Chapter 1.3: Hydraulic Reservior and Pump

Question 1

what are baffles and fins in reservior for?

Answer 1

prevent swirling and surging of fluid (may cause fluid to foam and air to enter the pump)

Question 2

what are non-pressurised and pressurised reservoir used for?

Answer 2

non-pressurised - low altitude or non-violent flight maneuver

pressurised - high altitude and/or violent maneuver flights (ensure +ve flow of fluid to pump)

Question 3

what do pressurised reservoir prevent?

Answer 3

fluid foaming and cavitation

Question 4

types of pressurised reservoir

Answer 4

1) hydraulic pressurised
2) air pressurised

Question 5

how does a hydraulic pressurised reservoir work?

Answer 5

pump pressure applied to moveable piston inside reservoir, which is attached to move larger piston

Question 6

how does air pressurised reservoir work?

Answer 6

engine bleed air or air from pneumatic system is used to pressurise reservoir

Question 7

what is a hydraulic pump?

Answer 7

mechanical source of power that converts mechanical or electric power to hydraulic energy

Question 8

how are hydraulic pumps driven?

Answer 8

1) aircraft engine driven
2) ram air turbine
3) hand
4) electric

Question 9

what is a constant displacement pump?

Answer 9

supplies fixed quantity of fluid during each revolution of pump regardless of pressure demand

Question 10

types of constant displacement pumps

Answer 10

1) gear-type power pump
2) gerotor pump
3) axial inline piston pump

Question 11

how does an axial inline piston pump work?

Answer 11

drive shaft connected to engine is connected to swash plate with pistons

Question 12

what is a variable displacement pump?

Answer 12

• a pump that does not require pressure unloading valve
• fluid output can be varied to meet pressure demand of the system

Question 13

purpose of filter unit?

Answer 13

clean hydraulic fluid, prevents FOD and contaminating substances from accumulating in system

Question 14

what does a filter unit consist of

Answer 14

1) filter house,
2) bowl,
3) filter element,
4) bypass relief valve,
5) pressure difference indicator

Question 15

what are the 3 filter units?

Answer 15

1) pressure filter
2) return filter
3) case drain filter

Question 16

what does the pressure filter do?

Answer 16

filter debris or small particles that can flow from the hydraulic pump

Question 17

what does return filter do?

Answer 17

filter debris or small particles before the oil returns to the reservoir

Question 18

what does case drain filter do?

Answer 18

filter debris or small particles the oil used for lubrication and cooling of pump

Question 19

contamination to hydraulic fluids

Answer 19

1) abrasive particles
2) non-abrasive particles
3) intermixing of fluid

Question 20

2 types of commonly used filter element

Answer 20

porous paper & wire gauze

Question 21

what should be doen when oil sampling check does not pass or suspected to be contaminated?

Answer 21

1) flushing of entire system
2) replace all filters