Simulator Integration Planning: ATA 21 - Air Conditioning and Pressurization

ATA 21 is the Systems chapter for Air Conditioning and Pressurization (a complete listing of ATA chapter numbers can be found here). I decided to work through the simulator system integration according to the ATA chapters and that way everything stays in a somewhat logic order. The upper panel of the flight engineer console on the L-1011 is largely consumed by control and indicator elements for ATA 21 and ATA 36 (which is Pneumatic).

Below are images from the original documentation of the L-1011 simulator created by Singer Link Division in the 1980s.

Environmental Control System (ECS) Monitor Panel (*791/A9)

The simulator implements all component pieces of the ECS monitoring panel.

L-1011 Trainer - ECS Monitoring System (Component Labels)

Implemented Components

Gauges
M10 ... Pack Flow 
M11 ... ECS Temperature
M12 ... Cabin Temperature

Switches
S10 ... Pack Select 
S11 ... ECS Temperature Select 
S12 ... Cabin Zone Temperature Select    

Switch Lights
SDS26 . Cool Air Overboard
SDS27 . Cargo Heat Forward
SDS28 . Cargo Heat Mid
SDS29 . Cargo HEat Aft
SDS30 . Instrument Cooling

Annunciators
DS14 .. Avionic Air Forward
DS15 .. Avionic Air Mid

Cabin Pressurization (*791/A9)

Several of the gauges for the pressurization panel are photo simulations on the original Singer Link Division L-1011 simulator. These instruments will be replaced with the real flight hardware as part of the simulator outfit at the museum. However, several switch and annunciator elements are already fully implemented.

L-1011 Trainer - Pressurization (Component Labels)

Implemented Components

Gauges

M1  ... Forward Outflow Valve 

M2  ... Aft Outflow Valve

Switches

S1  ... Forward Outflow Valve Manual Control 

S2  ... Aft Outflow Valve Manual Control 

S9  ... Cabine Altitude Horn Cutout

Switch Lights

SDS1 .. Forward Outflow Valve Manual/Automatic

SDS2 .. Aft Outflow Valve Manual/Automatic

Annunciators

DS12 .. Forward Safety Valve 

DS13 .. Aft Safety Valve

Cabin Temp Control (*791/A9)

The Cabin Temperature and Engine Bleed Control panels are combined. The lower portion of the panel is the cabin temperature control panel. For the ATA 21 integration we will only cover the lower portion of the panel. 

Implemented Components

Gauges
M4  ... #1 Turbine Bypass Valve Position 
M5  ... #1 RAM AIR Valve Position
M6  ... #2 Turbine Bypass Valve Position 
M7  ... #2 RAM AIR Valve Position
M8  ... #3 Turbine Bypass Valve Position 
M9  ... #3 RAM AIR Valve Position

Switches
S1  ... #1 Valve Cool
S2  ... #1 Valve Warm
S3  ... #2 Valve Cool
S4  ... #2 Valve Warm

S5  ... #3 Valve Cool
S6  ... #3 Valve Warm

S7  ... Area Overheat

S8  ... Area Overheat Test

Switch Lights
SDS10 . #1 Pack Flow Control
SDS11 . #2 Pack Flow Control 
SDS12 . #3 Pack Flow Control
SDS13 . #1 Valve Control Auto and Manual
SDS14 . #2 Valve Control Auto and Manual
SDS15 . #3 Valve Control Auto and Manual
SDS16 . Left Hot Air 
SDS17 . Right Hot Air
SDS18 . Left Isolation Valve
SDS19 . Right Isolation Valve
SDS20 . Ground Cont
SDS21 . Flight Station Open Close
SDS22 . Forward Cabin Open Close
SDS23 . Mid Cabin Open Close
SDS24 . Aft Cabin Open Close
SDS25 . Galley Open Close

Annunciators
DS7 ... Area A Overheat
DS8 ... Area H Overheat
DS9 ... Area B Overheat 
DS10 .. Area C Overheat
DS11 .. Planum Duct Overheat

L-1011 ECS: Cold Air Plenum (21-14)

Outputs from all three air conditioning packs discharge through a check valve and into a common chamber called the cold air plenum.

