11.11 Emergency Pressure Flashcards
what is generally used incase the engine driven pumps fail in a hydraulic system ?
alternating current motor pumps, RAM air turbine , Power transfer unit or a ground power unit
what are the three uses for emerency and backup pressurisation?
- to help the main pressurisation if there is high user demand
- to replace the main pressurisation when a fault occurs
- for mainenance purposes on the ground when the engines are not running
what is a RAM AIR TURBINE ( RAT) ?
a variable displacement pump that is installed in the aircraft to provide electrical and hydraulic power if the primary sources are lost
one the RAT has deployed, how can it be retracted?
hydraulically retracted, however it can only be done on ground
how can the RAT be deployed ?
automatically or by a button in the flight deck
how can the RAT be prevented from coming out of its housing during maintenance ?
circuit breakers should be pulled or a safety lock pin.
what is important to remember about the operation and drive of a power transfer unit?
some can come in uni directional, others in bi directional. some are variable displaceent and others are positive displacement only
what is the role of a power transfer unit ?
to allow operation of the hydraulic system in case of normal operational failure
what are the two units inside a PTU?
hydraulic pump and a hydraulic motor connected through a drive shaft
how can a PTU be operated?
either comes on automatically or manually
what is an AMCP?
AC motor pump- a nine piston variable displacement pump
in what situations can an ACMP be used?
as a primary source, emergency or backup source of pressurisation
how is an ACMP kept cool during operation?
either cooled by air or hydraulic fluid circulated through the motor
how is an ACMP kept cool during operation?
either cooled by air or hydraulic fluid circulated through the motor
