ENGINE AND INLET ANTI-ICE SYS Flashcards
(17 cards)
ENG Anti-Icing
What are the three ways to anti-ice the engine?
- Vent bleed air into the engine swirl vanes and inlet guide vanes by the engine anti-ice / start bleed valve
- Vent bleed air into the airframe engine inlet by the engine inlet anti-ice valve
- Continuously pump engine oil through the scroll vanes
2.1.9.2
ENG ANTI-ICE
ENG ANTI-ICE / INLET ANTI-ICE VALVE OPERATION
Solenoid-operated air valves
They are held closed electrically. De-energized the valves are opened. (Fail-safe ON)
BOTH controlled by ENG ANTI-ICE and DE-ICE MASTER switches on the upper console.
If DE-ICE MASTER is on ICE DETECTED opens the valve.
2.1.9.2
ENG ANTI-ICE SYS
Engine anti-ice / start bleed valve
Provides 5th stage bleed air to:
1. Engine swirl vanes
2. Inlet guide vanes
# Opens when:
- Engine anti-ice switches are selected ON
- Automatically during engine starts.
-Controlled by Variable Geometry Vane Servo
-Closes variably based on OAT and Ng. (Will be on below 80.5% Ng and will turn off between 80.5%-96.5% Ng) - DE-ICE MASTER switch ON and ICE DETECTED
2.1.10 & 2.1.10.1
ENG ANTI-ICE SYS
Indications of a malfunctioning Engine anti-ice/ start bleed valve
- Appearance or disappearance of the ENG ANTI-ICE ON advisory when outside of the range specified in the chart in Chapter 22.
- No illumination of [ENG ANTI-ICE ON] advisory when ENG ANTI-ICE switch is ON.
- No rise in TGT when ENG ANTI-ICE switch is selected ON.
With Engine Anti-ice ON maximum torque available is reduced up to 18% per engine.
2.1.20.1
ENG ANTI-ICE SYS
Inlet Anti-Ice Operation
Inlet anti-ice routes bleed air to the inlet cowling and inlet fairing.
Inlet anti-icing is a two part operation
(The solenoid and the bellows)
1. Inlet anti-ice solenoid valve
When the solenoid is energized the valve can not open. The solenoid must be de-energized for the bellows to allow bleed air into the inlet.
-Solenoid De-energized when:
1. ENG ENTI-ICE switches ON
2. DE-ICE MASTER switch ON and ICE DETECTED
2. Freon-filled Bellows
Freon expands and contracts based on OAT and thus opens or closes the valve based on OAT.
- OAT less than 4C, valve open
- OAT between 4-13C, valve is variably opened OAT dependent
- OAT greater than 13C, valve closed
A temperature switch activates the [INLET ANTI-ICE ON] advisory when inlet temperature exceeds 93C. This indicates whether or not bleed air is actually reaching the inlet.
2.1.10.2
ENG ANTI-ICE SYS
Indications of a malfunctioning Inlet Anti-Ice Valve
[INLET ANTI-ICE ON] advisory when OAT > 13C
The resultant loss of torque could be a maximum of 49% when the anti-ice valves are open.
2.1.10.2
ENG ANTI-ICE SYS
Where is the engine anti-ice start/bleed valve located?
mounted to the bottom of the compressor section
2.1.10
DE-ICE/ANTI-ICE SYS
The DE-ICE MASTER switch position controls what function?
ON = ENG ANTI-ICE, WINDSHIELD ANTI-ICE, and BLADE DE-ICE POWER systems automatically function when ice accumulation sensed by ice detector
OFF = automatic function disabled
ENG ANTI-ICE, WINDSHIELD ANTI-ICE, and/or BLADE DE-ICE POWER ON= disables automatic functionality, appropriate system will operate continuously
2.17.1
How does the ice detector sense ice accumulation? How can you determine the severity of icing?
Ice detector, mounted on No.2 engine cowling, senses ice accumulation on a vibrating probe by measuring the change in probe frequency.
Simultaneously, an aspirator heater on the probe is turned on to heat the probe, and shed the accumulated ice, resetting it for another cycle.
Severity of icing environment is proportional to the rate at which the probe heater is cycled.
2.17.3.2
DE-ICE/ANTI-ICE SYS
Blade De-ice Systems
Main, tail, droop stop
Main Rotor:
Controller sends command signal through slip ring to distributor which sequences main rotor blade heater zones.
This reduces power requirements during MR de-icing.
Tail Rotor:
No distributor, elements heated simultaneously.
Droop Stop Heaters
Continuousely heated with BLADE DEICE control panel power in ON or TEST
AUTO Mode:
Rate signal is sent to the controller which sends off times proportional to ice rate.
MANUAL Mode:
Trace, Light, Moderate fixed signals are transmitted to the controller. Should be used with an indication of icing rate system malfunction [ICE DETECT FAIL] caution.
2.17.3.2
DE-ICE/ANTI-ICE SYS
When should the Blade De-Ice MANUAL (T, L, M) mode be used?
When [ICE DETECT FAIL] illuminates or when there is no indication of failure but one of the three following conditions exist:
- The pilot has determined by judgement of icing intensity that the ice rate system is inaccurate
- Torque required has increased to an unacceptable level
- helicopter vibration has increased to an unacceptable level
2.17.3.2
DE-ICE/ANTI-ICE SYS
Windshield anti-ice
Pilot and copilot windshields seperate electrically heated safety glass with heating elements and temperature sensors.
Operates with:
COPILOT or PILOT WINDSHIELD ANTI-ICE switch ON
DE-ICE MASTER switch ON with ICE DETECTED
When is pitot heat required?
Pitot heat shall be turned on when OAT is 5C and below or when visible moisture is present.
WARNING: Failure to turn on pitot heat in icing conditions may cause erroneous airspeed indications, which can lead to erratic and/or downward programming of the stabilator and loss of control of the aircraft.
2.17.5
When are anti-ice/de-ice systems required?
shall be turned on prior to entering visible moisture (including clouds) at ambient temperatures of 5C or less.
An additional torque increase up to ______% per engine may be experienced due to ice buildup during normal operation of the blade de-ice system.
14%
Ice accumulation resulting in a ______% torque increase indicates that normal autorotational rotor rpm may not be attainable should a dual engine failure occur.
20%
What is the difference between main and tail rotor de-icing?
Main rotor blades are de-iced in cycles and the tail rotor blades are de-iced simultaneously
Main rotor blades are de-iced in cycles to reduce power requirements, to de-ice in cycles the main rotor blades have a blade de-ice distributor
