Flight Controls Flashcards
Flight controls
Consists of
- dual control inputs (pilot and copilot): collective, cyclic, pedals
- hydraulically boosted mechanical control system with dual primary servos. Without the primary servos the pilot would not be able to move the main rotor system.
- flight controls use a series of push-pull rods, bell-cranks, boost servos and SAS servos, mechanical mixing, and primary servos that transmit control movements from cockpit to main rotor. Tail-rotor uses cables, pulleys, fwd and aft quadrants and tail rotor servos.
- flight control system can be controlled by the Flight Director thru fps/Trim features
- SAS makes dynamic adjustments to the rotor system to help compensate for wind, turbulence, and other minor disturbances
- flight control components can be associated with their location;
1) Cockpit - forward - pilot and copilot stations
2) Mid aircraft - cabin and cabin top-flight control hydraulic deck
3) Tail section - tail boom and vertical pylon
Cyclic
Go around button - wings level, 70kts, 750fpm rate of climb
Trim Beeper Z-axis plunge - above 60kts, rolls wing level. <80kts, accelerates to 80kts. 80-120kts, holds speed, >120kts slows to 120kts. Below 60kts, hover options
Trim Rel - pressed to disengage or realease cyclic trim
RMT SBY - places the flight director into a standby mode
C/F DISP - pressing down or up ejects chaff-flare cartridges
Cargo Rel - initiates the normal ELECTRICAL release of the cargo hook external load
WPN REL - initiates launching of weapons, including volcano if installed
VOX-CAUT - push button acknowledges the master caution and any audio warnings
ICS/Radio - pull-to-talk switch is a two-detent trigger control; first activates ICS, second activates external radio
SLEW UP - a cyclic mounted stabilator slew-up switch provides the pilots with a pull to slew-up function that causes the stabilator to move trailing edge up
Collective
Copilot collective stows for ease of entry/exit (must be extended and locked for flight)
HOOK EMER REL - activates emergency release of external cargo by activating a battery operated explosive charge
HUD - button controls multiple operations of the heads-up display; PG UP/DOWN scrolls, BRT/DIM adjusts display light intensity, and DCLT Declutters the selected display
SEARCH LIGHT CONTROL PUSH ON/OFF - pushing the center of the control activates or deactivates the searchlight. Activation in any of four directions moves search light in that direction
TRIM REL - releases the current collective trim reference position and gradient force and re-engages new position
LDG LT PUSH ON/OFF-EXT/RETR - duh
CRSR SLEW PUSH-SELECT - selects and controls the movement and direction of the cursor on the MFD screens
RAD SEL - allows the pilot to cycle through the selected radios presets (and enhanced features)
AFCS TRIM BUTTON - (Collective Trim Beeper) - adjusts collective up or down and TRIM L or TRIM R adjusts the aircraft heading reference (yaw trim) below 50kts. Above 50kts, TRIM L or TRIM R will place the aircraft in a standard rate turn (roll trim)
Pedals
The pedals provide an input to the tail rotor servo that results in YAW directional control
Pedals have switches on them that when pressed, will disengage yaw trim
Pedal position is adjustable with the PED ADJ T-handle which can be moved forward or aft
Tow portion of each pedal is for individual brake application
At airspeeds less than 50kts, pilot may change heading reference by pressing the pedal (and pedal switch), position the helo and then release
Helo Above 50kts should hold heading indicated (zero yaw rate for two seconds) at the time the pedal switches are released +/- 2 degrees… only way to change the yaw setting is to press pedal and hit trim release
Trim (SAS)
Trim provides collective, cyclic, and pedal flight control position reference and control gradient
Trim is turned on by pressing the TRIM button on the STABILATOR CONTROL/AUTO FLT CONTROL panel
Pitch actuator operates on 1000psi due to long axis and stabilator (drag)
Boost servos for collective, pitch, yaw, boost servos are turned on (pressurized) by SAS/BOOST button (mechanical hard-over/boost servo hard-over will increase cyclic control forces 20lbs in the pitch axis. These forces can be reduced by turning SAS off)
Mechanical Mixing Unit (MMU)
Is designed to mechanically reduce inherent control coupling by compensating for the effect of one control input on another
If a cable snaps and caution comes on, ONLY CHECK BY ADDING OR DECREASING COLLECTIVE. If you add pedal and both cables snapped, you can cause a dive because MMU compensates for the tail rotor lift!!!
***FCC will start removing pedal inputs from the MMU from 40kts to 100kts, because the MMU is rigged for hover primarily. Important to know for the future!!
***Collective to Pitch, collective to roll, collective to yaw, yaw to pitch by MMU
Primary servos
It is not possible to fly this aircraft without hydraulics
There are 3 hydraulic systems - #1, #2, and the Backup #3
Lateral is left
Aft is center
Forward is right
Dual stage servos that provide the combined flight control inputs to the swashplate, which in turn provides the pilot the ability to move the entire main rotor assembly.
Backup pump is electrically operated, and pump #1 and #2 are operated when the rotors are turning. These pumps provide the servos their pressure. All three of the pumps are identical and swap-able.
