Extra 500. Maintenance Manual (2012)

Cabin Leak Test

It is advisable to integrate the Dump Test in this test, because the necessary

preparations are very similar. Refer to Figure 21-1.

Detail Steps/Work Items

Key Items

Remove both upper engine cowlings.

Refer to Ch. 71-10-01/02.

Remove tail cone access panel.

Refer to Chapter 51-00-01

Plug the static reference port of the cabin

control outflow valve with tape.

Place an altimeter in the cabin, readable

from a window.

Set altimeter to 1013 mbar and note altitude.

Close the cabin door.

Remove inlet hose from the cabin inflow

box on the upper right firewall.

Risk of injury due to flying parts when pressurizing the cabin.

Warning

Follow cabin pressurization unit safety instructions before installing the

unit.

Apply Max. 5.5 psig air to the cabin.

Install a cabin pressurization unit or

equivalent to the cabin inflow box.

Let a helping person shut the cabin control

outflow valve by hand. Gently pull the valve

piston in its seat.

Pressurize cabin until altimeter reads

Tolerance +/− 500 ft

−3000 ft.

Switch off external pressurization unit,

engage stop watch and note altimeter

reading. Stop the time when altimeter

reaches the prior noted value.

Risk of injury when opening the door with cabin pressurized.

Door

Warning

could open with force.

Do not open the door until cabin has reached ambient pressure.

Calculate altitude difference and check if

Refer to Figure 21-2

time stopped is within limit.

Perform Dump Test if applicable.

Disconnect cabin pressurization unit from

cabin inflow box.

Re-install inlet hose to cabin inflow box.

Remove plug from static reference port of

the cabin control outflow valve.

Re-install access panels.

Refer to Chapter 51-00-01

Page Date:

21 Page 9

Upper Limit

1500

2000

2500

3000

3500

4000

Altitude Difference (ft)

Figure 21-2

Cabin Leakage Chart

Dump Test

It is advisable to combine this test with the Cabin Leak Test.

Refer to Figure 21-1.

Detail Steps/Work Items

Key Items

Remove both upper engine cowlings.

Refer to Ch. 71-10-01/02.

Remove tail cone access panel.

Refer to Chapter 51-00-01

Plug the static reference port of the cabin

control outflow valve with tape.

Let a helping person enter the cabin with an

additional altimeter.

Set altimeter to 1013 mbar and note altitude.

Switch BATT on.

Close the cabin door.

Remove inlet hose from the cabin inflow

box on the upper right firewall.

Risk of injury due to flying parts when pressurizing the cabin.

Warning

Follow cabin pressurization unit safety instructions before installing the

unit.

Apply Max. 5.5 psig air to the cabin.

Temporarily attach a cabin pressurization

unit or equivalent to the cabin inflow box.

Page 10 21

Page Date:

Detail Steps/Work Items

Key Items

Let a helping person shut the cabin control

outflow valve by hand. Gently pull the valve

piston in its seat.

Pressurize cabin until altimeter reads

Tolerance +/− 500 ft

−3000 ft.

Engage RH (outside) squat switch by hand.

Check if safety valve clicks and cabin

pressure drops.

Release squat switch.

Pressurize cabin again until altimeter reads

Tolerance +/− 500 ft

−3000 ft.

Position PRESS-switch to DUMP.

Check if safety valve clicks and cabin

pressure drops.

Switch off external pressurization unit.

Switch BATT off.

Risk of injury when opening the door with cabin pressurized.

Door

Warning

could open with force.

Do not open the door until cabin has reached ambient pressure.

Disconnect cabin pressurization unit from

cabin inflow box.

Re-install inlet hose to cabin inflow box.

Remove plug from static reference port of

the cabin control outflow valve.

Re-install access panels.

Page Date:

21 Page 11

21-10-00

COMPRESSION

Description

Refer to Figure 21-1.

The system consists of the engine compressor, bleed ports, a bleed air

manifold, a shut-off valve, a mass flow control valve, a mass flow controller, a

mass flow sensor, hoses, and the ENV AIR switch on the left side panel.

