pneumatic systems Flashcards
what are the two basic types of air pumps (compressors)?
wet and dry
wet air pumps use ______ ___ to lubricate inside of pump
wet air pumps use ENGINE OIL to lubricate inside of pump
dry air pumps (more common) have _______ vanes inside pump housing which self lubricate as vane rotates
dry air pumps (more common) have GRAPHITE vanes inside pump housing which self lubricate as vane rotates
air is filtered as it is down into each compressor, an is discharged into the system through and oil and ______ trap, a _________, a ______ and a non-return valve
air is filtered as it is down into each compressor, an is discharged into the system through and oil and WATER trap, a DEHYDRATOR, a FILTER and a non-return valve
in pneumatic compressors, the volume of each successive stage is _______ than the preceding one and compression takes place
in pneumatic compressors, the volume of each successive stage is SMALLER than the preceding one and compression takes place
in pressure regulators, when system maximum pressure is reached, the air pressure acting upon the piston produces a force greater than the spring and _____ _____ air pressure and so the ball valve opens, providing a path to atmosphere for the third stage air
in pressure regulators, when system maximum pressure is reached, the air pressure acting upon the piston produces a force greater than the spring and THIRD STAGE air pressure and so the ball valve opens, providing a path to atmosphere for the third stage air
in dehydrators, the air is thoroughly dried by passing it through a desiccant, such as _________ ________
in dehydrators, the air is thoroughly dried by passing it through a desiccant, such as ACTIVATED ALUMINA
in pressure maintaining valves. this valve will allow pressure to the ________ or ESSENTIAL operating systems at all times, closing off pressure to the SECONDARY or ___-________ systems should power system pressure fall below a pre determined level
in pressure maintaining valves. this valve will allow pressure to the PRIMARY or ESSENTIAL operating systems at all times, closing off pressure to the SECONDARY or NON-ESSENTIAL systems should power system pressure fall below a pre determined level
isolation valves are ________ operated valves designed for use by maintenance personnel
fitted _________ of the storage cylinders, they are normally wire locked in the _____ position, when closed they will allow maintenance downstream of the valve without the need to release storage cylinder pressure
isolation valves are MANUALLY operated valves designed for use by maintenance personnel
fitted DOWNSTREAM of the storage cylinders, they are normally wire locked in the OPEN position, when closed they will allow maintenance downstream of the valve without the need to release storage cylinder pressure
WARNING. when operated, the isolation valve may give maintenance personnel the impression that the system is __________. the power system may however, contain full system pressure and extreme care is necessary to prevent injury to personnel
WARNING. when operated, the isolation valve may give maintenance personnel the impression that the system is DEPRESSURISED. the power system may however, contain full system pressure and extreme care is necessary to prevent injury to personnel
pneumatic system actuators will convert the energy of compressed air into ______ or ______ movement and force. pneumatic actuators are often ________ to prevent too rapid movement.
pneumatic system actuators will convert the energy of compressed air into LINEAR or ROTARY movement and force. pneumatic actuators are often DAMPED to prevent too rapid movement.
pneumatic actuator damping is achieved by forcing ______ through at the annular space between the inner wall of the piston rod and a stationary damper piston.
an orifice and plate valve in the damper piston provides ____ damping when the piston rod retracts than when it extends, this will slow the rate of undercarriage lowering
pneumatic actuator damping is achieved by forcing GREASE through at the annular space between the inner wall of the piston rod and a stationary damper piston.
