SAAB 340 Tech Course

2022-11-302025-07-16

Aircraft General

25,000ft – Pressurised except radome, nose wheel, tail-cone
340B – CT7-9B – 1750 shp (1870 w/ APR) / 1935 eshp @ sea level up to 35˚

C1 – 510kg
C2 – 270kg
Total 780kg

Warning Annunciator System

Ordering:

1. STALL,
2. AP DISC,
3. ENG FIRE,
4. CONFIG,
5. MSTR WARN,
6. ALT,
7. MSTR CAUT,
8. OVRSPD

Warning Electronic Unit – WEU

Has BITE (built in test integrity) – will illuminate BITE LIGHT (Test 1 panel) if channel fail

Take-off Inhibit

Reduces all alerts:

• Allows all warnings (auto-trim inhibited)
• Inhibits all cautions (except park brake, gust lock, auto coarsen)
• Stall pusher is not enabled until 7 seconds after T/O

T/O inhibit is engaged during engine start (55% Ng disconnect w/ start cut)

T/O inhibit is reset automatically when:

• landing gear retracted,
• with button,
• GND OP 

Electrics

• 28V DC (Main Electrical Power)
  • 2x 28VDC Starter / Gen
  • 2x 24VCD Ni-Cad Batteries
  • External Power Supply
• Emergency Power
  • 24VDC 5Ah battery
• 115V/200VAC WILD Gen
  • 2x 115VAC Gen for ICE ONLY
• 115V/26VAC Inverters
  • 2x 400Hz inverters (DC -> AC)

Power Supply

Main Electrical PowerEmergency PowerStarter / GenWild GenInverters

To energise BAT relay:

• BAT switch on,
• Ext power relay must be de-energised,
• BAT temp below 71˚C

57˚C + = ‘NO BAT START’
71˚C + = ‘L/R BAT HOT’ (BAT relay will open)

Battery compartment has fan, disconnected in flight

Starter / Gen - With one Gen working, UTILITY BUS IS SHED

External Power

28-29.5 VDC (overvoltage protection at 31 VDC)
Requires 10 VDC to close, start abort at 7 VDC

EXT PWR has priority over battery and gen relays
If GND PWR on, L/R BAT light will illuminate because relays have been de-energised

1x 24 VDC 5Ah rechargeable D cells

Avionics rack, 1hr duration, integral heater
Requires either BAT switch to be energised
When L BAT Bus is powered, emergency battery will charge
Powers emergency bus when L BAT Bus voltage drops below 24 VDC

EMER PWR light will illuminate if:

• Emergency battery voltage drops below 24 VDC,
• Emergency bus is not powered,
• Emergency BAT is not being charged

EMER Bus:

• L/R fire detection (inc. tailpipe)
• Warning sys
• Stby Horizon
• VHF Com 1
• 28 to 5 VDC converter (inst emerg lighting)
• Bus tie relay CONN function
• Emerg voltage indicator
• Audio sys backup

To energise:

• Start completed
• EXT PWR relay de-energised
• Gen output higher than gen bus voltage
• Gen switch on
• Field relay reset

Cooled by integral fan (GND), ram air in flt

If Gen temp reaches 150˚C, GEN OV TEMP will illuminate (NO AUTO DISC)

With only one gen, utility bus is shed

For ice protection only
Driven from PGB

Receive power from L and R main busses
MAIN INV light will illuminate if selected 115 VAC inverter fails, or in off position

2x Gen Control Units

Control and protection of DC starter and gen (in both modes)
GCU will de-energize a gen relay (offline) when:

• Over voltage (>40VDC)
• Short circuit
• Reverse currents
• Fire handle pulled

2x Power Distribution Units

All sources of power run through PDU (except emergency power)

• Bus Tie Relay (left)
• Series/Parallel relay  

Bus Tie Relay

1 GEN OR LESS, BUS TIE ON

Allows:

• EXT PWR to energize all busses when on (e.g. L AVON Bus – cannot be run off battery)
• One gen to energise all busses (WILL NOT POWER UTILITY)
• Connection of two batteries