Engine bleed air is used for cabin pressurization. Bleed air is taken from the

engine compressor by means of two bleed ports. A forward-facing port is

located on the right top of the engine compressor scroll. On its left bottom

another downward-looking port is located. The bleed ports incorporate orifices

(sonic venturi) which are installed with special O-rings. Bleed air is then routed

through pressure hoses to the bleed air manifold located on the left engine side.

Just above the primary shut-off valve is installed, which allows switching on or

off cabin pressurization (and also heating) by means of the ENV AIR switch.

The mass flow control valve is installed above the shut-off valve. It takes bleed

air and/or ram air tapped from the left air-to-air cooler inlet to control the mass

flow. The valve is governed by a computerized mass flow controller installed

inside the cabin behind the side paneling between the cabin door and the pilot’s

seat. The controller receives mass flow data from the mass flow sensor

installed to a flange downstream the bleed air muffler.

21-10-01

Primary Shut-off Valve

Removal/Installation

The primary shut-off valve is screwed to the mass flow control valve. For this

reason it is advisable to firstly remove both valves together and to disconnect

them later by turning the shut-off valve.

Detail Steps/Work Items

Key Items

Remove LH engine cowling.

Refer to Chapter 71-10-01.

Disconnect bleed air manifold from shut-off

the valve.

Cut the electrical wiring from the shut-off

Reconnect later by splicing.

valve.

Disconnect the SCEET hoses from the mass

flow control valve.

Disconnect the electrical wiring from the

mass flow control valve.

Disconnect the mass flow control valve

4 bolts

from the engine mount and remove both

valves together.

Page Date:

21 Page 13

Detail Steps/Work Items

Key Items

Loosen counter nut between the two valves.

Unscrew the shut-off valve from the mass

Turn the complete shut-off

flow control valve.

valve. Watch the copper O-

ring.

Install in reverse sequence of removal.

21-10-02

Mass Flow Control Valve

Removal/Installation

Follow the procedure given in Section 21-10-01.

21-10-03

Mass Flow Sensor

The mass flow sensor is electrically connected to its control box located on the

nose gear firewall.

Removal/Installation

Detail Steps/Work Items

Key Items

Remove LH engine cowling.

Refer to Chapter 71-10-01.

Remove cable straps and tie tool wraps from

the electrical wiring between sensor and

control box.

Remove sensor.

4 bolts on muffler flange

Remove control box.

4 screws, 3 else connections

Install in reverse sequence of removal.

Check

Detail Steps/Work Items

Key Items

Remove LH engine cowling.

Refer to Chapter 71-10-01.

Remove sensor from muffler.

4 screws

Check 2 wires in sensor are intact.

Replace sensor if wires are

broken.

Install in reverse sequence of removal.

Page 14 21

Page Date:

21-10-04

Mass Flow Controller

Removal/Installation

Detail Steps/Work Items

Key Items

Remove left side armrest paneling.

Refer to Chapter 25-20-21.

Disconnect the electrical connector from the

mass flow controller.

Remove mass flow controller.

4 attachment nuts

Install in reverse sequence of removal.

21-10-05

Muffler

The muffler is directly mounted to a flange providing a holding fixture for the

mass flow sensor.

Removal/Installation

Detail Steps/Work Items

Key Items

Remove LH engine cowling.

Refer to Chapter 71-10-01.

Remove mass flow sensor.

Remove 4 screws.

Disconnect SCEET hoses from muffler and

flange.

Remove attachment bolts of hose clip and

hose clamp carrying muffler and flange.

Remove muffler with flange.

Install in reverse sequence of removal.

Page Date:

21 Page 15

21-20-00

DISTRIBUTION

Description

Refer to Figure 21-1.

The system consists of a valve box, SCEET hoses, a distribution valve, a

Bowden cable with a handle on the center console panel and the panel vent

fans.

Ram air or bleed air is ducted into the cabin (refer to Section 21-10 for the

bleed air system).

