Hydraulics Flashcards
What are the functions of the AUX hydraulic pump switch
ON
OFF
OVRD
The AUX pump, in the RIGHT system, provides an additional source of hydraulic pressure for both systems
Pump operation is controlled by the pump(AUX) switch located on the FOs instrument panel
1. ON - turns on electrical HYD Aux pump
2. OFF - turns off elec. HYD aux pump
3. OVRD - (momentary, must be held in position) bypasses thermal protection and activates pump
What protection does the Aux pump have?
A thermal switch that automatically shuts it off in the normal operating temperature range is exceeded
What are the functions of the hydraulic transfer pump switch?
- It opens/closes shutoff valve on each side of the transfer pump switch
- Transfer pump mechanically connects left/right HYD systems and enables hydraulic pressure to be transferred from the highest to lowest side
The hydraulic pump transfer pushes fuel how
High pressure side operates as a motor and the low pressure side acts as a pump
What does the illuminated HYD QTY low light mean, before and after Engine start for the MD88 and MD90
MD88 - Amber HYD QTY low lights on sys display panel illuminates when the left quantity is less than 8 qts OR right side less than 9
- after Engine start if either is below 4 than light illuminates
MD90 - same as above but left side 9 qts OR right side 10 qts
- after Engine start if either are below 6 qts
During electric failures, do the engine driven hydraulic pumps operate
Yes and in fact, they operate regardless of switch position
Minimum hydraulic quantity for dispatch
88 and 90
MD88- left 8, right 9
MD90- left 9, right 10
How many independent hydraulic systems are there and how are they designed
2 independent systems (left/right) utilizing fire resistant hydraulic fluid
Will the engine driven hydraulic pumps continue to operate during complete electrical failure
Yes, regardless of Switch position
How are the hydraulic systems named
Left and right
Note: the aux pump is in the right system and is not a system itself
