De-Ice Flashcards
DE-ICE MASTER on automatically
Turns on
ENG ANTI-ICE, WINDSHIELD ANTI-ICE, and BLADE DE-ICE POWER (even if their physical respective switch is off)
when ice accumulation is sensed by the ice detector
ICE DETECTED
Caution illuminates when ice detector senses ice
DE-ICE MASTER - off
Disables automatic function
DE-ICE MASTER on with
ENG ANTI-ICE, WINDSHIELD ANTI-ICE, or BLADE DEICE POWER switches in the on position will also disable automatic function (as appropriate system will operate continuously…because it is on)
The rotor blade deice system consists of:
- System control panel
- Test panel
- System controller
- Power distributor
- Main and tail slip rings
- Main and tail blade heating elements
- Caution lights
- OAT sensor
- Modified ambient sense line
- Ice detectoe/signal converter subsystem
The blade deice system provides
Controlled electrical power to integral heating elements in the main and tail rotor blades, causing the ice bond layer to weaken, allowing symmetrical ice shedding
Can the system be ground-checked?
Yes, the blade deice system may be ground-checkednwith the use of external power. Ac power is supplied through thr blade deice distributor.
The EOT (Element-on-time) feature can NOT be checked on the ground.
BLADE DEICE control panel warning
Leaving the BLADE DEICE POWER switch in the test position can lead to blade damage
The ice detector is
Mounted on the No. 2 engine cowling, senses ice accumulation on a vibrating probe by measuring the change in probe frequency.
When the ice detector senses ice accumulation, the ICE DETECTED caution will be illuminated. Simultaneously, an aspirator heater on the probe is turned on to heat the probe, shed the accumulated ice, and reset it for another cycle.
Severity of the icing is
Proportional to the rate at which the probe heater is cycled
What governs the EOT heating?
OAT sensor below the windshield
Lower OAT = longer EOT
With mode selected AUTO, the controller processes the ice-rate signal to produce heating element off-time and the OAT signal yo produce the heater EOT.
Controller sends command signals through
The main rotor slipping to the blade deice distributor
How are the blades deiced?
In cycles to reduce power requirements
What does the system distributor do?
Switches power in sequence to the main rotor blade heater zones
Why isn’t there a tail rotor blade distributor?
Because power is applied to the four tail blades simultaneously
What do droop-stop heaters do?
Supply heat to the droop-stop pins and cams during icing conditions
The droop stops are continuously heated as long as the BLADE DEICE power is in ON or TEST
As a pilot you can control what via the rotary switch?
Fixed off time of the blade heaters.
Via in MANUAL mode: T, L, and M
Selected one of these maula modes if there is a ICE DETECT FAIL caution
When should you use MANUAL mode (apart from ICE DETECT FAIL):
- Pilot has determined by judgement of icing intensity that the ice rate system is inaccurate
- Torque required has increased to an unacceptable level
- Helicopter vibratiojnhas increased to an unacceptable level
BLADE DE-ICE TEST
BIT
Tests caution lights and circuitry
Two amber PWR lights on panel warn of power malfs of main or t/r deice system
What does the BLADE DEICE TEST do?
Allows deice system to test for failures that are otherwise doemand during normal test mode
through introducing selected failure signals into the system and then requiring BIT circuitry to function in a specific manner
Windshield Anti-Ice system is used to
Prevent ice and fog from forming on windshields
What is the windshield anti-ice slcomprised of
Pilot and co-pilot windshields are electrically heated safety glass with heating elements and built-in temperature sensors
Both windshields have their own separate anti-ice system
Pilot or co-pilot WINDSHIELD ANTI-ICE - on does what?
Sends power to the windshield heating elements
Windshield anti-ice system warning:
A faulty windshields anti-ice system could result in arcing and delamination of the windshield
If not secured in a timely manner, an electrical fire could result
Pitot-static tube heaters are located
In the pitot tube and static ports to keep ice from forming on the tube and ports and help keep moisture out
Pitot heaters are controlled by
PITOT HEAT switch
RIGHT PITOT HEAT
LEFT PITOT HEAT
cautions indicate a low or not-heat condition when the switch is ON
Pitot heat warning
Shall be turned on when visible moisture is present and/or the OAT is 5°C or below
Failure to turn on pitot heat on icing conditions may cause erroneous airspeed indications, which can lead to erratic and/or downward programming of thr stabilator and loss of control of the aircraft
NOTE: don’t use to warm flight equipment
BLADE DEICE TEST panel:
- Norm
- Sync 1
- Sync 2
- OAT
- EOT
- Norm = provides signal path for normal ops
- Sync 1 = signal path to the controller
- Sync 2 = open circuit to the controller
- OAT = short circuits OAT to check BIT, sense fault when power - test
- EOT = disables OAT sensor BIT circuits to simulate defect in EOT timing circuit (on + mode m)
System controller power route
- Main rotor
- T/r
- Sends comand signals ➡️ m/r sliprings ➡️ distributor ➡️ m/r heater zones (heated in cycles to reduce power reqs)
- Skips distributor and sends command signals ➡️ t/r sliprings ➡️ t/r blades (all 4 t/r blades heated simulatenously)