Ram air is taken from the oil cooler inlet on the right engine side and routed

through SCEET hoses to a valve box on the firewall. 2 check valves are

mounted to the valve box (ram air and bleed air side). Additionally the valve

box has a holding fixture for the duct temperature sensor. The cabin inflow

check valve is mounted between the valve box and the firewall.

Inside the cabin a valvular operated air distributor guides the air stream to the

windshield and/or legroom dispensers. The air distributor has also a holding

fixture for the temperature switch.

For better ventilation in the forward cabin section two vent fans are installed in

the LH and RH side of the instrument panel. Each vent fan sucks air from

behind the panel. On the discharge side each vent fan is connected to an

eyeball vent, which can be adjusted to direct or shut off the airflow. Two

switches, placed on the instrument panel near the resp. air outlet, control the

vent fans. The electric fan motors are protected by a 2 A - fuse.

The evaporators

(refer to Section

21-50) also work as cabin fans. Both

evaporator blowers work with different power settings in low or high mode.

21-20-01

Panel Vent Fans

Removal/Installation

Detail Steps/Work Items

Key Items

1 a (RH vent fan)

Remove RH IFD and right main panel.

Refer to Chapters

31-60-01

and 31-10-03

1 b (LH vent fan)

Remove LH and RH IFD and analogue

Refer to Chapter

31-60-01

engine indicator.

and Chapter 77-40-01

Loosen worm drive hose clamp on vent fan

casing.

Disconnect electrical wiring.

Remove vent fan with casing.

Disassemble vent fan and casing if

4 bolts

applicable.

Remove eyeball vent.

1 nut

Page 16 21

Page Date:

21-30-00

PRESSURIZATION CONTROL

Description

Refer to Figure 21-1.

The system consists of the engine compressor, two sonic venturi

(flow

limiters), a cabin control outflow valve, an unregulated safety valve, the cabin

pressurization/dump switch, the cabin pressure controller, the landing gear

squat switch, and two indicators, one for cabin altitude and differential pressure

and one for cabin rate-of-climb.

Pressurized air is supplied from the engine bleed air through the sonic venturi

and then through a check valve into the cabin. Adequate flow to maintain

pressurization up to the maximum differential pressure of 5.5 PSI is provided

by the engine at normal power setting. Power changes should be made

smoothly to prevent sudden changes in pressurization air inflow resulting in

cabin pressure transients.

Operation

The airplane may be operated in either the pressurized or depressurized mode.

The mode selection is made with the cabin pressurization switch, which either

activates the cabin control outflow valve or leaves it open. Mode operation

should be selected prior to takeoff. If a change from pressurized to

depressurized mode must be made while airborne, depressurize the cabin

following the procedure given below before turning the dump switch as

otherwise a rapid decompression occurs, which would cause discomfort to the

passengers. When changing from unpressurized to pressurized mode, the cabin

altitude rate of change will be limited by the pressurization controller. The

valves are also opened by the landing gear squat switch assuring depressurized

mode when aircraft is on ground to avoid bursting the cabin door due to cabin

pressure when opening.

In the pressurized mode cabin pressure is regulated by the cabin control

outflow valve allowing air to exhaust either to the pressure level preselected by

the cabin pressure controller or to maximum differential pressure level. Setting

the center dial (identified as “Flight Level”) of the cabin pressure controller

will suggest the system being at a certain flight altitude. So the system will

maintain the corresponding cabin altitude (about 5.5 PSI above static pressure

of flight level) or reach it with the rate set by the rate control knob located on

the lower left corner of the pressurization controller. Only in case of maximum

differential pressure is reached or flight level is below the selected cabin

altitude, cabin altitude changes with the same rate the flight altitude does.

In case of failure of the cabin outflow control valve the safety valve will open

at a differential pressure of slightly above 5.5 PSI to avoid structure damage.

Handling

Use the cabin pressure controller as follows. Also refer to the sample chart

(Figure 21-1).

Activate the pressurization controller by turning on the cabin pressurization

switch. Make sure the ENV AIR switch is ON.

Page 18 21

Page Date:

Set the published official airport altitude (such as shown on flight charts) under

the index arrow by turning the center control knob.