To energise BUS TIE relay, need left battery switch on, or GPU on (GND goes through left PDU)
If current from 1 gen bus to another exceeds 800A, tie relay is de-energized (inhibited during engine start – 1600)

Bus Tie Relay MUST be checked for integrity:

• Before turning a gen switch on – check BUS TIE light on
• After turning a gen switch off – check BUS TIE light on

Series / Parallel Relay

Energized during battery start to connect batteries in series (48VDC)

Lighting

Dome connected L Hot Bat Bus

Taxi Light

Then taxi light switch is on and nose landing gear is down AND locked, the taxi light is energised through the L BAT bus Note – taxi switch runs from MAIN bus so needs better than bat

Emergency Lighting

Emergency Battery will supply power to light emergency instruments:

• Attitude Indicator
• Airspeed
• Altimeter
• Compass
• VOR/ ILS
• Cabin pressure

If L BAT bus is not powered, emergency power supply powers emergency bus
To illuminate these instruments, EMER LIGHT switch on overhead panel must be in armed or on

Fuel Systems

4 cells (2 per side) making up L + R tank
2542 kg max useable (all gauges are useable fuel)
SG of 0.79 kg/L

Fuel is picked up from inboard cell

All gauges are useable fuel

Fill Sensor

Low Fuel Indication = 135kg ± 30kg
6 probes, resistance type

Refueling

Blue refuelling light indicates:

• Refuelling panel is switched on,
• De-fuelling valve is on

Standby Pump

Inside hopper tank, pumps fuel to engine

Supplies engine with fuel during start until main pump can supply sufficient pressure (approx. 10 psi)

Automatically activated (via differential switch) in event of main pump failure

For shutdown, CL inhibits STBY pumps from auto activating

Main Pump

Draws fuel via suction (negative pressure) to high pressure vane pump inside HMU -> high pressure fuel to engine

Positive pressure sensor will light the green STBY PRESS light (indicates positive pressure, not pump)

1 differential pressure switch illuminates MAIN PUMP light on overhead panel when pressure drops below 10 psi, will give CWP Master Caution
STBY pump will turn on at 5 psi

Fuel Heater

Uses PGB oil to heat fuel

Filter

Filter before HMU
Impending bypass sensor, activates fuel filter light on overhead, when differential pressure across filter reaches 9 psi (actual bypass occurs at 18 psi)

Fire Protection

Engine Fire

Single continuous loop detection circuit below engine
Power supply for detection system is emergency bus
Extinguishing system runs off L and R Hot Bat bus

Slow Resistance Change = actual fire
Quick Resistance Change = short circuit  locks out fire warning FIRE DET fail CWP

Consists of 2 Halon 1301 fire bottles @ 550 psi

When pulling fire handle:

• Engine Fire Wall Shutoff Valve is closed,
• Engine bleed air LP/HP is closed,
• Start-Gen FIELD relay is opened,
• Fire bell silenced,
• Master Warning is reset,
• Both main / reserve fire extinguisher squibs are armed

Indicated by:

• Master warning (flashing)
• ENG FIRE light on CWP
• Fire handle
• Aural fire bell warning

Handle remain illuminated as long as condition remains

Tailpipe Hot

3 thermal switches in parallel
Only 1 is needed to activate master warning and illuminate L/R Tail Pipe Hot CWP
Switches are calibrated to close at 235˚C

Cargo Fire

Normal pressure is 360 PSI

When bottle pressure drops to 260-310 psi, white CARGO EXTG light on O/H panel illuminates (about 15 min of the total 30)  

Pneumatics

Supplied air to Aircon, Pressurisation, De-Ice boots
Bleed air is taken from:

• LP – behind 5th compressor stage
• HP – behind 6th compressor stage (centfugal)

HP Valve - pneumatically actuated, requires 10psi of bleed pressure to operate
LP Valve - pneumatically actuated, requires 10psi of bleed pressure to operate

HIGH PRESSURELOW PRESSURE

CWP – will illuminate L/R HP HIGH if the bleed fails to close

Closes when:

• Bleed air after pre-cooler exceeds 288˚C
• Fire handle pulled
• HP valve switch is closed
• Bleed air greater than 76 psi except Mod 2310

