CONVEX Tech Flashcards
What are the main components of the ADCS
Dual UARBs
Dedicated Links
RCM
Fault Tolerant Hardware
Fault Tolerant Software
What does the UARB network do in very simple terms
Allows the RCM to control all flight essential equipment on a dual network for redundancy.
What flow is information to essential components, one-way or two-way, and why
Two way as the fault tolerant components have their own processors to communicate complex data back to the RCM rather than just simple confirmation commands such as a switch being made. Some non-UARB components on other systems have a one-way flow of information as they are ‘dumb’ components without an individual processor and merely transmit a confirmation signal back that is binary in nature.
What components areSingle UARB Bus Components and only connected to a single UARB only
UARB A - 1 x Battery Junction Box, both PPDMs, 1 x Vote Processor
UARB B - 1 x Battery Junction Box, 1 x Vote Processor
What are Dedicated Links and give some examples
These are links for non-essential equipment directly to the RCM. This links compenents such as navigation sensors, attitude sensors, IFF, sensor payloads etc.
What functions does the RCM perform
Triplex Processing
Uplink command processing
Autopilot command generation
Downlink telemetry
Video data processing
What is an FCA and what does it do
Each Flight Computer Assembly (FCA) is a single board computer capable of independently controlling the aircraft and receiving sensor data. Each FCA outputs an independent stream of control commands and receives flight data from its own set of attitude and navigation sensors. A Cross-Channel Data Link (CCDL) between the FCAs allows them to share sensor data and datalink information.
What is meant by Triplex Processing
There are 3 x FCAs and 3 x GPS/INS, 3 x attitude sensors, 3 x pressure transducers. This allows triple redundancy and triple processing of the signals by each FCA which then uses mid-level voting to decide which signal to use.
What is Mid Level Voting
Mid-level voting is nothing more than selection of the middle
value. Each FCA then sends necessary sensor data to the other
FCAs. The sensor data from all sensors is voted on by all FCAs.
If only one sensor of the three has good quality, then that sensor’s
data is used. Otherwise, the three values are numerically
sorted, and the middle value is chosen. In either case, all FCAs
use the same sensor data.
What do the Vote Processors do
Each of the three FCAs produces two identical command datastreams. One command datastream from each FCA is sent to vote processor 1, and the other is sent to vote processor 2. The vote processors use the quality of the three command datastreams to select an FCA-In-Command. The command datastream from that FCA is sent out on the dual UARB assigned to that vote processor. UARB A is assigned to vote processor 1, and UARB B is assigned to vote processor 2.
How is the FCA-In-Command selected
The vote processors select the FCA-In-Command. Upon startup, they sample the command datastream from FCA 1. If good quality data is received from FCA 1, it is selected as the FCA-In-Command. After this point, the vote processors monitor the quality of data from each of the FCAs. Any time the quality of the datastream from the FCA-In-Command goes below that of any other FCA, the vote processors will select a new FCA-In-Command. They will select the FCA with the best quality datastream.
What are Fault Tolerant Components and what components are fault tolerant
Smart components that have their own microprocessors and can decide if the information being received from each UARB is high quality.
Aileron Servos
Flap Servos
Rudder Servo
Engine Control Servo
Landing gear retract servos
Brake servos
Engine Fuel Interface Unit (EFIU)
Avionics bay input/output (I/O) expander (nose lens heater, ice detector)
Wing I/O expanders (left & right with interface strobe power supplies)
Fuel heater controllers
Individual printed wiring assemblies in RCM
What does the fault tolerant software in the FCA do
This software determines which fault tolerant sensor to use based on mid-level voting.
Each FCA then sends the sensor data to the other FCAs. The sensor data from all sensors is mid-level voted on by all FCAs. If only one sensor of the three has good quality, then that sensor’s data is used. Otherwise, the three values are numerically sorted, and the middle value is chosen. If one sensor is reported faulty, mid-level voting still occurs.
If a faulty sensor fails to its upper or lower limit, the mid-level voting process will still take the faulty sensor’s value into account when determining the middle value. Should the faulty sensor fail to the middle value, its value will be selected, regardless of the health of the remaining sensors.
What happens to mid-level voting after the RCM resets
Mid-level voting is unavailable after an RCM reset. FCA 1 is in command by default after an RCM reset. The pilot must be aware of possible bad data in individual FCAs in order to avoid commanding a bad FCA.