Electrical interlocks prevent both flight control servos stages from being turned off simultaneously.
AFCS Aircraft Flight Control System
Control panel on lower console
Failure reset buttons will show nothing unless a failure occurs
The stabilator control section contains the MAN SLEW switch, a TEST button, and an AUTO CONTROL RESET
The AFCS contains SAS 1, SAS 2, Trim, FPS and SAS/BOOST, ON/OFF, as well as CPTR 1 and CPTR 2 failure resets.
MISC Panel
Mounted on the lower center console
Tail servo - if BACKUP is selected OR servo 1 failed, illuminates the SFO 1 FAIL caution, T/R SERVO 2 ON advisory, and MASTER CAUTION. Backup pump should turn on and advisory appear:
BACKUP PUMP TURNS ON AUTOMAGICALLY WHEN (switch in auto) and will always turn to auto after liftoff (WOW switch)
1) Hydro pump 1
2) Reservoir 1 low
3) Tail servo one fail
4) Hydro pump 2 on
5) APU accumulator low (Backup will always turn, no matter the switch position or WOW)
HYD leak test - allows testing of the Leak Detection Isolation (LDI) feature
**SERVO OFF SWITCH - primary rotor servo switch; middle keeps both on, up turns 1st Stage off, down turns 2nd Stage off…. 6 tubes, 2 stages so 3 tubes per side, you can only turn off a stage, not an individual servo… because all three servos work together for collective control! Switch to the other stage brooooooosky
SAS1 and SAS2 are completely independent from each other, but share stabilator data
FCC2 is plugged in for tail/yaw control and controls trim, and FCC1 is not
Know
1 and #2 hydraulic pumps are mounted to the ACCESSORY MODULES
Hyd pump 1
Hyd pump 2
Backup pump
Leak - RSVR 1 or 2 or BU
Pump failure - HYD PUMP 1 or 2 FAIL
Jam - PRI SERVO 1 or 2 FAIL; Boost SERVO OFF; TR SERVO 1 FAIL
Backup Pump operation auto:
1) #1 HYD PUMP 1 FAIL
2) #1 pump RSVR 1 LOW
3) #1 pump TR SERVO 1 FAIL
4) #2 HYD PUMP 2 FAIL
5) APU ACUM LOW
Hydraulic Logic
1) LDI
2) Turn on BU PUMP
3) Possible Give/Take Back
3 boost servos are turned on and off by the SAS/Boost button
3 anti-jam redundancies per servo
Study the logic trees for the hyd pumps
Servo switch is a lift-gate switch, only you can turn it off
Tail rotor servo can be switched by you or A/C
Electrical interlock - system will not allow you to turn off the good servo stage… PREVENTS BOTH SIDES FROM TURNING OFF SIMULTANEOUSLY
Reservoir low means there is a leak
Depressurization valve on the backup pump allows it to be used every time you run the aircraft (since it is electrically driven)
If RSVR 1 comes on, and right after the BACKUP RSVR LOW comes on, the Primary servo stage 1 has a leak, you MUST switch over to Primary 2 (and vice versa)
Backup pump on and tail-rotor 2 servo on are correct pilot action indications
Velocity fuse 1.5GPM
GO OVER THE CHECK-ON LEARNINGS
Depressurization valve on the backup hyd pump negates the possibility of popping circuit breakers and allows the backup pump to be used every time we fly
LDI - turns off the tail rotor servo on system #1 and pilots assist on system 2 if a RSVR light comes on for either.
PUMP = mechanical malfunction RSVR = leak
***RSVR 2 LOW = light comes on, LDI will shut iff Pilot Assist.
IDENTIFY BEFORE AND AFTER PILOT ACTION!!! TC’s logic tree
You do not have control of the valves that the LDI controls to turn off pilot assist (Pump 2), but you DO have control of the tail hydraulic valve (Pump 1) by means of the backup switch
Transfer valve in the transfer module makes sure the backup pump does not transfer backup pump pressure to a leaking/empty pump.
Yaw boost servo (1.5in of play)
SAS has 5% input authority per system (10% total if both used)
Pitch boost can stop SAS feedback from reaching the cockpit. If 20lb of pressure is needed to pitch the cyclic, turn off SAS/BOOST.
YAW Trim (hard-over) takes 80kb of force to push through, YAW boost (hard-over) takes 250lb to push through
Collective boost (hard-over) takes 150lb to overcome. Collective Trim (hard-over) is 22lb
Inputs to the HMU - power control levers, load demand system through collective, and electrical input (DEC - torque motor)
**DEC has control of hot start prevention (900C before idle speed, will close the ODV), NP overspeed protection (uses ODV valve to flame engine out), torque matching/load sharing, TGT limiting, NP governing. If the DEC dies, you can use the power control levers to control NP Governing, Load Sharing, and TGT limiting. If it dies, the engine will spool to it’s maximum power regardless of TGT limiting so you need control it! You will have no idea what your torque is if the DEC dies
- Must wait 25 seconds before starting the engine again after a hot start occurs
- We want to shut the engine off if the temp reaches 851*F before idle speed is reached