WILL FAIL CLOSED

Can be opened on GND:

• Ambient temp is greater than 20 degrees C AND
• ITT limited to 800 degree C (company requirement)
• Do this procedure carefully as ITT over temp can occur

Pre-cooler - used to cool the HP air
Air - scoop from engine nacelle
Ground - WoW switch. Jet Pack creates under pressure behind the pre-cooler

Closes when:

• Bleed air after pre-cooler exceeds 288˚C
• Also if ACP compressor discharge temp exceeds 225˚C, distribution duct exceeds 82˚C (will give DUCT OVR TEMP light)
• Fire handle pulled
• Bleed valve switch is closed
• Regulate pressure exceeds 43.5 psi

WILL FAIL OPEN

Confirmation of closure LP Valve with BLD CLOSED and AIR COND CWP (will give master caution)
CWP – will illuminate BLD FAULT and AIR COND if the bleed fails to close

BLD FAULT will indicate:

• If bleed air temp exceeds 288˚C
• If regulated pressure exceeds 43.5psi
• When the temp or pressure goes down after the bleed has been closed, the BLD FAULT light will extinguish

3 scenarios:

• Fault ON + Valve closed = Over temp
• Fault ON, then OFF + valve closed = High pressure
• Fault Only = Faulty valve

Air Conditioning

Hot regulated bleed air enters the air conditioning pack (ACP)

Temp Control Valve

Auto maintains 18˚ to 29˚, protects duct temp by keeping them b/w 3˚ and 75˚

To open pack valve fully, hold cold for 8 seconds
Open bypass valve fully, hold hot for 4 seconds

Overtemp

2 OVR TEMP switches in each ACP, if over temp occurs, bleed valve will close and L/R DUCT OV TEMP will illuminate

Recirc Fans

Recirc of cabin / cockpit done with 2 recirc fans, suck through floor grills.
Fed back to respective ACP

If fans drop below 80%, recirc light will illuminate on overhead panel (no CWP)

Ram Air Intake

A/C can be dispatched wit only 1 ACP, but RAM air needs to be open, (used as backup if last ACP fails)
Pressure build up via ACP keeps RAM closed, if fails, allows fresh air to flow in
NO PRESSURISATION, Min 210 kias

Pressurisation

2 outflow valves in empennage

Primary – electro pneumatic
Secondary – pneumatic

Emergency Dump – Flight primary opens fully, ground both open fully

System receives from 6 places – press dump, alt set, power levers, wow switch, etc

A – altitude for landing elevation
B – barometric selection knob
R – rate

Cabin rates from 50 to 2500 up, and 50 to 1500 fpm down, can be set by the cabin rate knob
Detent is 500 up, 300 down

Rotating open knob CW – cabin alt increases, pressure diff decreases
Rotating open knob CCW – cabin alt decreases, pressure diff increases

1. Ground Mode
   a. Both valves closed via spring
   b. After start, primary open, secondary closed
2. Pre-Pressurisation Mode
   a. 1 pwr lever advances above 64˚ PLA, system transfers to pre-pressurisation mode:
   i. Primary moves towards closed, cabin pressurises 300ftm until 140ft below actual cabin alt
   ii. Secondary remains closed
   iii. Only for an ECS on T/O
3. Climb Mode
   a. WOW switch to go to climb mode:
   i. Primary auto-regulates
   ii. Secondary remains closed
   b. With both bleed valves closed, both outflow valves will be closed, until 1 bleed is turned on
4. Descend Mode
   a. When aircraft descends 200ftm in less than 1 min, or more than 500ft, switch descend mode
   b. Controller will begin downrate (secondary is closed)
5. Landing Mode
   a. Primary – cabin uprate of 500fpm, after 20s the valve is driven fully open
   b. Secondary – closed

Emergency Equipment

Fixed

Supplies oxy via 3 cockpit outlets to crew, and via 4 pax outlets
Oxy bottle has 1390 L, normal pressure of 1850 psi (regulated to 70 psi) (has pressure relief valve)
Min dispatch pressure 1040 psi