Turn the index arrow of the rate control knob (lower left corner of the control)

to the 12 o’clock position (approx. 500 fpm).

These steps set the system to pressurize at approximately 700 feet above the

runway after takeoff. The system will hold this cabin altitude until the

maximum differential altitude is reached (see “Cabin Altitude with minimum

Flight Level Setting” line of Figure 21-1) or a different cabin pressure is

selected.

After having cleared the airport area and established the climb and being on

course to the destination (see “a” on 0), select the flight level corresponding to

the intended cruise altitude in the center dial and align that with the index

arrow. This alignment also indicates the approximate cabin altitude (within

approx. 700 feet) at the index on the larger numbers marked “Airport Alt.”.

Increase or decrease the rate at which the cabin changes altitude for the best

comfort level from normally

500 fpm by turning the rate knob counter

clockwise for decreasing or clockwise for increasing the rate.

Usually it is the best method to set the rate to reach the changed cabin pressure

(referenced from the “Airport Alt.”) slightly ahead of reaching the cruising

altitude (550 fpm in the sample of Figure 21-1). This selected altitude will be

maintained until the aircraft changes altitude sufficiently to reach the max.

differential pressure or descends sufficiently to go below the selected airport

altitude.

When the aircraft reaches the proximity of the destination and starts to descent

(see “b” on 0), set the selector knob to the published airport altitude.

Set the rate so that the selected airport altitude is reached in the cabin prior to

descending to that altitude (650 fpm in the sample of Figure 21-1).

When approaching the runway, the pressurization will cease approximately 700

feet above the landing prior to landing. Should any slight pressure remain, the

remainder will dump when the squat switch closes. However, this is an

additionally safety device, because landing with cabin pressurized is not

allowed.

If pressurization mode shall be terminated during flight, follow the

CAUTION

procedure above, setting the airport altitude equal to the momentary flight

altitude. Do not switch to the depressurized mode before the selected

airport altitude has been reached.

Page Date:

21 Page 19

21-30-01

Cabin Outflow Control Valve Filter

Replacement

Detail Steps/Work Items

Key Items

Remove upper half of rear baggage

Machine screws AN 526

compartment wall.

10-32

Loosen the filter retention screw on the

It is not necessary to remove

control outflow valve housing until the filter

the screw entirely.

flange is free to rotate.

Rotate the filter until the flat on the filter

clears the screw head.

Remove the filter cartridge and replace with

new one.

Rotate the filter so filter flange is captured

by the screw head.

Tighten filter retaining screw.

21-30-02

Cabin Outflow Control Valve

The valve is attached to the LH side of the pressure dome.

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove upper half of rear baggage

Machine screws AN 526

compartment wall.

10-32

Remove tail cone access panel on LH

fuselage side.

Remove valve flange from pressure dome.

8 stop nuts MS 21044 AN3

with washers AN960 - 10L

(3/8 inch.)

Remove overflow tube.

9/16 fitting; retain with 11/16

wrench at pressure dome

fitting

Disconnect electrical connector.

Lift up valve from pressure dome

Install in reverse sequence of removal

Page Date:

21 Page 21

21-30-03

Safety Valve

The valve is attached to the RH side of the pressure dome.

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove upper half of rear baggage

Machine screws AN 526

compartment wall.

10-32

Remove tail cone access panel on LH

fuselage side.

Remove valve flange from pressure dome.

8 stop nuts MS 21044 AN3

with washers AN960 - 10L

(3/8 inch.)

Remove overflow tube.

9/16 fitting; retain with 11/16

wrench at pressure dome

fitting

Remove electrical connector

Lift up valve from pressure dome

Install in reverse sequence of removal

Observe the following hint

NOTE

Verify that blind plug at vacuum port is installed correctly. With

installed valve, the vacuum port is accessible behind the rear baggage

compartment wall.

Page 22 21

Page Date:

21-50-00

COOLING

Description

Refer to Figure 21-1.