What is an EGI and what does it do
Series of digitial and ring laser gyros that detect aircraft movement and gives that data to its assigned FCA.
Can an FCA only use the data from its correspnding EGI
No, it can use any EGI via the Cross-Channel Data Link (CCDL)
What is the primary and secondary communication pathways for each EGI to the FCA
Primary - 1553 Bus, Secondary - Hardwired RS-422
When using the CCDL, how does the RCM know which EGI to use
Each FCA uses mid-level voting every 20 milliseconds to decide
Once mid-level voting has taken place, what happens next to decide on which FCA is in command
Each FCA submits an identical data stream (via UARB A & B) to each vote processor, these then decide if the data is high quality and then assign an FCA in command.
What happens to the signal after the FCA in command has been decided
The signal from that FCA is sent out on UARB A and UARB B which is then processed by the appropriate remote terminal that uses atitude data i.e. stores, datalink etc.
What would “Nav sensor - positions do not match” or “Autopilot sensors do not match” mean
EGI fault of GPS degraded.
What are the main components of the Attitude, Air Data & Nav System
Everything but the Alpha & Beta sensors and Ku SATCOM are in groups of 3
3 x GPS antennae
3 x EGI
3 x FCA
3 x Airpseed transducer
3 x Altitude transducer
3 x Laser altimeter
3 x Pitots
3 x Static ports
What will happen in Ku if EGI 1 fails
Aircraft will lose link due to EGI 1 providing positional data to Ku SATCOM dish to align it accurately with its satellite.
If FCA 1 fails, why will the aircraft not lose link due to EGI 1 feeding into FCA 1
Data from EGI 1 will route to the other FCAs via the CCDL
How many pitot tubes & static ports does the aircraft have and what do they measure
3 pitots - 2 x left wing, 1 x right wing. They measure dynamic pressure
3 pairs of static ports - 3 on each side of the aircraft. they measure barometric pressure
What does the air that enters a pitot tube do
it is routed to a pressure transducer which calculates an electrical current from the pressure that is exerted. This is then used to give a corresponding airpseed
What does the air that enters the static ports do
it is routed to a pressure transducer which calculates an electrical current from the pressure that is exerted. This is then used to give corresponding altitude data
What prevents the pitots and static ports from become clogged with ice
Heaters
What altitude does the laser altimeter start to provide readouts on the HUD
100 ft AGL
What environmental factor could cause invalid Laser Altimeter readings
dust or moisture in the air
What is activated when the deice system is set to auto
Pitot and static heaters
What triggers the deice system to switch on in auto mode
Ice is dectected on the ice sensor (nose of aircraft) or OAT <10℃
What would you expect to find located on the Alpha Probe and what does each component do
Alpha Sensor - A potentiometer equipped windvane which provides AoA readings to the RCM and is used for Stall Protect
Beta Sensor - A potentiometer equipped windvane which is downlinked in telemetry and isn’t used by the RCM or Autopilot
Yaw String - Give a simple indication of yaw and is visible on the nose camera
OAT Sensor - Provides OAT information to the RCM in order to calcualte TAS, Density Altitude, and indirectly Lift Coefficient. The OAT is also used by the deice system
What is the tolerance of the OAT sensor
±3℃
What sensor should be used for Take-off and Landing Data (TOLD)
Engine Inlet Temperature on VIT 46
What altitude reference is used by default by the navigation system - Barometric or GPS
Barometric - GPS has to be selected by the pilot.
How many satellites are required for a 2D and 3D fix
2D - 3 satelittes, 3D - 4 satellites
What are P Codes in relation to GPS
Classified military precision GPS signals that are way more accurate than commerical GPS. These are loaded using a crypto key
What happens if there are no GPS signals received by the navigation system
The aircraft will use INS only
How accurate is INS
It will degrade by less than 0.8 nm every hour
What is the issue regarding LRE if 2 GPS sensors are reporting erroneous values
Mid-level voting may report an innacurate value which means accurate GDT location may not be achieved for LOS ops. Consider using visual references for aircraft position as HUD telemetry and tracker position may be innacurate
What could cause innacuracies with the navigation system during its startup process
Moving the aircraft as it needs to remain static to get the most accurate initial information
What is the normal “FCA# Stat” and “FCA# Err” codes that would show all FCAs are functioning correctly
FCA# Stat = F7
FCA# Err = 20
What is a Figure of Merit and what would you expect to see
It is a blended indication of the quality of the navigation and autopilot systems.