Emergency Light

When you have one gen or better, lights will be off
Power is provided by 5 rechargeable batteries, under the floor, called “Jet Packs”
1 min use requires 1 hr flight time for recharge
Kept fully charge by R ESS BUS

ELT Activation

5 – 7G

Hydraulics

Main Reservoir

Pressurised by internal spring and emergency accumulator pressure – has relief valve

Hand Pump

Fluid discharged by hand pump returns to main reservoir
Double action pump
Open door, place pump handle in position, place gear / flap down, select where to send fluid, pump

HYD Pump

Auto Mode

Better than BAT
Will operate in AUTO mode when:

• Main accumulator pressure drops below 2100psi until 2900psi is reached
• LDG is selected DOWN and until left main gear is locked down
• Landing gear is selected UP and until both main gears are locked up

Override Mode

Will run on BAT
Run continuously, delivering 3000psi

Accumulators

4 HYD accumulators – absorb pressure surges, overpressures, store pressure to enable on demand operation
Pre-charged with nitrogen to 1650 psi

• Main (flaps / gear / NWS)
• Emergency (emergency uploads actuator / pressurises main resvoir) – ONLY SUPPLIES EMERG LANDING
• Outboard brake
• Inboard brake

Has thermal relief function, if thermal expansion increases any Acc. pressure to 3900psi, dump valve opens and pressure is released to return line

Alerting

CWP – Hydraulic master caution when:

• any accumulator drops below 1800psi
• main reservoir temp reaches 116˚C (turns off at 93˚)

Signs of U/S pump:

• Unusual length of time required to extend or retract gear
• Frequent pump cycles when hydraulics system components not in use
• Unusual sound emitted from pump

Duty limit – shouldn’t run more than once every 6 min on ground, 15 min in flight

Landing Gear and Brakes

Max tyre speed 165 KIAS

Gear

Gravity Extension – pulling red handle, pump HYD to open up locks and blow door bolts or HYD pump
EMER accumulator pressure is used to release locks
When gear is DOWN AND LOCKED: down lock actuator mechanically engages the down lock at extension, and is HYDRAULICALLY released prior to retraction (gear is not held down hydraulically)
Micro switch in upper drag brace senses the down and locked condition and illuminates the light
Gear extended = locked down by spring loaded down lock at pivot point of upper + lower drag brace when straight

Gear Up Sequence:

• Hydraulic pressure – down lock actuators pressurised and released
• Hydraulic pressure is ported to gear actuator, the gear begins to retract
• The up lock roller on the shock strut – engages the up locks
• Gear is now held MECHANICALLY by up locks

Gear Down Sequence:

• Hydraulic pressure – up lock actuators are released by hydraulic pressure
• Hydraulic pressure is ported to gear actuator, the gear extends
• Down lock actuators engage the down lock by spring force
• Dual down lock assist springs connected to the drag brace assist down locking, which occurs when the drag brace is straight. This helps pull the gear over centre (elbow joint, like DC3)

Gear handle position has no effect on EMERG extension, but need down for anti-skid braking and disagreement light

Wheels

Tubeless tyres – all have thermal relief plugs – 180˚C

Anti-Skid

Only works above 20kts
Available in emergency braking
If Anti-Skid is off, will come up as A-SKID inop (do not brake above 40kts)

Touchdown Protection – prevents braking if:

• Either WOW switches sense ground position or
• Associated PWR lever moved aft of flight idle

AND

• 3 second delay or
• Average wheel speed above 50 KIAS

Prevents locked wheel – if slowest wheel is 50% or less than other, full brake release signal is sent to that circuit

Park Brake

Get CWP with PARK BRAKE ON
Light illuminated when exceeding 1700 psi, goes out when pressure decreases below 900psi
However, can be set on at 1500 without CWP, and can have the brake go off at 950 psi, but light still remain

Tiller

Pushing tiller engages steering valve solenoid which allows hydraulic motor to transmit via planetary gearbox
Can turn through ±60˚, ground handling lockout can turn through ±120˚

Config Warning

Will get config warning when:

• Gear UP
• Below 500ft RAD alt
• 1 PWR lever below 64˚ PLA

Can be cancelled by pressing master warning
Will get another config warning when:

• Gear up and
• Flap 20˚

Cannot be silenced, must select gear down or retract flap  

Ice and Rain Protection

De-Ice Boots

Three distribution valves are used in boots, each distribution valve is equipped with:

• 2 Solenoids – allow pressure to be distributed to each boot
• Ejector – creates negative pressure (-2 to -2.3) (when not receiving inflate signal) keeps boots flush w/ wing
• 2 Pressure switches – monitor de-ice function and illuminate lights

2 shutoff valves downstream of pre-coolers normally open (fails closed)
Controlled by common switch marked AIR SUPPLY
Are inflated in sequence, stab, out, in, stab (6 seconds per stage)

May be inflated with:

• Spring loaded ONE cycle position (stab,out,in,stab – 6 seconds each section) w/ 5 second reset time
• Latched CONT position (stab,out,in,stab – 6 sec each section then rest for 156 seconds) 180 sec cycle total
• Manual inflation (cannot dispatch into ice without others) must hold button to inflate and count 6s

28 VDC timer light monitors time and will:

• no pressure sensed downstream from valve w/i 4 seconds
• activated timer gives no inflation signal
• boots not cycling
• pressure remains in stabiliser boot zones
• pressure remains in both inboard / outboard after 8 second
• control power to timer is lost
• pressing one of the manual cycle buttons while in CONT or during a cycle will result in TIMER light momentarily

Most likely, timer light means there isn’t enough air getting to the boots (not inflating / deflating fast enough)
DE-ICE OV TEMP warning at 150˚C, does not auto-close

Prop

115 VAC wild gen
Prop de-ice (<-5 off, -5 to -12 norm, <-12 max)

• Norm – 11s on, 79s off (alternating blades, 2 at a time)
• Max – 90s on, 90s off

Switch must be returned to off position between selecting different settings (resets timing)

Timer will auto disconnect and illuminate L/R prop light if:

• AC / DC power fail
• Timer not cycling or remaining on
• Over / under current to boots
• Cycling interval periods faulty

BLUE L/R PROP DE-ICE light – will illuminate by STATUS, indicating prop de-ice is working

Engine Anti-Ice

• 115/200VAC ‘Wild’ (For inlet lip, inlet ducts including Inlet Protection Device) (L/R INTAKE light)
• Engine Bleed Air (L+R Engine Anti-Ice Start Bleed Valves) For Split lip and Inlet Guide Vanes (L/R AIR VALVE light)

BLUE ANTI-ICE Light – will illuminate SWITCH POSITION, indicating engine anti-ice is on
Hot scavenge oil is always active through scroll
Fail in intake anti-ice = L/R Intake light illumination

Both ducts L/R INTAKE light will illuminate (regardless of whether the Engine Anti-Ice is switched on or not) with:

• Loss of more than 1 Primary / Backup Sensor, or 1 Primary + 1 Backup Sensor
• Loss of DC Power (used for control functions)
• Loss of AC Power (heating part of system)
• A sensed over/under temp
• Failure of 1 or more heating elements (short circuit)

AC Gen fail = engine intake anti ice lost on that side

Diagram:

• low power: regardless of anti-ice position, BLD air will always go to inlet guide vanes / split lip
• high power: BLD air is not able to reach inlet guide vanes / split lip (unless engine anti-ice is on, where it will go to IGV / split lip – get an increase in ITT and drop in torque)

Low power = already take air to give biggest stall margin, thus at low power not much ITT/Torque change
Above picture depicts the sleeve valve, which moves in proportion via the HMU based on the PLA via direct mechanical link. The valve (internal part) moves up at high power, which blocks the IGV/Split Lip/Eductor. The valve moves down at low power, which allows air to flow to IGV/Split Lip/Eductor (even without selecting any ENG ANTI ICE on). The solenoid at the bottom (ENG ANTI ICE switch), when switched off, sits to the far right, blocking air. When switched on it moves to the left allowing air to the IGV and Split Lip. Eductor = the exhaust part of the AISBV – air vents overboard on start.
START part of AISBV sends air overboard on start from compressor to ensure no compressor stall on start (smooth air supply)