The aircraft is standard equipped with an electrically driven vapor cycle air

conditioning system. The system consists of a compressor condenser module,

two evaporators and the switches in the CABIN section of the left side panel.

The electrically driven compressor condenser module is installed in the

unpressurized part of the tail cone aft of the rear pressure dome. Cooling air for

the condenser (circulated by the condenser fan) is taken from an inlet in the left

fuselage side aft of the cabin door and dumped overboard through an outlet on

the same side.

The cabin recirculation air is cooled by means of two evaporators. The front

evaporator is installed behind the co-pilot seat and the aft evaporator in the aft

pressure dome area. Condensation at the evaporators is drained by means of a

float type check valve for each evaporator.

The air condition system is activated by the AIR CON switch located in the left

side panel. The air-condition will only operate effectively with the cabin

blower VENT switch at least in LOW position.

The electric air-condition provides the ability to operate the system on ground

using ground power without the necessity to run the aircraft engine.

NOTE

It is not possible to operate the air condition on battery power as the high

current draw would shortly lead to a depleted battery. Therefore for

operation either the aircrafts generator (engine running) or a sufficient

external power source (capacity min. 100 A at 28 VDC) has to be

connected to the aircraft bus system. 125 A is recommended for maximum

cooling capacity. When using external power the battery must be off.

Service and Maintenance

Servicing of the air-conditioning unit shall be performed by an approved air-

conditioning service station; only R-134a type refrigerant must be used.

The air-conditioning compressor condenser module is equipped with

conventional evacuating and charging connections.

After new system plumbing installation, component replacement or line or

hose rupture, a leak check is required, see Enviro Systems General Operating,

Servicing and Maintenance Manual for Airborne R-134a Air-conditioning

Systems (LOAP 13) for leak check and general charging procedures.

Refer to this Manual also for component maintenance procedures.

Access to the compressor condenser module is gained through the tailcone

access hatch. Both low and high pressure service ports are located at this unit.

Charging quantity of the installation is 0.650 kg +/- 0.050 kg, proper charging

can be verified at the sight glass on the receiver dryer. With the system fully

charged and operating, observe the suction and discharge pressures. Typical

values at various ambient temperatures, with hot cabins are shown below:

Page Date:

21 Page 23

OAT

Suction pressure

Discharge pressure

(°C)

(psig)

112

133

156

180

21-50-01

Compressor/Condenser

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove tail cone access panel.

Refer to Chapter 51-00-01

Remove the refrigerant from the air

Refer to Enviro Systems

conditioning system

General Operating, Servicing

and Maintenance Manual for

Airborne R-134a Air-

conditioning Systems

(LOAP 13)

Remove all avionic boxes, which may block

XPDR, DME, amplifier

removal of compressor/condenser.

Remove refrigerant hoses.

Remove air hoses.

Remove compressor/condenser.

4 mounting screws

Reverse procedure for installation.

21-50-02

Evaporator

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove tail cone access panel.

Refer to Chapter 51-00-01

Remove the refrigerant from the air

Refer to Enviro Systems

conditioning system

General Operating, Servicing

and Maintenance Manual for

Airborne R-134a Air-

Page 24 21

Page Date:

Detail Steps/Work Items

Key Items

conditioning Systems

(LOAP 13)

4 (front

Set the co-pilot seat in the most forward

evaporator only)

position.

5 a (front

Remove side paneling.

Refer to Chapter 25-00-01

evaporator)

5 b (aft

Remove aft paneling.

Refer to Chapter 25-00-01

evaporator)

Remove refrigerant hoses.

Remove air hoses.

Cut electrical wires.

Reconnect later by splicing.

Remove mounting screws and remove

evaporator.

Reverse procedure for installation.

21-50-03

Soft Start Module

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove tail cone access panel.

Refer to Chapter 51-00-01

Disconnect 3 power lines.

Cut control line.

Reconnect later by splicing.

Remove soft start module.

4 mounting bolts

Install in reverse sequence of removal.

Ensure cable clamps are

installed.

