Download - B767 Pneumatics
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 1/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 1
PNEUMATICS
1. GENERAL
¡ Air for Ô Air conditioning & pressurizationÔ Wing & Engine anti-iceÔ Engine startÔ Cargo heatÔ Center hydraulic system ADP (Air Driven Pump)Ô Hydraulic Reservoir Pressure
2. ENGINE BLEED AIR SUPPLY
¡ Left & Right engine bleed air supplies are similar & pneumatics energy comes either from :- High Pressure (HP)- Low Pressure (LP)
¡ Low thrust = HP valve open.High thrust = HP valve closed.
¡ Bleed Air valves are used for pressure control and :- are electrically commanded- are pressure actuated- close during period of low air demand.
3. PNEUMATIC DUCTING
¡ Normal flight procedures require isolation between Left and Right systems after engine start :- Each engine supplies air to its corresponding Air Cond. Pack, Wing Anti-ice, Thrust reverser & Hydraulic
reservoir.- Both engines supply air to the Center pneumatic duct.- Separation of the system is controlled by the L & R isolation valves controlled by the L & R Isol. Switches.- A bypass around each isolation valve allows airflow from the engine for FWD cargo compartment heat &
to supply the Center pneumatic duct.
¡ The pressures read on the Pneumatic Duct Pressure Indicator should be approximately equal
¡ Center Isolation switch controls Bleed airflow into or out of the Center pneumatic duct. The switch is ON fornormal operation.
¡ After engine start, air is bypassed around the L & R isolation valves into the crossover manifold & theninto the Center pneumatic duct for distribution to the using systems :- Center hydraulic system demand Air Driven Pump (ADP)- Aft cargo compartment heat- Bulk cargo compartment heat- Center hydraulic reservoir
Engine compressor section
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 2/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 2
4. APU BLEED AIR SUPPLY
¡ APU is connected to the pneumatic system through the APU Bleed Air Valve :- VALVE light illuminates momentarily indicating a disagreement while the valve is in transit.
- Opens with APU at normal speed through the Center pneumatic duct.- Closes after the first engine start.- Reopens during the start cycle of the other engine.- With engines running, cannot be opened unless Center isolation valve closed & both engine bleed valves
closed (Check valve in the center duct + APU bleed Air Valve).
¡ Barometric control of APU components automatically reduces APU pneumatic pressure and results in insufficientpressure for cabin pressurization > 20.000 ft.
5. GROUND PNEUMATIC SUPPLY
¡ 2 ground connectors on the Left side of the a/c permit 2 Packs operation or engine start.
¡ L + R ISLN switches should be ON for : - air conditioning pack- engine starting
6. DUCT LEAK TEST
¡ Checks the continuity of the leak detector loops.
¡ Illumination of the three DUCT LEAK + EICAS Caution messages = no fault
¡ BODY DUCT LEAK msg is a leak in the CENTER duct.
7. ENG STRUT LEAK TEST
¡ Checks the continuity of the detectors and simulate a strut leak.
¡ Illumination of L&R DUCT LEAK lights + EICAS Caution message = no fault.
¡ Releasing the switch terminates the test. For resetting the system, Engine Bleed Air switches must be cycledto unlatch the PRV & HPSOV and return to normal operation.
8. FAULTS
L/R ISLN
- ON (alternate action) : opens Isolation Valve- VALVE (amber) : Isolation Valve position disagrees with switch signalled position.
VALVE
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 3/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 3
APU
L/R ENG
- ON (alternate action) : opens engine bleed air valves if engine is operating- OFF (amber) : engine bleed air valve closed + EICAS msg.
- Bleed air leak in the Left, Right or engine strut pneumatic duct + EICAS msg.(amber) or
- system testÔ Bleed air and isolation switches to be selected OFFÔ in case of Bleed duct leak = back to normal when the temperature has cooledÔ if the light remain ON, a leak exists between the L and R isolation valvesÔ Strut duct leak = light remain illuminated
(amber) : Engine HPSOV (High Pressure Shutoff Valve) and/or Pressure Regulating valvesare open when they should be closed + EICAS msgÔ BLEED + Eng. HPSOV = the HPSOV is open when only low pressure is requiredÔ BLEED + Eng. PRV = the pressure regulating valve has failed open
- Engine Bleed Air over temperature + EICAS msg(amber) and
- Engine Bleed air valves are automatically closed + EICAS msgÔ OVHT gives a signal to close the engine bleed valve > idem for PRV and HPSOVÔ unless strut duct leak exist : - PRV reopens with engine anti-ice
- HPSOV and PRV reopens for Thrust reverserÔ reset = BLEED AIR SWITCH ON and OFF A only one reset recommended.
- Bleed air leak in the centre pneumatic duct + EICAS msg(amber) or
- System test + EICAS msg
VALVE
ON (amber) : APU bleed air valve disagrees with signalled position.
OF
F
ON
DUCTLEAK
BLEED
OVHT
D LU EC A
T K
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 4/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 4
PNEUMATICS SYSTEM (PW)
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 5/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 5
PNEUMATICS SYSTEM (GE)
8/13/2019 B767 Pneumatics
http://slidepdf.com/reader/full/b767-pneumatics 6/6
Copyright© Smartcockpit.comLudovic ANDRE / version 00
Smartcockpit.com BOEING 767 SYSTEMS REVIEW Page 6