The cold air plenum is a rectangular box which receives air from the three air conditioning packs, then mixes and distributes the available air to the four aircraft zones. The plenum is decided down its whole length by a perforated baffle. The air from packs 2 and 3 and approximately 60% of pack No. 1 air is mixed together for distribution to the three cabin zones. The other 40% from pack No. 1 is diverted by another baffle which directs the supply towards the flight station outlet duct.

The plenum is located at the rear right hand side of the FESC.

L-1011 ECS: Cabin Airflow (21-13)

The conditioned air is distributed throughout the cabin zones from ducting that runs up the forward right side of the fuselage to three supply ducts located above the passenger cabin ceiling. The air entered the cabin zones through aspirator units that are attached on the bottom side of the distribution ducting. This creates circulation of the air by mixing existing cabin air with the incoming conditioned air. The total volume of air in the cabin is changed approximately every 4 minutes. The cabin air then exhausts through grills in the sidewalls of the cabin floor venting down through the lower compartments before passing overboard through the pressurization outflow vales. 

L-1011 ECS: Pack and Temperature Control

The control and operation for the air conditioning pack system and the zone trim system is accomplished from the lower half of the engine bleed cabin temp control panel (aka. ECS panel). The operation of each system is automatic. In case the automatic function fails,t here is a manual control for pack and zone temperature operation. 

Original Flight Hardware: Cabin Temperature Control (Sub-Panel)

This posting covers the second of 4 sub-panels of the large pneumatics panel on the Lockheed L-1011. The panel is titled "CABIN TEMPERATURE CONTROL" and controls the hating and cooling of the vehicle interior (except for the cargo area).

The three air conditioning packs (as seen below) are located in unpressurized compartments on either side of the nose-wheel well. The packs utilize Air Cycle Machines (ACMs) that are operated by compressed bleed air.



Compressed air from the Pack Flow Control valve is partially cooled by the primary heat exchanger. This air is routed to the ACM compressor and, in the case of the #2 and the #3 packs, through a check valve to mix with hot air from the hot air distribution system. The partially cooled air may also pass through another check valve directly to the secondary heat exchanger when the air pressure is greater than ACM compressor discharge pressure.

The cooled air from the ACM turbine and from the Turbine By-Pass Valve are routed through a water separator tot he cold air plenum for distribution to the various zones. Ambient outside air is use for cooling the heat exchangers and is exhaust overboard through exit louvers for each pack. The louvers open and close automatically (during AUTO pack operation), or can be controlled manually (during MANUAL pack operation) to control pack discharge temperature.


Air for the cold air planum can also be supplied externally on the ground. The ground A/C connections feed directly into the #1 and #2 planum system.

The control elements for the PACK TEMPERATURE CONTROL are listed below:

• PACK FLOW CONTROL ... Controls pack flow control valve to schedule a constant mass air flow. Valve is energized closed and pressure opened. The illuminated flowbar indicates flow control valve is open. If OVHT is illuminated, the valve locks closed, flowbar is extinguished and associated hot air valve closes.
• TURB BYP INDICATOR ... Shows relative position of turbine bypass valve (TBV). Pointer moves to COOLER as TBV closes.
• PACK AUTO/MANUAL SWITCH .... If AUTO is illuminated. Ram air exit louvers and turbine bypass valves modulate automatically, to provide temperature control. Setting of zone temperature selectors control packs and zone trim valves to regulate the five zone temperatures. If MNL is illuminated. Arms COOL and WARM switches for manual control of ram air exit louvers and turbine bypass valve. The zone temp selectors control zone trim valves to regulate the five zone temperatures.
• HOT AIR VALVE SWITCH .. this switch opens and closes the control manifold for hot air to be mixed into the pack outflow.