an orifice and plate valve in the damper piston provides LESS damping when the piston rod retracts than when it extends, this will slow the rate of undercarriage lowering
in engine bleed air pneumatic systems, the main supply of compressed air is provided by the ___ pressure/_________ stages of the engine compressor
at reduced power settings the ____ stage valve will open to allow the high-pressure compressor to satisfy the demands of the user system
in engine bleed air pneumatic systems, the main supply of compressed air is provided by the LOW pressure/INTERMEDIATE stages of the engine compressor
at reduced power settings the HIGH stage valve will open to allow the high-pressure compressor to satisfy the demands of the user system
the pressure regulator and shut off valve (PRSOV) is a pressure actuated electrically controlled valve and has 4 functions:
- opens and closes in response to the control switch on the bleed air control panel in the crew compartment, or when temp and pressure limits are exceeded. it will also close when the engine fire handle is operated to arm the extinguisher circuit
- prevents reverse flow when dict pressure exceeds engine supply pressure
- modulates to limit pressure in the pneumatic manifold to approximately 45 psi
- limits temp to 230 celsius
pre cooler, also known as a ____ ________, cools bleed air to 200 - 230 celsius
pre cooler, also known as a heat exchanger, cools bleed air to 200 - 230 celsius
a pneumatic ground service connector and _____ valve are provided for the connection of a ground service trolley
the check valve prevents loss of air through the connection during normal operation of the aeroplane bleed air system; a secondary seal may be provided by a ________ cap fitted to the connection to prevent ingress of dirt and moisture
a pneumatic ground service connector and CHECK valve are provided for the connection of a ground service trolley
the check valve prevents loss of air through the connection during normal operation of the aeroplane bleed air system; a secondary seal may be provided by a BLANKING cap fitted to the connection to prevent ingress of dirt and moisture
the APU bleed valve is fitted downstream of the APU in the air ducting, when the APU is operating above __% RPM the bleed valve can be opened to supply air to the system
the APU bleed valve is fitted downstream of the APU in the air ducting, when the APU is operating above 95% RPM the bleed valve can be opened to supply air to the system
the APU bleed valve will be close automatically if the APU ____-_______ switch is operated to arm the fire extinguisher
the APU bleed valve will be close automatically if the APU FIRE-WARNING switch is operated to arm the fire extinguisher
automatic leak detection systems comprise of ____ sensitive devices fitted around _______ runs to alert the flight crew of a leak or rupture of the ducting
automatic leak detection systems comprise of HEAT sensitive devices fitted around DUCTING runs to alert the flight crew of a leak or rupture of the ducting
heat sensitive leak detection elements comprise of an electrical conductor encapsulated in a earthed metal tube. between the conductor and earth is a material whose electrical resistance is _________ proportional to temperature. i.e. the higher the temperature, the lower the resistance
heat sensitive leak detection elements comprise of an electrical conductor encapsulated in a earthed metal tube. between the conductor and earth is a material whose electrical resistance is INVERSELY proportional to temperature. i.e. the higher the temperature, the lower the resistance
in some aeroplanes, spot detector heat sensors are also incorporated, these operate on the principle of the __-________ strip
in some aeroplanes, spot detector heat sensors are also incorporated, these operate on the principle of the BI-METALLIC strip
DO NOT check for leaks using _____ hands
DO NOT check for leaks using BARE hands
at normal temperatures, phosphate ester based hydraulic fluid (skydrol) is compatible with titanium
at temperatures above 130 celsius the fluid becomes ______ and attacks titanium, causing it to corrode and become brittle
this will be evident through bright glossy ______ or a dull _____ residue and must be treated in accordance with the manufacturers instructions
at normal temperatures, phosphate ester based hydraulic fluid (skydrol) is compatible with titanium
at temperatures above 130 celsius the fluid becomes ACIDIC and attacks titanium, causing it to corrode and become brittle
this will be evident through bright glossy BROWN or a dull BLACK residue and must be treated in accordance with the manufacturers instructions
certain pneumatic ducting damage may be repairable but the AMM must always be consulted for inspection, repair and test.
generally, the following will apply:
- smooth dents permissible providing they do not _______ the flow of air through the duct
- shallow scratches and gouges permissible if they are not more than __% of wall thickness and providing bottom of scratch is smooth
- any defect within 1/4” or _mm of a weld renders duct US
certain pneumatic ducting damage may be repairable but the AMM must always be consulted for inspection, repair and test.
generally, the following will apply:
- smooth dents permissible providing they do not RESTRICT the flow of air through the duct
- shallow scratches and gouges permissible if they are not more than 10% of wall thickness and providing bottom of scratch is smooth
- any defect within 1/4” or 6mm of a weld renders duct US
