FCS (flight control surfaces)

FCS

Flight control system

MAMS

Mass and store management function

Una delle capacità dell FCS

FCC

Flight control computer

IMFP

Integrated multifunction display

Provide air data sensing

TAT

Total air temperature probe

Provide air temperature data

PIT

Pilot input transducers

Provides FCS/pilot interface

ATU

Aircraft transducers unit

provide aircraft inertial data

MSU

Magnetic strap-down unit

Providing magnetic field component

FCS components

4 FCC

4 IMFP

1 TAT

3 PIT

4 ATU

1 MSU

FCC provides the following functions

• pilot/cockpit control and aircraft state sensor interface processing

• Input validity monitoring and cross channel monitoring

• Actuator servo loop control and monitoring

• BIT capability

• Warning and caution logic implementation

FCC IS POWERED…

each FCC is powered independently by dual redundant 28V DC power from essential and battery busses (left/left or right/right)

CCDLs

Cross channel data links

Provide information transfer between FCC channels

Each FCC includes…

Single ARINC 429 and RS422 interface

Dual redundant MIL STD 1553B terminals to interface with FCS and avionics bus

AHRS

Attitude and heading reference system

Provides the 4 FCC with heading and inertial info as inputs for the control laws

AHRS consists…

4 ATU (aircraft transducer units) connected to FCC via Arinc429 bus

1 magnetic strap down unit, providing magnetic field data to the ATU via RS485 bus

ATU not aligned

ATU alignment starts when system supplied with power

With aircraft stationary on ground ATU data are cross checked with IN/GPS. If this operation fail pilot can force ATU alignment but system takes 30s to start after GC/FAST press.

If before INGPS alignment or 30s the aircraft starts moving “monitor not active” message

How does GHD (get home display) receive info?

FCC transmit ATU info via MIL-STD 1553B bus to the GHD independently from the info that go to the MFD

If EGIR is unavailable

FCC provide attitude data from ATU to avionic/navigation equipment

ATU malfunctions are displayed…

MFD - IN/GPS format

AFU

Artificial feel units

Connected to the mechanical link to provide pilot feeling of pitch roll and yaw

They also allow stick and pedals to go back to the neutral position

Pitch AFU (artificial feel unit) particularity..

It has two override springs providing an increased load factor authority for stick movements beyond the soft top allowing 25% extra pull, use in emergency because will go after g a/c limit

PIT (pilot input transducers)…

Convert pilot input in electric signal for FCC which provide command inputs to primary surfaces and LEF

Primary actuation system

5 primary actuators:

• 1 rudder

• 2 ailerons

• 2 horizontal stabilizer

Quadruple independent electric lines and quadruple transducers for feedback signals

All supplied by 2 independent hydraulic systems

Rudder +\- 30

Aileron +\- 30

Horizontal tail +15 (nose down) / -30 (nose up)

Secondary actuation system consist…

Leading edge flaps actuation system (LEFAS)

Trailing edge flaps actuation system (TEFAS)

LEF surfaces excursion in deg

0/-30 deg

LEFAS details

Dual hydraulic and dual duplex electrical system based on quadruplex FCC architecture

Powered by PDU ( power drive unit), divided in 2 sections each receiving hydraulic supply from an independent hydraulic system.

2 hydraulic motors give power to 6 rotary actuators (3 per wing) through left and right wing power lines. The 2 outboard rotary actuators have transducers for position feedback to FCC

If asymmetry is detected in LEF

LEFs are disengaged

LEF position as a function of the flight phase

In UP (cruise) with landing gear down

If CAS < 65 kts — retraction to 0

If CAS > 55 kts — extension to -20

TEF positions

UP — 0 deg

T/O — +20 deg

LAND — +40 deg

TEFAS characteristics…

Single hydraulic, dual electrical system based on quadruplex FCC architecture

Powered by PDU (power drive unit)

Receive supply by left hydraulic system

Hydraulic motor provide mechanical power and 4 screwjack actuators 2 per wing

On the outer end of actuators there are duplex position transducers for position feedback to FCC