Engine Anti-Ice switch OFF/Solenoid Valve Closed = No Anti-Ice flow
Engine Anti-Ice switch ON/Solenoid Valve Open = Anti-Ice flow

Windshield

Heating from 115 VAC wild
Heating monitored / controlled by L/R Heat Control units
The L/R FRONT or L/R SDE lights will illuminate, along with an associated Master Caution CWP, when an overheat or controller fault occurs
Has 3 sensors: normal, over temp, spare
Regulated to 35˚C

Front – anti ice
Sides – defog – must be selected to NORM for 7 min before High (high inhibited on gnd by WOW)

Power Sources

AC WILD – 115/200 VAC WILD GEN
Engine intake, prop boots, windshield, sensors (L/R main pitot, AoA, TAT)
Protected by GCU against over / under voltage, under frequency
Must be at least 1,000rpm to energise Gen control relay
Can transfer load if one fails (intake anti-ice will not transfer, that side is lost)
AC GEN light illuminate when not supplying power (including less than 1,000rpm)

Bleed Air

• Wing Boots
• Tail Boots
• Engine inlet guide vanes, split lip (anti-ice)

Air taken from behind 5th compressor stage through Engine Anti-Ice Start Bleed Valve, other side of LP
DE-ICE OV TEMP – 150˚C

Flight Controls

Primary – Elevators, Ailerons, Rudder
Secondary – Trim (electric), Flap (electrically controlled, hydraulically actuated)

Elevator

2 control channels (left operates left elevator, right for right)
In tail, the two are mechanically interconnected

Can disconnect if one channel becomes jammed:

• Momentary disconnect – increasing stick to breakout point of spring
• Permanent disconnect – disconnect panel in cockpit

Autopilot is connected to left channel

Aileron

2 control channels (left operates left aileron, right for right)
Can disconnect with electrical signal
Auto pilot is connected to right channel
Similar in terms of trimming methods

Rudder

Assistance from spring tab (helps you when you need help)
Rudder pedals are mechanically linked to tab
At low forces, tab moves with entire rudder, but high, moves opposite to help in deflection

To prevent rudder overload conditions:

• Resulting from excessive rudder pedal displacement or
• Resulting from excessive control forces at high speed

System includes rudder limiter control unit:

• lower than 150 kias – no restriction
• 150 – 200 kias – 15˚ rudder movement
• greater than 200 kias – 6.3˚ rudder movement

Failure in the system – RUDDER LIMIT on CWP (can be overridden with RUDDER LIMIT set to OVRD, will fail off)
Autopilot is linked to rudder control system

Trim

Trim tabs geared to elevator by trim tab actuators
Trimming can be achieved by control column (normal) or pedestal (standby trim)
Normal trimming actuates left trim actuator which operates left trim tab
Standby trimming actuates right trim only, which deactivates pitch trim synchronising
Pitch trim synchroniser trims right tab to same position (can fault or turn off, illuminate PITCH TRIM on CWP)
To reengage pitch trim sync, press PITCH RESET (will only work if 1 unit apart), will move right trim

Gust Lock

Aileron + Elevator = locked mechanically
Rudder = locked electronically

Gust lock CWP Illuminates if gust is off but rudder is still engaged (will fail disengaged position)

Flaps

Single slotted flap
Mechanically interconnected, hydraulically operated, selected by electric handle
Sends signals to Flap Control Unit, which controls flap control valve
Relays flap position signals, detects faults
Should a fault be detected, shuts off the electrical supply to the flap control valve (FLAP CW)
If forces become too high, relief valve will let pressure out (at 2,200psi)
Asymmetric flap is not possible in SAAB (split flap is possible)

Config

Condition levers, flaps, trim (green range, less than 15)

Instruments and Recorders

Air Data System

ADS displays parameters associated with air mass (airspeed, altitude, V/S, air temp)

System components:

