AFCS Limits Flashcards
What are the diagnostic cube functions?
-alert pilot to AFCS malfunctions/failures and to what part of AFCS
- acknowledge = stop flashing = red circle button
- clear = clear failure/warning = push cube in
-pushing cube is an alternate method to turn on SAS 2
All hover limits are what type of airspeed?
Groundspeed
4-way trim swictch: limits
-attitude (<50 KIAS) = pitch = 5°/second
- airspeed (>50 KIAS & <30°AOB) =
- ————————pitch= 6 KIAS/second
- ——————–‐—roll = 6°/second
Heading hold: trim rocker limits
- A/S <50 KIAS = 3°/second
- A/S >50 KIAS = 1°/second
Heading hold re-engages after what?
When BOTH occur together for 2 seconds:
- wings within 2° of level
- yaw rate <2°/second
What happens when you pass through 50 KIAS on auto departure
Wings automatically are leveled
What is required for heading hold to be activated?
Weight OFF wheels and AUTO PLT on
How do you change your heading hold?
- A/S < 50 KIAS = pedal microswitches
- A/S > 50 KIAS = pedal microswitches AND cyclic trim release
What are the rate changes when you use the heading trim rocker?
- A/S <50 KIAS = 3°/second
- A/S > 50 KIAS = 1°/single click OR 1°/second held
When does BARALT hold work?
Any airspeed, any altitude with SAS 2, TRIM, AUTO, and BARALT on
What is the short term sensor for thr BARALT?
Integrated vertical accelerometer
What is the long term sensor for the BARALT?
rate sensor
When does RADALT hold work?
0-5000’ AGL and any airspeed
How is the RADALT altitude changed at 200’ AGL or below?
Purple putch potentiometer
What is the recommended entry profile into an auto approach to hover?
150’/60 KIAS (ICW)
Auto approach to hover entry profiles
- A/S > 40 KIAS ——> 215 fpm descent & 2.5kts/sec deceleration
- A/S < 40 KIAS ——-> 130 fpm descent & 1.5kts/sec
- ABOVE PROFILE –> 360 fpm descent
- BELOW PROFILE—> RADALT hold and 2.5kts/sec. decel. until reaching profile
How do you change your accelerstion/deceleration rate during an auto approach to hover? How do you return to factory settings/parameters?
Use the 4-way trim switch to accel or decxel at 1kts/sec. To go back to standard rates, hit the cyclic release button
What’s a warning to consider when executing an auto approach to hover?
System assumes you are straight and level. If you have a turn trimmed in, you will death spiral. Requires pilot intervention to stop.
When does hover coupler mode engage at the end of an auto approach?
-automatically when within 1 kt of pre set airspeed
Or
-manually when within 5 kts
Or
RADALT hold engages within 2ft of thr altitude set on the potentiometer
What are climb and descent limits in hover coupler mode?
Cannot exceed >1000fpm climb or >200fpm descent
What does the AFCC limit your torque to in hover coupler mode?
116%Q
How can you manipulate speed and direction in a coupled hover?
4-way speed trim gives pilots +/- 10 kts in any direction
Why do you need to pay attention to airspeed while moving in hover coupler mode?
You might exceed 50 KIAS because of wind and be kicked over to airspeed hold
What profile does an auto departure take you to?
150’ AGL and 120 KIAS (aka transit airspeed between dip to dips)
Rates of departure during an auto departure
-initially: climb at 240 fpm and accelerate rate at 3kts/second
- @ 85-100kts = airspeed fade range
- @ 50’ AGL = aircraft auto sets wings level if AOB<5°
-then: when greater than 100kts, acceleration slows to 1kt/second
-finish: 150’AGL/120KIAS UNLESS:
Cyclic trim release pushed = stops speed accel
Collective trim release pushed = stops climb
What 4 things program the stabilator?
CLAP
C- collective position
L- lateral acceleration
A- airspeed
P- pitch rates
Stabilator manual slew deegree/airspeed emergency limits
0° = 150 KIAS 10° = 100 KIAS 20° = 80 KIAS 30° = 60 KIAS 40° = 45 KIAS
What are your slewing limits when the stab fails?
