MD-11 Flight Crew Operations Manual
k
Hydraulics -
Description and Operation
Hyd.10.6
Hydraulic Preflight Engine-Driven Pump Test
The hydraulic preflight engine-driven pump test, the second of two preflight tests
required to test the hydraulic system, is performed when the ignition is on for
engine start.
The following conditions must be satisfied in order to start or continue the test:
• Aircraft is on the ground and the associated engine FUEL switch is on.
• Hydraulic fluid quantity in each system reservoir is more than 2.5 gallons
(9.46 liters).
• System pressure sensors are operative.
• Auxiliary pumps remain off.
NOTE: If the auxiliary pump(s) are on when engine 3 is started, the HSC
turns them off in preparation for system 3 pump test.
When an ENG IGN switch is on, each left engine-driven pump is off and each
right pump is armed. After each engine is started and at idle rpm, a test of the
engine-driven pumps is automatically conducted.
The pumps are tested to ensure the following:
• The HSC can control the engine-driven pumps.
• The right engine-driven pump produces at least 2,800 psi.
• The right engine-driven pump ARM circuits are operating correctly.
Preflight Fail Alerts Test
If either preflight hydraulic system test fails, a HYD PRES TST FAIL or HYD
PUMP TST FAIL alert appears on the EAD. The HSC clears the alert when
manual mode is selected. Selecting manual clears the alert only, and does not fix
the cause.
Parked Configuration
When the aircraft is on the ground and all engine FUEL switches are OFF, the
HSC places the hydraulic system in the normal configuration.
Taxi Configuration
During taxi, the HSC:
• Does not turn the engine-driven pumps off.
• Places the hydraulic system in the normal configuration after each
engine-driven pump test is completed. Taxi is defined as aircraft on the
ground, any engine FUEL switch ON, and computed airspeed less than or
equal to 80 knots.
Takeoff/Land Configuration
Takeoff configuration is aircraft on the ground, speed more than 80 KTS, and any
engine FUEL switch on.
October 02, 2006
To Next Page
Loading...