Hydraulics Flashcards
How many hydraulic systems are on the airplane?
3 independent systems
HYD 1, 2 and 3
What systems use hydraulic power?
- Flight Controls
- Spoilers
- Landing gear
- nose wheel steering
- wheel brakes
- thrust reversers
Can hydraulic fluid be transferred between systems?
No
How many hydraulic pumps are on the airplane?
Six:
- 2 EDPs (engine driven pumps)
- 4 ACMP ( AC motor pumps)
What are the basic components of the hydraulic systems?
- reservoir
- pumps
- accumulator
What do accumulators do?
Maintain constant pressure and prevent pump cavitation
When will ACMP 1 or 2 activate automatically on the ground?
When flaps are > 0 and:
- TL set for takeoff, or
- GS > 50 kts
When will ACMP 1 or 2 automatically activate when in the air?
- engine failure or EDP failure
- flaps > 0
Name some important systems controlled by HYD 2
- Landing gear
- nose wheel steering
- inboard brakes
What is the PTU?
- power transfer unit
- mechanical pump that uses HYD 1 power to provide HYD 2 pressure
What is the primary purpose of the PTU?
To allow landing gear retraction in the event of an engine 2 or EDP 2 failure
When will the PTU automatically activate?
When engine 2 or EDP 2 fails and:
- Flaps > 0 or landing gear not up and locked
- EDP 1 not failed
- HYD 2 reservoir quantity > 12%
With ACMP 1 and 2 in AUTO how is single engine taxi on engine 1 possible if nosewheel steering is on HYD 2?
- releasing parking brake activates ACMP 2
What is the purpose of HYD 3?
Backup for the primary flight controls
What are HYD ACMP 3A and B pump switches ON and AUTO respectively?
- HYD ACMP 3A is primary and has no automation
- HYD ACMP is the backup and automatically activates if ACMP 3A fails