AFCS Flashcards
What does SAS do?
What is the difference between SAS 1 and 2?
What percent control do they have?
Senses acceleration and applies control to reduce the rate.
SAS 1 is Analog, SAS 2 is Digital. They are identical except for the hover aug/ gust alleviation and alt hold/ hover coupler provided by SAS 2.
They have 10% authority With each providing 5%.
SAS 2 commands the collective inner-loop actuator by operating with ___________
RADALT, BARALT, APP/HVR and DEPART MODES ENGAGED.
Which SAS must be manually disengaged by the pilot if it has failed?
SAS 1
SAS 2 will be turned off by the AFCC.
Which trim servos are electric?
Hydraulic?
Yaw, collective
Pitch, roll
Trim is limited in movement by _________
10% percent per second
To disengage yaw trim above 50 kias the pilot must _________
Below 50 kias?
Push the cyclic button and the trim micro switches
Just the pedal micro switches
Auto pilot does what?
Maintains pitch and roll attitude, airspeed, heading during cruise
And
Provides a coordinated turn above 50 kias.
Attitude hold is engaged below _______, and using the 4-way trim switch will adjust pitch attitude at a rate of _________.
50 kias
5* per second
Airspeed hold is engaged ___________. The 4-way trim switch will adjust the airspeed by ___________. The lateral trim roll rate is _________. It resets to __________ when you ___________.
Above 50 KIAS and AOB less than 30*
6 KIAS per second
6* per second
Wings level
Accelerate through 50 kias
Heading hold is slewed at ____ below 50 kias and _______ above 50 kias.
3* per second
1* per click or 1* per second
Heading hold is re-engaged when what 2 conditions are met?
Roll attitude is within 2* of wings level
Yaw rate is less than 2* per second
Disengaged by WOW switch.
Altitude hold: The AFCC commands both the ____ and the ____ to maintain the reference altitude.
It will stop increasing power if torque hits _______ above 80 kias or ________ below 80 kias.
Collective SAS actuator and collective trim actuator
106%
120%
Altitude that RADALT will work?
0 to 5000ft AGL.
RADALT and BAR ALT require what push buttons to be engaged?
SAS 2, TRIM, and AUTOPILOT
RADALT climb and descent rates?
1000 ft per minute
200 ft per minute
What does hover augmentation/gust alleviation do?
Improves aircraft stability at low airspeeds by using attitude retention, longitudinal acceleration, and lateral acceleration to eliminate drift.
Turn coordination is provided ______. It will engage when _________ and any of what 3 conditions exist?
Above 50 KIAS
Roll attitude is greater than 1*
And either:
1) lateral cyclic displacement is greater than 3%
2) Cyclic TRIM REL is pressed
3) roll attitude is more than 2.5* using 4-way trim
The purpose of Maneuvering stability is to __________. It is provided by _________ between _______.
The ___________ push button must be engaged for it to function.
Increase pilot effort to maintain pitch rate at greater than 30* AOB
Pushing the cyclic forward by 1% for every 1.5* AOB. Between 30* and 75* AOB.
Autopilot
Automatic approach assumes _______ when engaged and again at ________.
Wings level
80 KIAS
The 4-way trim switch changes the deceleration rate by ________ during the automatic approach.
It will reset the deceleration profile at _____________. Pressing the ________ will reset the profile.
+- 1kt per second, 2 seconds for a full knot.
40KGS
TRIM REL
Automatic approach profile numbers?
ON (above 40KGS and below 40KGS)
Below-
Above-
Above 40: 2.5kt/sec 215 ft/min
Below 40: 1.5kt/sec 130 ft/min
Below profile: 2.5 kt/sec w/RADALT hold
Above profile: 360 ft/min w/airspeed hold
What is the Warning associated with an automatic approach?
If auto approach is turned on while in a trimmed turn it will spiral downward past the selected altitude and crash.
Hover coupler speeds can be varied by ________ with the 4-way trim switch.
Hover coupler will automatically engage after an automatic approach when __________ and manually when within ________
+- 10
Within 2 ft and 1KGS
Or
5KGS
The hover coupler will stop increasing the _______ at ________.
Collective torque
116%
During couple hover if winds are greater than 50KIAS and the cyclic trim is depressed the ____________
Heading hold will be disabled. This could cause rapid deviation from the desired helicopter heading.
Automatic depart, if not interrupted, will reach _____ and ______.
