Engine HP Bleed Valves


  1. HP Valve
  • The HP Bleed Valve is a 4 in. dia. butterfly-type valve which operates as a shut-off and pressure regulating valve.
  • The HP bleed valve is normally spring-loaded closed in the absence of upstream pressure. A minimum pressure of 8 psig is necessary to open the valve.
  • The HP bleed valve pneumatically limits the downstream static pressure to 36 plus or minus 3 psig. It closes fully pneumatically when the upstream static pressure reaches 120 psig plus 5 psig or minus 10 psig.
  • A pneumatic sense line connects the HP bleed valve with the bleed pressure regulator valve (PRV) in order to make sure that the HP bleed valve will close when bleed pressure regulator valve is controlled closed.
  • A solenoid is installed in the fan compartment. It is connected by a sense line to the HPV-PRV coupling sense line.
  • Altitude over 15000ft the solenoid is energized by the Engine Electronic Controller (EEC). It opens to ambient the HPV-PRV coupling sense line which lets HPV controlled close pneumatically.


The HP bleed valve upstream pressure supplies chamber (1) of the regulator through a jet to control the position of the clapper (2) and maintain constant air pressure in the HP bleed valve actuator opening chamber.The test intake is used for checking correct valve operation on the ground by directly supplying the regulator.The HP bleed valve downstream pressure supplies the HP bleed valve actuator closing chamber through distribution clapper (3). Indeed when downstream pressure reaches the value determined by spring pre-loading.


reduced pressure air supplies chamber (4) of the opening/closing sub assembly though a jet to control the position of clapper (5) against its lower seat position and allow the HP bleed valve actuator opening chamber supply with reduced pressure air.When chamber (4) is vented to ambient the clapper (5) leaves its lower seat position and reduced pressure air is allowed to supply the HP bleed valve actuator closing chamber (by unseating the spring-loaded ball).

Fault Detection and Monitoring of the System

The monitoring system detects failures and abnormal operation of the engine bleed air supply system. It warns the crew and transmits the relevant information to the upper and lower ECAM display units. Additionally the MASTER CAUT light comes on and a single chime sounds. The system also enables abnormal operation and failure to be detected during flight in order to facilitate replacement on the ground of faulty components (Line Replaceable Units, LRU).

-Valves are fitted with position microswitches for monitoring.

-An exchanger outlet temperature sensor monitors the precooler outlet temperature.

-Two pressure transducers monitor the air pressure available in circuit.

(1)The two BMCs monitor the electrical signals from the microswitches of the valves, the temperature at the precooler outlet, the transferred and the regulated pressures. Additionally, they monitor ambient overheat in pylons, wings and the fuselage Ref. AMM D/O 36-22-00-00.

(2)The two BMCs transmit data through the SDAC to the ECAM system which generates the indications on the system page. The indications are : pressure, temperature and position of the main valves (PRV, HP Bleed Valve , CROSSBLEED and APU BLEED valve). The two BMCs signal directly to the AIR COND overhead control panel the ENG 1 (2) BLEED FAULT signal.

(3)The two BMCs trigger a warning in case of :-overpressure/low pressure-overtemperature/low temperature-ambient overheat.

(4)The two BMCs control the closure of the PRV (during warning, engine start, APU bleed) automatic mode of CROSSBLEED valve and APU bleed valve opening availability.

(5)The two BMCs monitor the correct operation of the whole system and detect abnormal function of an item. They send this data to the Centralized Fault Display System (CFDS) (Maintenance Computer).NOTE:All the class 1, 2 and 3 maintenance messages transmitted from the two BMCs are listed in the INDEX of the TSM.

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