAL de-icing selector. The tail plane distribution valves are electrically heated. Page 1
Functional diagram Page 2
Controls and indicators Page 3
Alerts CONDITION(S) / LEVEL AURAL MWL/MCL CAP LOCAL TIMER FAILURE 2 CAUTION TIMER FAULT TIMER FAILURE 2 CAUTION LOW PRESS Page 4
ENGINE ANTI-ICING Description The formation of ice on propeller and spinner is prevented by electrical heating, and in the air intake by electrical and bleed-air heating. In addition heated engine oil is used to prevent the formation of ice on the inlet case of the LP compressor. Controls and indicators of the electrical engine anti-icing system are located at the ice protection panel and at the glare shield. The system is armed to operate when the ENGINE ANTI-ICING pushbutton at the ice protection panel is depressed to ON. When either ENGINE ANTI-ICING pushbutton is depressed to ON, two ENG A-I lights, located at the glare shield, illuminate. The system is activated when the Total Air Temperature (TAT) falls below 5ºC, provided the propeller speed is above 50%. The system is automatically de-activated when TAT rises above 7ºC or the propeller speed drops below 50%. Several surfaces in the air intake are heated electrically and separately. The leading edge of the air intake and part of the intake duct are heated continuously, while all other surfaces, including propeller and spinner, are heated periodically. Periodic activity is controlled by a cycle timer and varies automatically with ambient temperature. If a fault in the heating of any surface is detected, an engine anti-icing alert will be presented and the electrical power to that particular surface is switched off automatically. If the timer fails, also indicated by the engine anti-icing alert, all electrical heating is disabled. Part of the air intake is heated with bleed-air, tapped upstream of the PR/SO valve in the engine bleed-air system. Bleed-air is admitted via a shut-off valve. The valve opens when the ENGINE ANTI-ICING pushbutton is depressed to ON, irrespective of the TAT. If the system is switched ON and no pressure is available, the engine anti-icing alert is presented. Page 5
Controls and indicators Page 6
Alerts CONDITION(S) / LEVEL AURAL MWL/MCL CAP LOCAL L ENG A-ICE ENGINE ANTI-ICING ENGINE ANT-ICING SYSTEM FAILURE 2 CAUTION OR FAULT ON R ENG A-ICE Page 7
WINDOW HEAT Description The flight deck front windows are heated electrically to prevent ice build-up, to increase bird impact resistance, and to prevent misting. Controls and indicators are located at the ice protection panel. Each front window has a heating control unit. A temperature sensor in each window signals the actual temperature to the related control unit which accordingly activates or de-activates the heating, provided the window heat is selected on. The side windows are not heated. Demisting of flight deck windows can be performed with airflow from the airconditioning system. See AIRCONDITIONING/PRESSURIZATION. Window heat type I Each front window has a heating control unit. A temperature sensor in each window signals the actual temperature to the related control unit which accordingly activates or de-activates the heating, provided the window heat is selected on. The window heat selector has three selector positions, OFF, LO and HI. Heat build-up is slow in the LO mode and fast in the HI mode. Mode selection does not affect the temperatures at which the window heat is activated and de-activated. If a failure is detected, an alert will be presented. Fault detection is active when an other mode is selected, and when electrical power is applied to the system provided the system is not selected OFF. The left and right window can be switched OFF individually by depressing the respective pushbutton located at the ice protection panel. Window heat type II Each front window has a heating control unit. A temperature sensor in each window signals the actual temperature to the related control unit which accordingly activates or de-activates the heating, provided the window heat is selected on. The left and right window can be switched OFF individually by depressing the respective pushbutton located at the ice protection panel. If a failure is detected power to the heating element will be interrupted and an alert will be presented. Page 8
Controls and indicators Controls and indicators - Type I Page 9
Controls and indicators - Type II Page 10
Alerts CONDITION(S) / LEVEL AURAL MWL/MCL CAP LOCAL WINDOW HEAT FAILURE 1 FAULT Page 11
