b767 air conditioning

Copyright Smartcockpit.com Ludovic ANDRE / version 00

Smartcockpit.com

BOEING 767 SYSTEMS REVIEW

AIR CONDITIONING

1. GENERAL ¡¡ Air conditioning is achieved by 2 identical PACKS, each of which controlled by a PACK CONTROL

SELECTOR. ¡ Positioning the selector to AUTO or STBY sends an open signal to the PACK VALVE. ¡ Conditioned air from the packs flows into a common manifold where it mixes with air from 2 RECIRCULATION

FANS. The mixed air is then ducted into the temperature controlled compartments of the airplane.

2. PACKS

¡¡ Pack switch on AUTO : temperature control is automatic

¡¡ Pack switch on STBY : - N set pack for constant MODERATE temperature - C set pack for COLD operation* - W outlet temperature controlled by RAM AIR flowing across the heat exchangers* (* from 18°C to 30°C). ¡¡ HIGH FLOW when : Ô ground operation when APU or GND air supplies the system

Ô in flight when : - 1 PACK OFF or - 1 RECIRC. FAN U/S or OFF

¡¡ HIGH FLOW inhibited when Ô using WING A/I and only 1 Bleed.

Ô one engine INOP Ô FLAPS not in UP position

Ô aft cargo compartment ARMED switch pushed INOP : - Automatic control fault Ô Pack temperature valves freeze in the last (amber) controlled position. Pack cannot be reset and must be operated in STBY. INOP light + EICAS message go out when the Pack selector is rotated to a STBY position. - Overheat (internal or air leaving the pack) Ô Pack automatically set and locked to max cooling. After cooling, the Pack can be reset for automatic or standby operation by pushing the PACK RESET switch INOP light go out when the Pack selector and the Pack returns to the Selected control at reset. PACK OFF : - Pack valve closed due to : - pack shut down - selector OFF

- loss of bleed air - overheat ¡ ONE reset, then set MANUAL 3. PACK VALVE ¡¡ The PACK VALVE is a flow control valve and requires air pressure to open. When open, the valve controls air

flow to a scheduled rate based on airplane altitude.

INOP

PACK OFF

L/R PACK


Smartcockpit.com


4. RECIRCULATION FAN ¡ Left & Right Recirculation Fans draw air which has been exhausted from the cockpit & passengers cabin through

filters and returns the air to the mix manifold. There it mixes with conditioned air from the packs and is distributed again to the cabin.

¡ Purpose of recirculating cabin air is to maintain the desired level of passenger cabin ventilation while minimizing

the use of bleed air. ¡ Recirculation Fans may be turned OFF several minutes to refresh the air in the cabin.

- ON : Recirculation fan signalled ON - INOP (amber) : Recirculation fan switch is OFF or the fan has failed + EICAS msg. 5. TEMPERATURE CONTROL ¡ The airplane is divided into 4 compartments for temperature control : - the flight deck - the FWD 1/3 cabin - mid-cabin - aft cabin ¡ Temperature controller signals the pack to produce air for the compartment requiring the coolest ¡ Trim air system then adjust the others (with air from downstream the pack valve) TRIM AIR - ON : Trim air regulating valve signalled open - OFF (amber) : trim air switch is OFF + EICAS msg + 4 compartments INOP lights ON Packs then provide air for a 24°C cabin temperature - - Duct temperature overheat (amber) - Fault in the associated compartment temperature control system - Associated Passenger Compartment temperature Control OFF - Trim air OFF ¡ Setting the compartment selector to OFF, closes the respective Trim air & temperature is then controlled by the

coolest compartment 6. CREW HEAT ¡ Additional electrical heater for each pilot usable IN FLIGHT only (side window & rudder pedal areas)

ON

INOP

ON

OFF

INOP


Smartcockpit.com


AIR CONDITIONING


Smartcockpit.com


CABIN TEMPERATURE CONTROL


Smartcockpit.com


LEFT PACK LOGIC

b767 air conditioning

Documents