How to Master B787 Air System
Air System – CAC’s Supply Pressurized HOT AIR To The Packs
Two CAC’s Dedicated To Each Pack.All CACs Are Commanded OFF During Engine Start And will Start Operating Two Minutes After The Second Engine Start. In Case Of In-Flight Starter Assisted Engine Start, Only One CAC Runs To Maintain Pack Operation
Deflector doors
Deploy In front of the CAC’s On Ground & During Landing To Protect It From Debris. Doors May Retract In Temps of 2° C and 35° C
Packs Supply Cool Air
Two Identical Systems (A Dual channel), If One Fails The Pack Control Automatically Switches To The Other System. Standby Cooling Mode. In Certain Malfunctions Pack Control Automatically Uses Standby Cooling Mode As A Backup To The Normal Mode With An EICAS Advisory PACK MODE (L, R) And STBY COOLING.
Pack Ground Operation
When APU Sufficient Main AC BUS Power Available (Normally One CAC In Each Pack Runs When APU Is Running)- – (THE USE OF EXTERNAL AC POWER FOR THE AIRCONDITION IS NOT RECOMMENDED)During Cold Weather Operations Both CACs Are Commanded ON
Trim AirTwo Separate Systems, Left And Right
Trim Air Mixes The Hot CAC Air With The Cooled Pack Air.
Alternate ventilating system (AVS)
Operates At 13000 Feet.
The AVS Provides An Alternate Means Of Ventilating For The Cabin And The Flight Deck In The Event of Both Packs Are Inoperative. The System Uses Both FWD And AFT Outflow Valves To Control Airflow Into The Aircraft. When The Alternate Ventilation Switch Is Selected To ALTN the FWD Out Flow Valve Positions To The 10 o’clock Position And The AFT To The 1 o’clock Position.
Recirculation System
Upper Recirculation System
Draws Air From The Upper Portion Of The Cabin, Filters The Air And Then Reintroduces It Back Into The Cabin Through The Conditioned Air Distribution System
Lower Recirculation System
Air is Exhausted Overboard Through The Outflow Valves Or Picked Up By The Lower Recirculation System, Filtered And Cooled By The Integrated Cooling System Then Mixed With The Pack Air And Then Reintroduced Into The Cabin.
Humidity systems
De-Humidification System
Operates Automatically And Uses Two Zonal Dryers (FWD & AFT) To Remove Moist Air
Humidification System
Dry air is Recirculated Back, And Moist Air Is Exhausted Below The Cabin Floor
Equipment Cooling
FWD Equipment Cooling
Supplies Cooling And Smoke Removal For The FWD Centre And Flight Deck
-Consists Of Two Supply Fans (Primary And Backup), If The Primary Fan Fails The backup Automatically Operates.-A Ventilation Fan Forces The Warm Air Overboard
-Provides Cooling And Ventilation For The FWD E/E Compartment And Flight Deck Electronics.
-Exhaust Air Is Ducted Into The Forward Cargo Compartment.
AFT Equipment Cooling
-Consists Of Two Supply Fans (Primary And Backup), If The Primary Fan Fails The Backup Automatically Operates.-An Exhaust Fan Forces Warm Air Overboard.
-Provides Cooling And Ventilation For The AFT E/E.-Exhaust Air Is Ducted Into The AFT And Bulk Cargo Compartments.
Miscellaneous Cooling
Provides Cooling For Non-Essential Equipment in the Crown and Lower deck. It Also Provides Cooling To The (IFE) Flight Entertainment System. Operation Is Fully Automatic
Lavatory/Galley Ventilation System
Provides Ventilation To The lavatories And the Galley, It Also Provides Smoke Control For The Lavatories And The Crew Rest Compartment. Operation Is Fully Automatic. It Also Provides A Second Set Of Heat Exchangers To Help Cool The PECS
Power Electronics Cooling System (PECS)
- Fully Automatic And No Flight Crew Action Required In Normal And Non-Normal Operation.
- Its The Primary Cooling System For The Large Motor Power Distribution System In The E/E Compartment. It Also Cools The Other Liquid Cooling Systems And The ICS.
- Its Orange In Color To Be Easily Identified In Case Of A Leak
- It Consists Of Two Independed Left & Right Cooling Loops.-Each Loop Has Its Own Pump That Consists Of A Primary And Secondary Pump And A Fluid Reservoir. Cooling For Each Loop Is From A Primary And Secondary Heat Exchanger.