PROBE AND VANE HEAT Probe heat To prevent the formation of ice on air data sensors, electrical heating is provided for pitotstatic heads and angle-of-attack vane. Controls and indicators of the probe heat system are located at the ice protection panel. The pitot heads are heated when the relevant pushbutton is blank and electrical power is available. In battery-power-only condition, only the left-hand lower head (L LO), which supplies information for the captain s air data instruments, remains heated. In the event that a pilot heat system fails or a pitot heat system is OFF when the parking brake is released, an alert will be presented. Vane heat Type I The angle-of-attack vane heater is active when the VANE pushbutton is blank and the aircraft is airborne. Type II The angle-of-attack vane heater is active when the VANE pushbutton is blank. All In the event that the heater fails an alert will be presented. Page 12
Controls and indicators Controls and indicators - Type I Page 13
Controls and indicators - Type II Page 14
Alerts CONDITION(S) / LEVEL AURAL MWL/MCL CAP LOCAL PITOT HEAT OFF AFTER PARKING BRAKE RELEASE 1 INOP OFF PITOTS PITOT HEAT FAILURE 2 CAUTION PITOT HEAT INOP VANE VANE HEAT FAILURE 2 INOP CAUTION Page 15
RAIN PROTECTION Description Type I Rain is removed from the flight deck front windows by two wipers. The wipers are driven by a single four-speed electric motor, which is operated by the wiper speed selector at the overhead panel. Wiper operation stops in the park position when the selector is turned via OFF to PARK. The selector is spring loaded from PARK to OFF. Type II Rain is removed from the flight deck front windows by two wipers. The wipers each driven by a two-speed electric motor are controlled by the window wiper speed selector at the overhead panel. The selector has a low and a high position for operating the wipers. The wipers will return to the park position when the selector is positioned to OFF. Type III Rain is removed from the flight deck front windows by two wipers. Each wiper is driven by an independent two-speed electric motor, and can be controlled by the window wiper speed selectors at the side panels. Each selector has a low and a high position for operating the respective wiper, and a both high position for operating both wipers. The respective wiper will return to the park position when the selector is positioned to OFF and the offside selector is not in the both high position. Page 16
Controls and indicators I Controls and indicators - Type I Page 17
Controls and indicators - Type II Page 18
Controls and indicators - Type III Page 19
SYSTEM OPERATION Engine anti-icing Engine anti-icing must be switched ON when icing conditions are encountered or anticipated. Switch anti-icing off three minutes after icing has ceased and in clear air. Icing can be expected to occur when the ambient temperature or TAT is below plus 5 deg C, when visible moisture is present or when standing water or slush is present on the ground. CAUTION: Use the criteria of TAT and visible moisture for switching on the engine Antiicing system. Insufficient ice shedding from the non-heated parts of the propeller is noticed as propeller vibration. If ice on propeller is noticed as propeller causes excessive vibration: ERP...SELECT MCT TORQUE... ADJUST Set torque according to tables ERP INOPERATIVE Airframe de-icing On ground procedure If the airplane was parked overnight in sub-zero temperatures, it is recommended to check airframe de-icing operation before the first flight of the day. After engine start operate the system in MANUAL 1 and 2 twice and visually check the wing leading edge boots outside the engine nacelle for inflation. In-flight procedure When ice deposits are detected, the airframe de-icing system must be switched to LIGHT. When the thickness of the ice deposit layer building up between cycles, is estimated to be more than ¼ inch (6 mm) or when the crew judges that conditions so justify, select HEAVY. The airframe de-icing system must be kept in operation as long as ice accumulation continues. When the ice has been removed the system must be switched OFF. Some residual ice is normal, especially with low TAT s. Before commencing the approach at a TAT below plus 10 deg C, select the airframe de-icing system to HEAVY for approx 3 minutes to clear the airframe of any residual ice unless it is confirmed that the wing boots are clean. Page 20
Window heat The window heat must be switched on when TAT is below plus 18 degrees C. For type I window heat Operate the heating at least 3 minutes in LO before using HI. Probe heat All probe heaters should be switched ON whenever the aircraft is moved by its own power. Wiper Use wipers with precipitation only. Operation with engine anti-icing inoperative Operate the aircraft such that no icing conditions will be encountered. Operation in icing conditions with engine anti-icing OFF CAUTION: In case of too late a detection of icing conditions, operate engine anti-icing on one engine at a time with an interval of two minutes. Page 21