• Air Data Computer (ADC)
• Servo Altimeter (servo = motor driven) (FO has pneumatic instrument)
• Servo Airspeed Indicator (FO has pneumatic instrument)
• Instantaneous Vertical Speed Indicator (only Captains side)
• Altitude Preselect Alerter (APA)
• Temperature/TAS Indicator (cannot get temp on gnd)

We get: Alt, VS, IAS, SAT, TAS, Vmo
ASI Warning Flag – will show when test is pressed, IAS indicator fails, loss of airspeed from ADC
Standby AI – Electric gyro, powered off emergency bus (needs battery switch on), ESS AVION need to be on, Battery ON, 18,000 RPM

DFDR

Event marks the tape, analogue data is sent to the FDAU, then to the DFDR
25 hours of data, own ELT (30 days)
Powered off L/R INV BUS 115 VAC, backup power EMER AVION BUS
FDAU - Starts recording as soon as engines are on and one gen is online

CVR

Erase only works with gust lock on ground
Records last 30 min
An inertia switch switches CVR off at 2.5G (longitudinal measurement, not downward measurement)
Operates as soon as L BAT and ESS AVION switches are on

Autoflight

CAT 2 ops require 2 MSP, fast / slow speed pointer, AP transfer capability
AP provides 3 axis auto pilot: yaw damper (reduce tail float), flight director, BITE and diagnostic test

Flight control computer interfaces with:

• ADC
• AHRS
• NAV radios
• EFIS
• APA

Engaging AP will engage YD and elevator and rudder auto trim (no aileron trim)
Before engaging AP, have FD bars displayed
Difficulties trimming out forces come up with RUD/AIL/EL on EADI’s
Will always get AIL after engine fail unless re-trim

The Flight Director modes can be:

• Active (captured displayed in cyan) eg VSI
• Armed (annunciated White) capture modes heading

Halfbank

Reduces normal bank angle from 27˚ to 13.5˚

Is suppressed at APPR LOC/VOR capture
CANNOT be selected for precision approaches

EFIS

Attitude and Heading Reference System (AHRS)

Consists of:

• 2 Attitude and Heading Computers (AHC)
• 2 Flux Detector Units (FDU) magnetic field information
• 4 Inertial Reference Unit Sensors (2 per AHC) angular rates, linear accelerations
• Inputs from the Air Data System (ADS) TAS/IAS/VS

During initialisation of the AHRS, the aircraft must NOT be moved
AHRS initialisation takes approximately 70 seconds

Display Processing Unites (DPU)

Receive control inputs from display control panel, DPU will adjust display panel
Every A/C has 2 DCP, 1 for each DPU
Sends video signals to the EASI/EHSI

Multi Functional Display (MFD)

Has its own symbol generator
MPU receives signals from both AHC (attitude and heading computers)
MFD can display:

EFIS Requires

L/R avionics start buses energised L/R AVION switches ON Better than battery power

Screen Fail

If both screens on one side fail, most likely DPU fail – put EFIS switch in DRIVE XFR
If one, most likely a fail of the screen – put EFIR towards operating display (i.e. bottom screen blank, move up)
With 4 screens, if captains side fails, XFR will steal FO screens including all FOs settings
With 5th screen, MPU will drive the failed side, all DCP controls function as normal

AHRS Fail / Revisionary Modes

ATT / HDG symbols indicate failure of Attitude and Heading Reference System (AHRS)
Select XSIDE DATA (not the screen, because the data is unreliable) switch on the failed side
Other (working) side AHC now supplies AHRS information to both sides
Pitch/Roll/HDG comparator cautions are now inhibited
When using XSIDE DATA, the DCP functions as normal (symbol generator is fine, the data on failed side is corrupt)
Will indicate data is being transferred from the other side

EADI/EHSI Flags and Warnings

Annunciators ‘flash’ red for 10 seconds, then steady

RED = RED/ YELLOW = AMBER
SPD = Speed Source Failure
FD = Flight Director Failure
XDATA = Cross side data not available (other crew is stealing your data, so you can’t use other data but your own)
LOC = Localiser failure/ No station reception (only if you have a frequency tuned, outside of range or failure)
RA = Rad Alt failure
GS = Glideslope failure
DPU = Display Processing Unit failure (Symbol generator failure. Complete or partial screen failure) (drawing picture unit)
VOR 1/ VOR 2 = Nav Source failure/no station reception. Middle of CDI indicator will disappear also
DCP = Display Control Panel failure (control panel for symbol gen failure)
HDG = comparative signal

