CHAPTER 36 Flashcards
What stage supplies the bleed air when engines are at low power?
The High Pressure Bleed Valve (HPV) supplies air to the system when
the engines are at low power.
What happens if the the engine bleed if the pressure is too high?
Each Bleed Monitoring Computer (BMC) monitors the system pressure and will stop the engine bleed if the pressure is too high. An Overpressure Valve (OPV) is also installed downstream from the bleed valve as a protection of the system if the pressure is too high.
How is the temperature of the engine bleed air is regulated?
The hot bleed air goes through a precooler. Fan discharge air, modulated by the Fan Air Valve (FAV), is blown across the pre-cooler to keep the temperature within limits.
What is the purpose of the cross bleed valve?
The left and right bleed systems are connected by a cross bleed duct. A cross bleed valve is used for their interconnection or isolation.
On the ground, how can the right side pneumatic system be supplied?
On the ground, a HP ground power unit can be connected to the left
side pneumatic system. The right side can be supplied by opening the cross bleed valve.
What are the pressure regulation components on the engine?
Engine High Pressure Valve (HPV)
Engine BLEED PRV
OPV (normally open)
What are the temperature regulation components fitted on the engine?
FAV and Precooler.
How is APU bleed fed to the aircraft?
It is connected to the cross bleed duct in the forward belly fairing area.
What pressure does the PRV try to maintain?
The PRV pneumatically regulates the bleed pressure around 44 psi
How does the Overpressure Valve (OPV) operate during an over pressure?
The Overpressure Valve (OPV), which is normally open, closes
pneumatically. The OPV starts to close at 75 psi. It is fully closed at 85 psi and opens again at around 35 psi.
When the engines are shut down how is the pneumatic system closed down?
When the engines are shut down, the PRV, Fan Air Valve (FAV) and HP VLV are spring loaded closed due to the lack of air pressure.
If a BMC 1 fails what would happen to control of the system?
The monitoring of main parameters such as High Pressure (HP) Valve (VLV), PRV, heat exchanger outlet temperature sensor, and regulated pressure transducer, is undertaken by BMC 2, but the automatic control of the No1 engine PRV is lost.
Which BMC is connected to loops A?
The wing loops A are connected to BMC 1 and wing loops B to BMC 2.
Can the aircraft be dispatch with a fault of the HPV?
In case of failure, the pneumatic system HPV must be deactivated
CLOSED for dispatch per Minimum Equipment List.
To generate a WING LEAK fault what must happen?
The WING leak detection is a dual-loop system. To generate a WING LEAK warning, both A and B loops have to detect the overheat.
Can the aircraft be dispatch with a fault of a single wing loop?
For dispatch, WING leak detection must be operational (at least one loop) on each wing.
