Hydraulic System Flashcards
When do the SPUs operate?
Number 1 system when switched from Norm to 1.
Number 2 system in ARPS aircraft when manually turned on,
SPUs will also turn on if in norm position and more than 0 flap selected.
If output pressure from engine driven pump falls below 2000PSI or if return pressure falls below 20PSI.
What does the #1 or #2 HYD FLUID HOT caution light tell you?
hydraulic fluid in the respective reservoir temperature exceeds 109 degrees c
What does the #1 or #2 ENG HYD PUMP caution light tell you?
the engine pump hydraulic output pressure has fallen below 2000PSI
What does the #2 SPU AUX PWR caution light tell you?
One of the variable frequency power sources to the SPU has failed
What does the #1 or #2 STBY HYD PUMP HOT caution light tell you?
over temperature in the electrical windings of the respective standby hydraulic pump
What does ARPS stand for?
Alternate Rudder Power System
What happens to the hydraulic system when you pull the ‘ pull fuel off’ handle?
the emergency shut off valve closes shutting down fluid supply to the engine driven pump.
in what 2 circumstances does the PTU automatically operate. When would you manually turn on the PTU?
Following loss of oil pressure in the number 2 engine and when retracting the undercarriage. Manually turn on to extend undercarriage following number 2 engine failure in flight.
What does the PTU supply power to on the ARPS and RHIS? Are there any restrictions on how long you can operate the PTU?
ARPS the PTU can power the entire number 2 hydraulic system with no time restriction
RHIS the PTU can only supply hydraulic pressure to the landing gear extension and retraction system and has a 5 minute restriction.
On the RHIS what does the rudder isolation valve do? When and how does this occur?
The valve isolates the rudder actuater, engine driven pump and SPU from the rest of the system. This occurs when the fluid quantity in the respective system falls below 0.7 Quarts. A reservoir low level switch closes the valve.
What caution light will illuminate on RHIS modified aircraft when the isolation valve is closed by the reservoir low level switch?
1 or #2 HYD ISO VLV
Following a number 1 hydraulic system failure, why is there a 200kt airspeed restriction?
Due to a rudder limitation
What rate and pressure do the engine driven pump and SPU provide?
Engine driven is constant pressure (3000PSI) variable flow
SPU is constant flow, variable pressure
Where are the SPUs located in an ARPS system?
Number 1 is in the engine nacelle.
Number 2 is mid spar on the vertical fin
How are hydraulic pressure reservoirs pressurised?
Through the differential piston which receives 3000PSI from the engine driven pump