Page Date:

21 Page 25

21-60-00

TEMPERATURE CONTROL

Description

Refer to Figure 21-1.

The system consists of a temperature controller, a cabin temperature sensor, a

duct temperature sensor, a temperature modulating valve, a temperature switch,

the BLEED OVERTEMP warning light and the TEMP CTRL switches and rheostat

on the left side panel.

With the ENV AIR switch ON environmental bleed air is provided for cabin

heating purposes. The bleed air, exiting the engine is too hot to be used for

cabin heating without prior cooling. The amount of cooling required is

dependent on ambient temperature, airspeed, engine power setting, desired

cabin temperature and adequate changes if these parameters change.

Cooling effectiveness is controlled by routing the environmental bleed air

through the air-to-air cooler or directly (bypass) to the cabin by means of the

temperature modulating valve. Operating mode of this valve is selected by the

controls grouped in the CABIN section of the left side panel. With the TEMP

CTRL switch being set to the AUTO position the computerized cabin

temperature controller compares the actual cabin temperature (measured by a

sensor in the cockpit ceiling) to the selected temperature. The temperature

controller is installed inside the cabin behind the side paneling between the

cabin door and the pilot’s seat. Selection is being done by means of the cabin

temperature rheostat also located in the left side panel CABIN section.

Adjustment range is between 13 °C and 30 °C (55 °F to 86 °F). Depending on

the difference between actual cabin temperature and selected cabin temperature

the controller determines a desirable cabin inflow temperature for the

environmental bleed air. The actual inflow temperature is measured by a sensor

located within the bleed ducting prior to cabin entry through the front pressure

bulkhead.

The temperature controller compares this actual inflow temperature to the

desired inflow temperature and adjusts the temperature modulating valve to

match this desired inflow temperature.

It is within the nature of this design (bleed air cooling by means of an air to air

heat exchanger) that cabin bleed air cannot be cooled below ambient

temperature before entering the cabin. Therefore a vapor cycle air conditioning

system (refer to Section 21-50) provides additional cooling capacity for hot

ambient conditions.

The automatic temperature control limits cabin inflow temperatures to values

below 72 °C. An additional independent thermal switch installed in the cabin

distribution valve activates the red BLEED OVERTEMP warning light located on

the annunciator panel in case the cabin inflow temperature exceeds 85 °C. In

case, the BLEED OVERTEMP warning light on the annunciator panel

illuminates, indicating a temperature controller failure, the temperature can be

manually controlled by switching the TEMP CTRL switch, to the MANUAL

position.

Page 26 21

Page Date:

Selected and held in COOL or WARM position activates the temperature

modulating valve manually (overrides the controller) causing warm up or cool

down of incoming bleed air.

21-60-01

Temperature Switch

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove RH IFD and RH part of main

Refer to Chapter 31

panel.

Remove attachment bolts of distribution

To allow moving the

valve.

distribution valve.

Move the distribution valve up some

centimeters.

Cut the electrical wiring from the

Reconnect later by splicing.

temperature switch

Remove temperature switch from the

distribution valve.

Install in reverse sequence of removal.

Function Test

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove RH IFD.

Refer to Chapter 31-60-01

Disconnect LH SCEET hose from the cabin

Worm drive hose clamp

distribution valve.

Place BATT switch to ON position.

Place NIGHT/DAY switch to TEST position.

To ensure annunciator lights

are OK.

Apply hot air to the temperature switch.

More than 85 °C.

Use a blow dryer.

Check BLEED OVERTEMP illuminates.

Replace temperature switch if

necessary.

Place BATT switch to OFF position.

Reinstall SCEET hose.

Page Date:

21 Page 27

Detail Steps/Work Items

Key Items

Reinstall RH IFD.

Refer to Chapter 31-60-01

Perform pitot/static test.

According to FAR 43,

Appendix E and AC 43.13-

1B CHG1 (or later) § 12-59

21-60-02

Duct Temperature Sensor

Removal/Installation

The duct temperature sensor is attached to the valve box on the RH upper

firewall with 4 bolts and nuts. To make the nuts accessible the forward hose

and the flange have to be removed.

