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CE750 Pneumatics
Pneumatics
Question | Answer |
---|---|
What is HP air normally used for? | 1. pressurization 2. air conditioning 3. anti-icing 4. engine starting 5. service air |
What is LP air normally used for? | 1. pressurization 2. air conditioning 3. limited anti-icing (during Takeoff phase only) |
What is APU bleed air used for? | 1. Air conditioning 2. Engine start 3. Service air 4. Pressurization |
What is the highest altitude for use of APU bleed air? | FL310 |
Can the APU bleed air operate the anti-icing systems? | No |
Where is the Ground Air Cart (Huffer) receptacle? | Right aft fuselage |
What do the HP/LP crossover valves do? | Allows HP air into the LP line, or if the HP firewall valve is closed, allows LP bleed air into the anti-icing lines |
What does the isolation valve do? | Normally keeps each PAC separately supplied with air from its own engine, but can be opened to allow one engine to supply bleed air to both PACs |
What position should the isolation valve be in to do a crossbleed start of the right engine using the bleed air from the left engine? | Open |
If there is a loss of DC electric power, what does the LP bleed air valve do? | GOes to the open position allowing bleed air to flow so that pressurization will continue to be provided |
Where is service air extracted from the HP bleed air line? | Before the firewall shutoff valve (service air cannot be shut off) |
What switch operates the LP and HP bleed air firewall shutoff valves? | L ENG BLD AIR and R ENG BLD AIR switches on the co-pilot's panel |
How is HP bleed air cooled? | After passing the HP firewall shutoff valve, HP bleed air goes through a Pre Cooler on the engine pylon. The pre cooler has ram air intake on top of the pylon and exhaust on the bottom of the pylon. |
How are the HP Pre Cooler doors operated? | automatically by an electric motor, depending on the temperature of the heat exchanger downstream from the Pre Cooler |
How is a bleed air leak detected in the pylon? | Temperature sensors in the pulon will detect abnormal temps and illuminate the red PYLON BLD LEAK L or R message in the CAS |
What controls the HP/LP crossover valve? | A single switch labeled PAC BLEED SELECT on the co-pilot's panel |
If there is a loss of DC power, what position does the HP/LP crossover valve go to? | They close, keeping HP and LP air separate |
Are there cases when the HP/LP crossover valve will be automatically opened and closed? | Yes, in response to aircraft configuration |
How do we know the position of the HP/LP crossover valve? | A white CAS message PAC HP VALVE OPN L or R will indicate that HP air is now available to that PAC |
Can HP air be used for PAC operation at the same time that it is being used for anti ice purposes? | No |
What is the normal position that should be selected (unless otherwise directed by a checklist) for the PAC BLEED SELECT switch? | Norm, to allow automatic functioning |
What is the purpose of the MAX COOL switch on the APU panel? | Increased flow of bleed air directly to PACs for a high level of cooling capabilities |
Should MAX COOL be used during engine start? | No, and it will automatically be closed if the pilot forgets to turn it to Bleed On position during start |
What is the purpose of the PAC isolation valve? | To allow one source of bleed air to power both PACs, and to allow left engine bleed air to enter the start duct of the right engine for cross bleed starts without APU or Ground Service Air. |
What is the normal position of the PAC isolation valve? | Closed |
With the loss of DC electric power, what position does the PAC isolation valve go to? | Closed |
Is there an EICAS message that annunciates or monitors the position of the PAC isolation valve? | No |
When are the HP firewall shutoff valves automatically closed, if the L and R ENG BLD knobs remain in the HP/LP position? | 1. During Takeoff with an anti-ice switch in the on position 2. When an HP duct over-pressure condition exists |
What do the HP/LP crossover valves do during the takeoff roll with an anti-ice switch in the on position? | They allow LP air to enter the HP bleed lines for short term anti icing capabilities, so that HP air can be dedicated exclusively to power production until the WOW switch indicates that the aircraft is airborne |
Why do the HP firewall shutoff valves close during a takeoff roll with an anti ice switch in the on position? | To prevent over-heating in the pylon due to insufficient airflow through the precooler at slow speeds |
Will the EICAS display a reoccuring message of HP DUCT O'PRESS if no action is initially taken? | Yes, as the HP firewall shutoff valve turns on and off automatically, the EICAS message will also cycle on and off |
IF PAC BLD Select switch is in Norm, aircraft is on the ground at idle power, and no anti ice switches are selected, what are the position of the pneumatic valves? | Crossover valve is open, allowing HP air to reach the PACs. When TLA exceeds 32 degrees, the crossover closes. |
Is the RAT probe aspirated by service air when the aircraft is airborne? | No, only on the ground |
Can live animals be carried in the baggage compartment? | No |
Is the baggage compartment pressurized? Heated | Yes and Yes |
Does the baggage compartment have an inflatable seal like the main cabin door? | Yes |
If the baggage compartment loses pressurization can it be isolated from the main cabin? | Yes |
What items use service air? | Main cabin door seal Main cabin door acoustic seal Baggage compartment door seal Vacuum ejector Baggage compartment heat RAT aspiration |
Which PAC is primarily supplied by the right engine? | Cabin |
Which PAC is primarily supplied by the left engine? | Cockpit |
What are the protection systems for the HP bleed line? | Over temp and Over pressure sensors |
Can any switch be in High for takeoff with anti-ice on? | No |
What is the max altitude for the PAC BLEED SELECT switch to be in Low? | FL 410 |
When is operation a CKPT PAC or CBN PAC switch not allowed to be in the High position? | Takeoff, Landing, or above FL 450 |
What is the maximum altitude for operating with a single PAC inoperative? | FL 410 |
If only one engine is supplying bleed air to the PACs, and one of the PAC selectors is in the HIGH position, what is the maximum operating altitude for the aircraft? | FL 250 |
Can a ground service air cart provide air to the PACs? | Yes. The isolation valve will have to be opened to supply the cockpit PAC. |