- full up = 30° slewing capability
- full down = 35° slewing capability
What does gust alleviation do?
SAS takes input from winds and alleviates some control pressures and improves stability
What is maneuvering stability
It is artificial G-loading.
Meaning the cyclic is displaced forward during high AOB turns
What is the maneuvering stability rates?
1% forward cyclic for every 1.5° AOB increase between 30-75°AOB
At 75°AOB it will be 30% fwd cyclic
What kind of trim controls are there?
- cyclic
- Collective
- pedals
How many trim servos are there?
4
- 2 had boosted at 1000psi (pitch and roll)
- 2 electric servos (Collective and yaw)
What is SAS?
Stability augmentation system that senses rate acceleration in P/R/Y and inputs rate dampening for improved stability
SAS 1 vs SAS 2
SAS 1 is analog and is P/R/Y only
SAS 2 is digital and has hover augmentatioj, gust alleviation, ALT hold and hover coupler, turn coordination, and roll ATT hold
Inner loop vs outer loop AFCC control
Inner loop = SAS = fast rate response = limited to 10% authority = no cockpit control mvmt
Outer loop = autopilot = limited to 10% per second for rate response = full 100% authority = can move cockpit controls
Auto prefligjt check requires what
Initiate by pushing SAS 1 after WERDS is met:
W- wow E- engine Q < 10% R- rotor brake on D- dual EGI valid S- SAS 1 on (after AFCC on for at leastn20 secs)
Blade fold assist does what?
AFCC commands all trim actuators to out flight controls in correct position to facilitate blade fold,
then pitch-lock actuators engage,
then blade fold commences
How long is the auto preflight check and what does it test?
It takes about 10 seconds. It tests the rate gyros are set, magnitude and polarity of their response is checked, and SAS 1analog is compared to SAS 2 digital readings
What happens if a SAS fail?
If one fails, AFCS DEGRADED caution appears and SAS on diag cube, the other compensates by increasing twice the gain (still only 5% authority though)
If SAS 1 fails, pilot must manually disengage via AFCS panel
If SAS 2 fails, the AFCC automatically disengages affected axis
Where do SAS actuators get their px from?
Hyd px from PAS module via SAS shutoff valve
What is cable angle hover?
It is a hover used for dipping operations, it keeps the helicopter, cable, and sonar all in line/perpendicular
Limits while towing a sonar array?
What is the definition of towing?
Folded = 8KGS Unfolded = 4 KGS
Towing is when the cable contacts the funnel
How is cable angle engaged?
How is it disengaged?
Engaged by pressing CABLE ANGLE on SONAR CABLE ANGLE control panel
Automatically disengaged when dome is reeled up through 15-39ft water depth
OR
When pilot pushes CABLE ANGLE again
What conditions are required for cable angle engagement?
- in coupled hover
- +/-5 KGS
- ALT hold within 10 ft of selected altitude
- dome wet indication
What does the ALFS cable angle sensor measure?
They measure the angular displacement of the cable from the center of the funnel relative to aircraft orientation
While dome is submerged, it maintains perpendicular angle between cable and water (dead center on display)
Cable angle display reference
Each tick = 2°
Inner ring = 4.25°
Outter ring = 8.5°
POCL = paid out cable length in ft = bottom left corner
Dipping depth = bottom right corner
TTR = time to reel
Ft in AGL = top right corner
Warning/caution with cable angle dipping ops
CABLE ANGLE AT LIMIT alert
If the 8.5° outer ring is reached while the dome is leaving the water, there is a SIGNIFICANTLY INCREASED RISK of the dome sticking the aircraft including the aircraft rotor which may result in aircrewman injury and/or death.
If the 4.25° inner ring is exceeded as the dome ks leaving the water during raise operations, there an INCREASED RISK of the sonar dome sticking thr aircraft which may result in equipment damage
CABLE ANGLE LIMIT = potential cable damage and/or cable has exceeded 7.5°
UTILITY HYD PUMP
UTILITY HYD PUMP HOT
UTILITY HYD RSVR LOW
UTILITY HYD PUMP CAUTION
Stop dome