150ft and 120kias
Automatic depart assumes __________ at _______ if bank angle is ________.
If bank angle is greater than ____.
Automatic departure will limit power at __________.
Wings level attitude, 50KIAS
Less than 5*
5* it will maintain a coordinated turn.
106 and 120% dependent on airspeed.
Automatic departure profile?
240ft/min climb
3kt/sec below 85 kts
1kt/sec above 100 kts
Crew hover control authority?
+- 5 KGS
Cable angle is decoupled from the AFCS for ____ when dome raising/lowering is stopped or started in the water.
9 seconds
Scale on the cable angle display is _________. The rings are at _____ and ______.
2 degrees per tick
- 25 degrees
- 5 degrees
CABLE ANGLE AT LIMIT caution appears when ___.
cable angle has exceeded 7.5 degrees total deflection.
The helicopter will default to HVR mode at _________ during cable angle hover.
If either axis is failed it must be _________.
What should you not continue if both axis are failed?
27+- 12 ft water depth.
Manually controlled
Dipping operations.
What is required for Cable Angle Hover Mode?
KGS of +-5
Altitude hold w/in 10 ft.
Dome wet indication.
The ______ are inoperative when CABLE ANGLE HOVER is engaged.
LONG VEL and LAT VEL potentiometers.
Cable angle takes ______ to come up with a solution.
25 seconds. Do not make inputs during this time.
Cable angle hover will not _________ with ____________ engaged.
Disengage
Cable angle override on. (Must be manually disengaged)
To conduct AFCS preflight checks you need:
BREWS
Both EGIs attitudes valid Rotor brake ON Engine torque below 10% WOW SAS 1 ON (AFCC must be on for at least 20seconds)
If one of the SAS channels fail, what operable control authority is the operable channel limited to?
+-5 percent authority, but it operates at twice the normal gain to compensate for the failed SAS channel
When does the SAS caution appear?
Whenever SAS 1 and SAS 2 lose electrical power or when hyd pressure is lost to the actuators.
Is Trim an outer-loop functions, or inner-loop?
Outer-loop
Cable angle is used to keep the cable ____ to the water.
Perpendicular
What does the SUBM OVRD button do?
Provides override capability of the 27+-12 ft submerge requirement to engage cable angle hover mode. (in case you’re dipping in shallow water or don’t have the dome wet indication.)
How do you initiate the automatic preflight check?
by pressing the SAS 1 pushbutton. Takes approx 10 seconds to complete.
3 major subsystems
SAS
AFCC
Stab
19 Functions of the AFCS
6 hover, 5 hold, MASTBSTD
- Maneuvering stability
- Automatic preflight checks
- Stability augmentations (pitch, roll, yaw)
- Turn coordination
- Blade Fold Assist
- Stab Control
- Trim (pitch, roll, yaw)
- Diagnostics
- Crew hover
- Cable angle hover
- Auto approach
- Auto depart
- Hover coupler
- Hover augmentation/gust alleviation (pitch and roll)
- BAR Alt
- RAD Alt
- Heading hold
- Attitude hold (pitch and roll)
- Airspeed hold
2 types of AFCC control
- Inner loop (SAS)
2. Outer loop (autopilot)
Inner loop is
fast in response, limited in authority, and does not move the flight controls
Outer loop provides
Long term input by moving flight controls through their full range of travel (100% authority) at a limited rate of 10% a second
ATT caution cube indicates loss of pitch or roll attitude or
3 deg miscompare between EGIs
AFCC uses the ___ to choose between the ___ for the best source of power
Voltage sensor relay
AC primary buses
4 Inputs to the Stab
Collective Position
Lateral Acceleartion
Airspeed
Pitch Rate
How is the stab positioned? What buses power its movement?
2 electrical jackscrews acting in series
Each jackscrew provides 1/2 the input
DC Essential & No 1 DC Primary
Stab movement if it fails full down/up?
35 degrees if fails full down, 30 if full up
Primary purpose of the stabilator
To eliminate undesirable nose up attitudes caused by rotor downwash on the horizontal stab during transition to a hover and low speed flight
When is the TEST pushbutton for the stab operable?
Below 50 KIAS
Range of motion for the stab
42* trailing edge down for hover/low speed flight (below 30 KIAS) to 10* trailing edge up for cruise and maneuvering flight
AFCS is what type of system?
Electrohydromechanical