Integrated Cooling System
- No Flight Deck Controls OR Indications
- Its Orange In Color To Be Easily Identified In Case Of A Leak
The ICS Is Cooled By Four Detected Vapor-Cycle Reirrigation Packages Called Secondary Cooling Units And They Are Cooled By Two In The Left PECS Loop And Two In The Right.Centralized Refrigeration System, Provides Cooling To The Galley Carts, And Assists With Cooling Recirculated Cabin Air Integrated With The Air Conditioning System, And The Liquid Cooling System
FWD Cargo Compartment
- Automatic Overheat Protection
- A Target Temp Of 21° C Is Commanded
if An Automatic Shutdown Occurs The Cargo Heat Can Not Be Restored In flight.
The AMBER OFF light Means (System On OVRD/Exhaust Fan INOP/Fire Detected) Heated By Exhaust Air from The FWD Equipment Cooling System, Most Of The Air Is Distributed Beneath The Cargo Floor. Cargo Exhaust Air Is Then Discharged From The FWD Outflow Valve. A target temp of 21 degrees C is commanded
AFT Cargo Compartment
- No Temp Control
Heated Through The Exhaust Of The AFT ECS That Enters Beneath The Cargo Floor.
Bulk Cargo Compartment
- Automatic Overheat Protection
- A Target Temp of 21°C Is Commanded
Ventilation And Heating Are Primary Provided By The Cabin Air Passing Through A Supply Fan, An In-Line Electrical Heater And Heat Entering Below The Cargo Floor Of The AFT Cargo Comp. If An Automatic Shutdown Occurs The Cargo Heat Can Not Be Restored In Flight. The AMBER OFF light means (Exhaust Fan INOP/Supply Vent Valve Closed/Fire Detected)
FWD EQUIP COOLING
In OVRD Mode In Case Of, (Both Equipment Cooling Supply Fans Failed/Both Flow Sensors failed/Low Air Flow Detected/Excessive Temp Detected/Smoke Detected/ Equipment Cooling Sys/FWD Cargo Fire Armed)
OFF
Equipment Cooling Fans And Vents Are Command Off, Both The Smoke/Override Valves And the Flight Deck Isolation Valve Are Commanded Open. Cargo Heat Becomes INOP & OVRD illuminates.
OVRD
The System Is Isolated, All Fans Are Commanded Off, And All Valves Are Closed. The OVRD Valve Opens And Allows Differential Pressure To Create A Reverse Flow Of Air Across The Equipment And Overboard. The OVRD Mode Supplies Adequate Cooling In Cruise, But Airflow Reduces At Lower Altitudes.
AFT EQUIP COOLING
In OVRD Mode In Case of, (Both Equipment Cooling Supply Fans Failed/Both Flow Sensors failed/Low Air Flow Detected/Excessive Temp Detected/Smoke Detected/ Equipment Cooling Sys/ Cargo Fire Armed)
OFF
Equipment cooling Fans And Vents Are Command Off. The Override Valve is Commanded Open. Cargo Heat Becomes INOP & OVRD illuminates
OVRD
The System Is Isolated, All Fans Are Commanded Off, And All Valves Are Closed. The OVRD Valve Opens And Allows Differential Pressure To Create A Reverse Flow Of Air Across The Equipment And Overboard. The OVRD Mode Supplies Adequate Cooling In Cruise, But Airflow Reduces At Lower Altitudes
Two Positive Relief Valves
Operate In Case Of Negative Differential Pressure Encountered During A High Rate Of Descent
Sudden Loss Of Pressurization
In Case Of A Sudden Loss Of Pressurization The Outflow Valves Will Close Immediately In An Attempt To Control The Cabin Pressure, They Will Remain Closed Until The Aircraft Reaches 15000 feet. When The Aircraft And Cabin Altitude Are Equal, The Outflow Valves Open For The Reminder Of The Flight To Protect The Aircraft Against Negative Pressure.
Standby Cooling Mode
For Certain Malfunctions, Pack Control Automatically Uses Standby Cooling Mode As A Backup To The Normal Mode.
An EICAS Advisory PACK MODE (L, R) and STBY COOLING Is Displayed On The AIR Synoptic. In Standby Cooling Mode, Pack Cooling May Be Less Than The Normal Mode And Therefore Resulting In A Warm Flight Deck Or Cabin Temperature On Low Altitudes. If Only One Pack Is In STBY Cooling, It Will Shut Down At Lower Altitudes With Higher Ambient Temperatures.Example A Failure Of The Air Cycle Machine, The Pack Automatically Shifts To The Standby Cooling Mode, By Bypassing The ACM And Only By Using The Heat Exchanger To Cool The Hot Air.