TEF protections

TEF are

• automatically retracted to T/O position at 205 kcas

• Automatically retracted to UP position at 235 kcas or IMN above 0.41

FLAP RETR caution and audio message

protection prevents flap extension if selected above speed limit

Protection non reversible, if active and you go back to the envelope you must match flap position and then extract again

ALPHA FAIL mode not affected

FIXED GAIN mode:

• LG UP — TEFAS extension is prevented by auto retraction function

• LG DOWN — TEFAS automatic retraction is not available (no protection against envelope exceeding and possible resulting structural damage)

CSD

Control surface display

Where speed brake and TEF and LEF info are displayed for the pilot

Airbrake technical characteristics…

Single hydraulic, dual electrical system based on a duplex FCC architecture

Primary function: a/c deceleration, speed control, assist maneuverability

Airbrake hydraulic actuation system (ABHAS) consist of:

• 1 hydraulic power module powered by right aircraft hydraulic system and controlled by a control module

• 1 actuator fitted with a duplex transducer for position feedback

Airbrake Numbers

Max Airbrake extension at low speed is 50deg (40deg TEF in LAND position)

With LDG GEAR UP Airbrake provides dynamic extension and retraction when the aircraft is aggressively maneuvered to maintain carefree capability.

Airbrake symbology on HUD

2 static symbols are displayed on the velocity vector (FPM and CDM) to indicate open and fully open Airbrake

Aircraft trimming capability

Above 150 kcas and with LDG UP autotrim for pitch attitude

FCS (flight control system) functions:

• air data sensing and computing

• Control and stability augmentation

• Aircraft trimming

• Configuration control

• Carefree handling

• Autopilot and flight director

OFP

FCS Operational flight program

FCS operational modes:

• normal

• Alpha fail

• Fixed gain

Normal mode

Assures carefree handling within the aircraft envelope

Alpha fail mode

Switched automatic in case of loss of AOA (angle of attack) or AOS (sideslip angle).

AOA and AOS are replaced by inertially derived ones Calculated from AHRS

Envelope is limited in terms of AOA and carefree is not available.

Functions affected:

• data sensing and computing

• Control and stability

• Carefree

• Autopilot/flight director

Fixed gain mode

Switched automatic in case of failure of air pressure signals

Pressure signals replaced by default pressure data and set at their safe “fixed gain” condition

See. Table in picture

Transition from normal mode to fixed gain mode takes from 2 (below 200 kcas) to 30 seconds (above 250 kcas), in this period pressure data are held to the last valid data sensed.

If the failed status persist system transit to default pressure values.

Basic authorities (Nz and roll rate) for LG UP are reduced to 50% to allow a safe return to base, within a restricted flight envelope.

Pilot should not exceed the flight envelope because it can bring big instability to the aircraft.

CAS, AOA, Mach number, VSI are removed from HUD and CADI.

GPS altitude, estimated AOA and ground speed are displayed instead of air data.

THE ONLY PILOT REFERENCE IN THIS MODE IS ESTIMATED AOA UP TO 45 deg pitch

Air data module (ADM) modes:

• Normal mode

  no failures in the system

• Flow fail mode

  more than 1 IMFP has failed flow angle values so you loose AOA

• Loss of function

  more than 2 failed probes on pressure e vengono rimosse tutte le cose dal hud

• Low speed mode

  se la velocità è più bassa di 50 nodi il sistema fa vedere 40 nodi

• Freeze mode

  quando si verifica una situazione di out of envelope e si free amo tutti i valori

DIRECT LINK

Between 55 and 75 kcas pilot has full authority on the stick to better control the aircraft.