The signals from each AHC are constantly being compared for accuracy

COMPARISON ERROR (and CWP) will display should errors be detected:

• Pitch/Roll/Heading
• Localiser/Glideslope
• Rad Alt
• Flight Director Commands

OTHER NOTES:
Indication of AHRS failure is a red ATT/HDG flag on the screens of the failed side  

Powerplant

Gas gen connected to compressor
ITT measured b/w Gas Gen Turbine and Power Turbine
Gas Gen – compressor / accessories
Power Turbine - PGB
OVR TEMP LIGHT – 962 (+3/-2)

Gas Gen

Gas Gen spool is Ng
Power Turbine spool is Np (prop speed through reduction gearbox, measured by freq of AC voltage from alternator)

Auto Ignition

• Flameout:
  • Ng deceleration rate equals predetermined schedule, ignition turns on 7s
  • Test on A – PL forward above FI w/ engines shutdown (ign illuminate)
  • Test on B – PL GI, CL fuel off, ign lights illuminate until 62% Ng
    (Auto IGN off @ 62% b/c engine running slow, don’t want fire)
• Np Overspeed
  • Np Overspeed – 1573 PRPM
  • Shuts of fuel to combustor, 5s delay, IGN on 7s
  • When Np decays below overspeed, fuel on again

Will illuminate on FSP due what you’d expect, but also if electrical control power is lost (auto ignition CB tripped)
If auto IGN lost, IGN light will come on, auto IGN activated, antiskid touchdown protection deactivated, BG will not be disabled for affected side, PGB oil pressure warning deactivated

Digital Electronic Control Unit (DECU)

• Np overspeed protection
• Flameout prevention (auto ignition)
• Signals Tq motor in HMU:
  • BG functions (1040rpm on gnd)
  • CTOT
• Indications in cockpit
  • TRQ
  • Prop RPM
  • ITT

Torque Motor

Increases fuel above current PL position for BG and CTOT

Bottom Governing

Present min PRPM on gnd:

• 1040 normal gnd
• 1200 reverse thrust (when blade angle passes -10˚)

Not enabled until CL passes MIN

Sequence:

1. CL advanced from START to MIN-MAX
2. PRPM passes 830
3. DECU enables BG and sends signal to Torque Motor to up schedule fuel to inc Np to 1040

NB – must be NO Ng increase b/f 840 PRPM, if Ng increases before 830, shut engine down (DECU failure) If PRPM drops below 280, DECU will disable BG (prevent engine acceleration by BG w/ feathered prop)

CTOT

Achieve selected Tq (CTOT), or Tq push (APR) – cannot reduce fuel flow
Must be ARMED (PL > 64˚) and ACTIVATED (CTOT panel)
Holds Tq until de-armed or de-activated, or by increasing PL above set Tq
Will avoid exceeding 955 or 975 / 115% Tq
Automatic Power Reserve – provide extra 7% in case of engine failure (will only bump from current CTOT position)
Activated by auto coarsen signal

HMU

• Schedules metered fuel for combustion
• Controls IGV and Variable Stator Vanes and AISBV to control air
• Ng overspeed protection (gas gen > 110% Ng, induces flameout, no auto relight. CANNOT RESTART)

HMU responds to:

• PL inputs (gas gen speed selection)
• CL inputs (fuel shutoff, Tq motor lockout)
  • Fuel shutoff – fuel is cut, manifold is purged of fuel (drained to enviro canister)

OIL SYSTEM

Not possible to overfill engine oil, will spill overboard
Engine allowed to burn 1 qt every 7 flt hours
Pressure transducer failure – oil pressure rapidly go to 0 or upper limit of gauge
Loss of oil – fluctuating oil pressure then drop in oil pressure, oil temp decrease (due air mixing supply line)
OIL LOW activates below 30psi (note – also comes on for PGB oil system)