Code 1 = System is accurate to ≤25m
Code 9 = >5,000m
When are pitot and static heat powered on
Automatically commanded On when OAT is less than 10 °C OAT or any time ice is detected on the aircraft. Once ice is no longer detected and OAT exceeds 12 °C, the deice system commands the pitot and static heat to off or the previous pilot selected state.
What does the autopilot interect with on the aircraft
Flying controls, Engine, Attitude & Air Data System
What does the autopilot control when under autonomous flight
Navigation System, Transponder, Airborne Datalinks, MTS sensor control system, Video data system, SAR
What 2 modes ae there for Direct-To
Airspeed Hold or Airspeed and Altitude Hold
What happens to control sensitivity with Cruise Mode on and off
Control sensitivity is reduced by Crusie Mode
What is needed to enable Cruise Mode
- Any hold mode engaged
- > 110 KIAS
- Stall Protect enabled
When does Cruise Mode turn off
<100 KIAS
What Cruise Mode is on, what override function is activated
Roll limit override
What are the 3 hold modes
Heading, Airspeed & Altitude
What happens if the control stick is moved left or right in Heading hold mode
Nothing, no roll commands are sent to the aircraft
What route will Heading Hold turn the aircraft when a new heading is selected
It turns the shortest distance
What is the lowest commandable speed for Airspeed Hold mode
Airspedd Hold Active - It corresponds to CL = 1.25 with Airspeed Hold active
Altittude Preference Mode - 180 KIAS or 240 KTAS (whichever is slower)
Airspeed Preference Mode - 190 KIAS or 240KTASA (whichever is slower)
Altitude Hold On - airspeed is limited by Dive Priority Mode
How does the aircraft attiitude change to reach a commanded airspeed
There is no direct pitch control, however, the aircraft will respond in pitch to attempt to achieve the commanded airspeed
When airspeed hold is initially turned on what airspeed will the aircraft maintain
The current commanded airspeed. If a new airspeed is required then this will have to be set after Airspeed Hold is turned on.
How many degrees must pitch angle and pitch commanded be within before engaging airspeed hold?
±2 degrees
What is likely to happen with rapid throttle increases during climb-out with Airspeed Hold on
Aircraft will pitch up rapidly and approach stall conditions. If Aileron Tip Stall or Stall Protect is activated, reduce throttle input
What does the Airspeed Limit Override do
Prevents the pilot from setting and airspeed value lower than CL = 1.25 or CL = 1.05wen automatic flap schedule is not active or gear is down.
What happens if the pilot tries to set a commanded airspeed below CL = 1.15
The autopilot overrides the command and sets the lowest possible airspeed to remain within liits. “Airspeed Limit Override” is displayed on the pilot HUD
What does Altitude Hold Mode do
Maintains a commanded altitude
What are the 2 preference modes that can be utilised with Altitude Hold Mode
Altitude Preference Mode
Speed Preference Mode
What does Altitude Preference Mode do
The aircraft attempts to maintain airspeed for the commanded altitude by adjusting the throttle setting calculated by the closed loop power function
What does Speed Preference Mode do
The Aircraft attemts to maintain airspeed for the comanded altitude by adjusting pitch whilst maintaining the commanded throttle setting
In Airspeed Hold Mode without Altitide Hold engaged, how does the aircraft maintain altitude
the AP uses a speed-to-pitch relationship. A change in airspeed is compensated for by the AP which adjusts the pitch of the aircraft toachieve the commanded airspeed
In Airspeed Hold Mode with Altitide Hold engaged, how does the aircraft maintain altitude
Altitude Hold Mode engge means that either Altitude Preference or Speed Preference Mode will dictate how the aircraft achieve the selected airspeed
What are the rate of climb/descent ranges and the defaults
Climb - 100 to 3,000 fpm
Descent - 100 to 2,000 fpm
Default - 1,000 fpm
What happens to the throttle when Altitude Hold is engaged
It has no effect if it is moved
When does speed preference mode turn on
On - ≥CL 1.0
Off - ≤CL 0.9
What is the danger of Speed Preference Mode in a ROZ stack whilst MARSA
The aircraft will depart from its set altitude in order to maintain airspeed and result in height being lost rapidly and a potential airprox or collision
What will happen in Altitude Preference Mode in the same ROZ stack
If the aircraft is unable to maintain the set airspeed and altitude it will maintain the commanded altitude which will mean airspeed will reduce. The AP will maintain the highest aispeed possible whilst maintaining altitude
What is Best Climb Speed Override and what triggers it
The DFCS will override the comanded VSI if it exceeds the calculated rate of climb limits for the aircraft. The aircraft will replace the commanded VSI with the maximum calculated VSI.