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove LH and RH engine cowling.

Refer to Ch. 71-10-01/02

Disconnect the forward SCEET hose from

Worm drive hose clamp,

the valve box.

safety wire

Remove flange from the valve box.

4 nuts

Disconnect electrical connector from the

Bayonet nut

temperature sensor.

Remove temperature sensor.

4 bolts and nuts

Install in reverse sequence of removal.

Observe the following step.

Refer to Product Label and Material Safety Data Sheet for health and

WARNING

safety information before using PR812.

Seal flange with PR812.

21-60-03

Cabin Temperature Sensor

Removal/Installation

Detail Steps/Work Items

Key Items

Ensure BATT switch is OFF and no external

power connected.

Remove paneling above pilot seat.

Refer to Chapter 25

Disconnect electrical wiring from the cabin

temperature sensor.

Page 28 21

Page Date:

Table of Contents

22-00-00

GENERAL

22-10-00

AUTOPILOT

.................................................................................................... 6

Description.......................................................................................................... 6

Figure 22-1

Autopilot Installation

.......................................................................................... 8

System Components

........................................................................................... 9

Troubleshooting

Heading Calibration

22-10-01

Roll Servo

Removal

Figure 22-2

Roll Servo Installation

Installation

Function Test

22-10-02

Pitch Servo

Removal

Figure 22-3

Pitch Servo Installation

Installation

Function Test

22-10-03

Yaw Servo

Removal

Figure 22-4

Yaw Servo Installation

Installation

Function Test

22-10-04

Clutches (Pitch, Roll and Yaw Servo)

Torque Settings

Torque Adjustment

Figure 22-5

Clutch Torque Adjustment

22-10-05

Driving Wheels

Removal/Installation

22-10-06

Bridle Cables

Removal/Installation

Tension Settings

Tensioning

22-10-07

Cable Clamps

Figure 22-6

Cable Clamp Torquing

22-10-08

Trim Servo

Removal/ Installation

Function Test

22-10-09

Trim Servo Clutch

Torque Settings

Torque Adjustment

Page 2 22

22-10-10

Pressure Transducer

.......................................................................................29

Removal/Installation

.........................................................................................29

22-10-11

Yaw Amplifier

.................................................................................................30

Removal/Installation

.........................................................................................30

22-10-12

Programmer/Computer

..................................................................................30

Removal/Installation

.........................................................................................30

22-10-13

Turn Coordinator............................................................................................30

Removal/Installation

.........................................................................................30

22 Page 3

22-10-00

AUTOPILOT

Description

Refer to Figure 22-1. The S-TEC System 55X autopilot system is a rate based

autopilot. Internal signal processing for regulating purposes is mainly analog,

whereas digital electronics is used for the pilot interface and for controlling the

mode of operation.

Pitch and Roll Axis

The signal for the roll servo is generated using the following inputs:

Rate of turn information heading bug determined by the Turn Coordinator.

Navigation avionics (VOR / LOC, GPS; via IFD).

The signal for the pitch servo is generated using the following inputs:

Static pressure (via remote mounted Absolute Pressure Transducer).

Sensitive Accelerometer (contained in the Programmer / Computer unit).

Altitude Selector (via IFD, key pad or vertical speed knob on A/P computer).

Glide Slope Receiver (via IFD).

The autopilot can be activated by means of the

3-position AUTOPILOT

MASTER/FD switch located in the right lower side of the pilot's instrument

panel.

Switching it from the OFF-position to the first stage

(FD) energizes the

autopilot system. The autopilot will start its self-test routine ending up in a

ready mode if performed successfully. This allows the pilot to select the

different operating modes. If appropriate modes are activated set-point steering

commands are shown by the Flight Director symbol displayed in the LH IFD.

The pitch and roll servos are not engaged. Pitch and roll still have to be

controlled by normal steering, using the data provided by the IFD as a set-

actual comparison.

In the second stage (MASTER) the servos are energized and the autopilot

controls pitch and roll axis according to the operating mode(s) selected (refer to

POH).