(75 kt normal control laws are fully active, at 55 kt control has fully reverted to direct link, at 65 kt 50% of control is normal and 50% direct link)

Direct link on HUD CADI and audio message

Direct link can be active up to 90 kt if air data is in freeze mode

CAREFREE PROTECTION ARE GUARANTEED DOWN TO ….. ONLY

100 kt

MAMS (mass and store management system) function

Parto of control laws module (CLM) In the FCS

It operates in auto and manual mode

• Auto: default mode of operation, pilot input are limited to the ground start-up initialization

• Manual: mass estimation backup mode, designed to maximize operational capability in case of failure

Carefree handling functions:

• Protection against departure from controlled flight excessive AOA AOS combinations

• Protection against airframe overloading

• Protection against GLOC

• Protection against primary control surfaces overload

• Protection against structural overstress of TEF

• Limitation of Airbrake extension

See table in pic. For scheduled limitations for different configurations

AFU

La stick sono collegate a queste artificial feel unit che danno la sensazione di star pilotando e hanno due override springs che permettono di avere 25% extra authority

DIRECT LINK

LG UP e se deceleri tra 75 e 55 kt le control laws diminuiscono fino a entrare in questa modalità dove la connessione tra i comandi del pilota e le primary surfaces sono dirette

CAREFREE

Le protezioni sono garantite fino a 100 kt. Sotto questa soglia si riducono fino ad arrivare al direct link in cui si può entrare in vite

DOUBLE ENGINE FLAMEOUT MODE

Modalità in chi la pressione idraulica viene distribuita in modo da garantire una safe recovery

MAMS

Serve a migliorare le performance e vengono calcolate automaticamente dal sistema

Aircraft mass and store management function

MAMS architecture

Fa parte del control laws module dell FCS. Può operare in auto e manual mode

Auto: pilot inputs limited to the on ground start-up initialization

Manual: maximize operational capability in case of failure

MAMS operative mode

Cross check successfully and system enters the auto store operative mode.

Pilot can decide if auto or manual

Se il sistema vede problemi l auto mode non si può mettere

MAMS fail - safe mode

Se il sistema é in auto mode e si ha una failure passa in fail-safe.

Il pilota può decidere di rimanere in fail-safe o passare al manual mode

Il pilota deve stare attento all RTB envelope da seguire per rientrare a casa

MAMS during refueling

Durante il rifornimento FCS monitoring sono sospesi e si deve fare una reinizializzazione della massa alla fine del rifornimento.

Ci sono tre condizioni in cui la fase di refueling inizia e devono verificarsi tutte e 3:

• A/R button pressed

• FCP air refueling ready signal

• Transfer valve open

3 casi di air refueling

Wet docking

Dry docking

Soft contact

Wet docking

Standard performance

Dry docking

Refueling valve open ma non avviene il rifornimento

Soft contact

Dopo un soft contact la valvola di rifornimento non si apre e il sistema non entra in refueling mode.

Non serve settare la massa quindi non serve la conferma del pilota

Carefree

Assicurato in normal operational mode

Offre diverse protezioni:

Departure from controlled flight

Airframe overloading

G-LOC

Primary control surface overload

Structural overstressing

Limitation of Airbrake extension to protect airframe loading and stability

Roll priority function

Sopra i 350 kts

Pedal authority suppressed

Below -1 / +5

Above -5/+15

Carefree training modes

3 modes

1 2 3

PARS

Pilot activated recovery system

Pars cosa fa

Provides automatics recovery to straight and level flight with small positive climb angle

Does not provide terrain-avoidance and speed protection

No autothrottle

Si disattiva facendo un escursione di più del 75% con la stick o premendo il paddle switch

PARS type of recoveries

Upright

90 deg bank

Inverted

Pull

Pars special alerts

ATTITUDE RECOVERY

Failure indications

FCS 1 FCS2 FCS 3

failure of single non essential equipment

Failure that require immediate action

Failure of single or multiple equipment

FCS 1

Failure of first air data failure in flight that leads in loss of carefree

FCS 2

In case of a second failure of the same essential function that reduces level of redundancy

FCS 3

In case of a third failure of the same essential function that reduces level of redundancy. FCS has lost system integrity and operations are compromised

FCS RESET

If a failure of essential function clears, this advisory trigger and normal operation can be manually restored by pressing the FAIL/RST push button on the FCS/TRIM control panel

Moderate to severe turbulence

AOA limit carefree non si può usare