The engine can incur FOD by improper use of these systems and the other anti-ice/deice systems. For example, ice shed-ding off the windshield can cause FOD damage to the engines.
a.
The engine is anti-iced by two systems; the .rst de-scribed in subparagraph b is called an engine anti-ice sys-tem and a second described in paragraph 2.22.2 is called the engine inlet anti-icing. Both of these systems are turned on by the ENG ANTI-ICE NO. 1 and NO. 2 switch (Fig-ure 2-6).
b.
Engine anti-icing is a combination of bleed-air and heated engine oil. Anti-icing is controlled by a solenoid-operated air valve. The engine anti-ice/start bleed valve opens during starting and will remain open at low power settings until engine reaches 88 to 92% Ng, depending on the outside air temperature, with anti-ice OFF. The engine anti-ice/deice system is designed so that in the event of an electrical failure the valve reverts to the anti-icing mode and turns on an advisory legend indicating #1 ENG ANTI-ICE ON or #2 ENG ANTI-ICE ON. Axial compressor discharge air is bled from stage .ve of the compressor cas-ing, routed through the anti-icing/bleed valve, and deliv-ered to the front frame through ducting. Within the swirl frame, hot air is ducted around the outer casing to each swirl vane splitter lip and inlet guide vanes. The hot air is directed within each vane by a series of baffles. Hot engine oil passing within the scroll vanes in the main frame pre-vents ice buildup. Water, snow, and solids are carried out through the inlet particle separator discharge system. Switches marked ENG ANTI-ICE NO. 1 or NO. 2 OFF, and ON, control engine and inlet anti-ice. At the ON posi-tion, compressor bleed-air is supplied continuously. Power to operate the anti-icing system is by the No. 1 and No. 2 dc primary buses respectively, through circuit breakers, marked NO. 1 ENG ANTI-ICE and ANTI-ICE WARN, NO. 2 ENG ANTI-ICE and ANTI-ICE WARN respec-tively.
2-22 Change 4 2.22.2 Engine Inlet Anti-Icing.
a. The engine air inlets are anti-iced by bleed-air from the engines. Four advisory legends, marked #1 ENG ANTI-ICE ON, #2 ENG ANTI-ICE ON, #1 INL ANTI-ICE ON and #2 INL ANTI-ICE ON are provided for the engines. The #1 and #2 ENG ANTI-ICE ON advisory legends will go on when the ENG ANTI-ICE NO. 1 and ENG ANTI-ICE NO. 2 switches are placed ON. When the anti-ice system is operating and an engine is started, the inlet anti-ice valve for that engine will close. The #1 and #2 INL ANTI-ICE ON advisory legends operate from tem-perature sensed at the engine inlet fairing. When the tem-perature reaches about 93°C (199°F), the temperature switch will turn on the appropriate INL ANTI-ICE ON advisory legend. If this legend goes on with the switches at ENG ANTI-ICE NO. 1 and NO. 2 OFF, it indicates that heat is being applied to that engine inlet and a malfunction exists. Inlet anti-icing will turn on if dc primary power failure occurs; dc electrical power is applied to keep the valve closed. Functioning of ENG INLET ANTI-ICE is controlled as follows:
(1)
Above 13°C (55°F) -Illumination of the INL ANTI-ICE ON advisory legend indicates a system mal-function.
(2)
Above 4°C (39°F) to 13°C (55°F) -The INL ANTI-ICE ON advisory legend may illuminate or may not illuminate.
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