What is Dive Priority Mode and when is it active
Automatically engaged during a descent in Altitude Preference Mode when within 5 kts of 190 KIAS or 240 KTAS. It prevents the aircraft from exceeding VNE. It automatically disengages when outside of dangerous parameters
How does the aircraft prevent VNE from being exceded in Dive Priority Mode
Engine is set to idle and airspeed is controlled by pitch
What is Speed Priority Override and how is it triggered
At higher airspeeds, with airspeed and altitude hold engaged, altitude preference mode will automatically be selected. In this flight mode, the aircraft controls altitude via the pitch command.
Altitude takes priority over airspeed and additional protection is needed to prevent stall.
If the indicated airspeed slows to a corresponding CL of 1.1 or stall speed plus nine knots, whichever is greater, the aircraft enters speed priority override mode,
What actions does the aircraft do when it enters Speed Priority Override
-Airspeed-to-pitch is enabled
-Airspeed command is set to the appropriate best climb speed - a speed that will achieve a CL of 1.0
-The warning: “Best Climb Speed Override” is sent to the GCS
When will the aircraft exit Speed Priority Mode
-Airspeed is not less than 2 KIAS below the best climb speed and the aircraft vertical speed is greater than the altitude-to-pitch controllers commanded vertical speed
-Aircraft is above the commanded altitude and indicated airspeed is above the minimum airspeed command (corresponding to CL = 1.25)
What is Aileron Tip Stall Override and how is it triggered
It automatically decambers the ailerons when Angle Of Attack (AoA) increases above +5° to prevent the wing tips from stalling. This feature is activated when cruise mode is off or stall protect is turned on. It is only deactivated if cruise mode is on and stall protect is off.
Why is Aileron Tip Stall Override required
It automatically decambers the ailerons when Angle Of Attack (AoA) increases above +5° to prevent the wing tips from stalling. This feature is activated when cruise mode is off or stall protect is turned on. It is only deactivated if cruise mode is on and stall protect is off. This feature deflects the ailerons down by an equal amount on each wing (if wings are level).
What AOA is required before ailerons will deflect
ᐩ5° to ᐩ9°
How is Aileron Tip Stall Override dealt with in relation to pilot inputs
The Aileron Tip Speed Override deflections are added to any pilot inputs thus decambering the wings more rather than less.
What is the maximum deflection possible
8° at AOA readings above +9°
What is Stall Protect and when is it enabled
Prevents stall by limiting aircraft AoA. Stall protect is turned on and off by the pilot, but only takes effect at speeds below 120 KIAS. Stall protect is automatically disabled at speeds 120 KIAS or greater, and automatically turns on below 120 KIAS when autopilot is engaged. Stall protect will not turn on, if the pilot has it commanded Off and with no autopilot engaged.
How does Stall Protect prevent the aircraft from stalling
The aircraft deflects the ruddervators down when AOA exceeds limits
What AOA range is required for Stall Protect to activate
Engages when +7° AOA and disengages when AOA is <3° AOA
What is automatically turned on with Stall Protect
Cruise Mode
What is the problem with the stall speed displayed on the HUD when Cruise Mode is on
When in cruise mode the stall speed indication on the HUD represents a CL=1.5 regardless of flaps settings, which is approximately the stall speed with flaps at 30°. Reference TO 1Q-9(M)A-1-1 for accurate stall speed computation.
What is Roll Limit Override
The roll limit override feature uses CLVmin limits to limit command roll to maintain a safety margin between the aircraft’s indicated airspeed and its stall speed due to roll angle.
What is roll limited to during autopilot controlled turns
Roll is limited to 30 degrees during autopilot controlled turns.
What CL is used to limit roll
Auto flap - CL = 1.25
Manual flap - CL = 1.05
When is Roll Limit Override enabled
When any of the following are true:
-Heading hold is on
-Stall protection is on
-Airspeed hold is on
-C-Band LOS is lost link
-In a SATCOM link type
What happens if the pilot commands a roll angle that is unsafe
The AP automatically limits the aircraft roll to a safe limit and displays “Roll Limit Override”