Hydraulics Main Flashcards
What do the main hyd pumps provide hyd pressure to
flight controls, apu, rescue hoist
what does the utility hyd pump provide hyd px to
dome
hyd system components
3 identical hyd pumps, 2 transfer modules, one utility module, 3 dual stage primary servos, 2 tail rotor servos, pilot assist servo assembly, apu accumulator, and the rescue hoist
general pressure of the hyd system
3000 psi
what component of hyd system is at a lower px
pitch and roll trim actuators in the pilot assist servo assembly which are at 1000 psi
what kind of distribution system
dual isolation distribution system
when will we get a hyd warning
when the hyd system is severely degraded as a result of several compound malfunctions in #1/#2 and back up sys
what does the #1 pump power
1 pri servo and 1st stage of tail rotor servo
what are the components of the #1 hyd sys
1 hyd pump, #1 xfer module, 1st stage pri servo, 1st stage tail rotor servo
parts of the #1 hyd pump
px relief valve, bleed valve, px filter, return filter, automatic low level sensing switch
how many PDIs per pump
2
Of the 2 filters in the hydraulic pumps, which is bypassable
the return filter, the pressure filter will not be bypassed and allow bad fluid in
what causes the #1 RSVR low caution
closing of the auto low level sensing switch
purpose of the #1 transfer module
passes fluid from the #1 pump to the first stage pri servo and 1st stage tail servo, and in the event of loss of pressure of the #1 pump routes fluid from the back up pump
1 transfer module components
transfer/shutoff valve, pressure switch, first stage pri shutoff valve, first stage tail rotor shut off valve
What causes the #1 hyd pump caution
activation of the pressure switch in the #1 xfer module which also signals the LDI
what does the #2 hyd system power
second stage primary servos, pilot assist servo assembly
2 hyd sys components
2 hyd pump and xfer module, second stage pri servos, pilot assist servos
where is the #2 pri servo shutoff valve
2 xfer module
can we directly actuate the pilot assist servo shut off valve?
Kind of, not fully secured with just one button
what does pressing the sas/boost push button secure
hyd pressure to the boost servos and SAS actuators
what causes a pri servo press caution
at least one of the 3 pressure switches on that stage sense low px
what does the back up hyd sys do
powers #1 and #2 hyd sys before rotor spin up, powers rescue hoist system, and recharges the accumulator, and provides redundancy
SAR concern if the b/u pump is supplying power to 2nd stage T/r
priority valve may secure hyd power to the rescue hoist
back up hyd sys components
back up hyd pump and utility module
caution about b/u hyd pump cb?
if the b/u hyd pump cb is out and a condition exists that would cause it to turn on upon being reset, you must either secure ac power or remove that condition before resetting or it may damage the current limiters and cause you to lose all loads and the #1 ac pri bus
difference between b/u hyd pump and other pumps
powered by ac motor not engines/transmission
b/u hyd pump contains what to ease start up for electric motor
internal depressurizing valve
time frames associated with b/u pump energization
4 seconds on APU or ext power
.5 sec on main gen
Weight on wheels B/U pump switch
off, on, auto
off - pump will stay off
on - if #1 and 2 are operating normal, it circulates fluid and maintains px in apu and rescue hoist
auto - holds px in #1/2 systems (including second stage tail servo) if LDI requires
Weight off wheel B/U pump switch
off, on, auto
off/auto - auto maintains power in the #1/2 systems if required by LDI - will also hold px second stage if tail servo sw placed in backup
on - if other pumps operating normally, circulates flyid and maintains px in apu accum and rescue hoist
how long minimum will the b/u pump operate if apu accum low
90 sec
180 if winterization kit is installed
What will automatically turn on the b/u pump
1 HYD pump (aka loss of px)
#2 HYD pump (aka loss of px)
#1 RSVR low
#1 Tail RTR servo (aka loss of px)
what does the utility module do
routes fluid to #1/2 xfer modules, second stage tail servo, rescue hoist and apu accum. it also contains a px switch that indicates when the pump is on
what is the purpose of the priority valve between the utility module and rescue hoist
restricts hyd fluid to rescue hoist if px goes below a prescribed level
what is the purpose of the velocity fuse in the utility module
secures fluid flow to the apu accumulator if flow rate goes past limit
first reaction of LDI if #1 rsvr low
assumes leak is in 1st stage tail rotor servo lines and secures the 1st stage tail servo
first reaction of LDI if #2 rsvr low
assumes leak is in pilot assist servo assembly and secures hyd pressure to the assembly
if a leak progresses from rsvr low to hyd pump caution, what does LDI do
reopens the valve it shutoff and relies on pilot to secure the affected pri servo
5 requirements for a hyd leak test
AC power
B/U hyd pump switch auto
All rsvr’s full
Weight on wheels
rotors engaged
it tests all hyd circuitry except for xfer shuttle valve operation
10 lights indicating successful hyd leak test
1 rsvr low
#2 rsvr low
buck up rsvr low
Back up pump on
SAS
boost servo off
afcs degraded
#1 tail rtr servo
#2 tail rtr servo on
master caution
what doubles as the rotor brake rsvr?
coffee can
components of utility hyd sys
hyd pump, rsvr manifold, main xmsn oil cooler, distribution sys
px of utility hyd sys when off/on
1000/3000psi