One possibility to engage the autopilot (both axis) is given by the CWS switch

(control wheel steering) located on top of the right horn of the pilot's control

yoke. This mode engages the autopilot in a way which maintains the actual

pitch and roll attitude (refer to POH).

NOTE

Operation in a pitch mode is possible only if a roll mode is activated.

As a safety device an autopilot quick disconnect switch (AP DISC, red) is also

located in the left horn of the pilot's control wheel to enable the pilot to

disengage the autopilot quickly. Additionally, servo transmissions are designed

as slip clutches, which can be overpowered in any case of failure or

malfunction. The operation mode selection is done via the autopilot main unit

and the IFD or the related keyboard. Indication is made on the autopilot main

unit and the upper LH IFD.

Page 6 22

Trim System

The EXTRA 500 uses a tab at the elevator's trailing edge for pitch trim. This

tab is actuated by a Bowden cable with a special gear located in the horizontal

stabilizer transforming the long travel of the cable into the shorter travel finally

used for tab actuation. The Bowden cable itself may be actuated either by the

pilot using the trim wheel or by the trim servo located on the floor of the tail

cone compartment. The electric trim system may be operated independently

from the autopilot.

When an autopilot pitch mode is active and the electric trim system is switched

on by the TRIM master switch in the pilot's instrument panel, the trim system

operates in the auto trim mode. The pitch servo continuously senses the force

necessary to maintain the assigned pitch attitude and transmits the signal to the

autopilot main unit. This computes a signal to actuate the trim servo. By this

mechanism the force the pitch servo has to apply on the elevator is minimized.

When the autopilot is active (in a pitch mode) and the electric trim servo (TRIM

master switch) is switched off a visual and audible annunciation to the pilot is

provided by the autopilot system asking him to trim the airplane manually by

means of the trim wheel.

With autopilot switched off or no pitch mode engaged, but electric trim servo

(TRIM master switch) on, the longitudinal trim may be adjusted by the pilot

using the momentary split rocker switch on top of the left horn of the pilot's

control yoke.

Yaw Damper

The yaw damper system consists of two units, the yaw servo actuating the

rudder control cables and the yaw amplifier, which generates the signal for the

servo. The amplifier is installed behind the aft pressure dome in the tail cone

compartment. The amplifier features an integrated lateral acceleration sensor.

This sensor detects lateral components of the gravity vector, which corresponds

to the “ball not being centered”. Based on this input signal the yaw amplifier

derives the control signal for the yaw servo.

To allow for a fine adjustment of slip/skid angle, a yaw trim potentiometer

allows the pilot to adjust (“trim”) the zero yaw angle based on a slip/skid

indicator.

In the OFF position of the yaw damper control switch the yaw damper is not

engaged and the yaw servo clutch remains open. With the switch in ON

position the yaw damper remains engaged as long as the autopilot is engaged in

a roll mode. A roll signal from the autopilot main unit is provided to the yaw

amplifier as an additional input (to the lateral acceleration sensed internally).

Yaw damper disconnect is provided by the same means as the autopilot

disconnect as the autopilot main unit provides a yaw damper enable signal to

the yaw amplifier as long a roll mode is active. As soon as the autopilot

disconnects the yaw damper follows therefore.

22 Page 7

System Components

The following components are used in the S-TEC 55 installation of the

EXTRA 500:

Unit Designation

Location

Function

Autopilot Components

Programmer/Computer

Instr. Panel

Pilot interface

(P/C)

signal generation for roll, pitch and pitch

(special configuration for

trim servo

EXTRA 500)

Yaw amplifier

Tail cone equipment

Yaw sensor & signal generation for yaw

rack

servo

Turn Coordinator

Instr. Panel

Sensing rate of turn,

input signal for P/C,

indication to pilot

Absolute pressure Transducer

Tail cone equipment

Converting static pressure => electric signal

rack

Roll Servo

Front wing

Aileron actuation

compartment

Pitch Servo

Tail cone equipment

Elevator actuation, force sensing for trim

rack

system

Pitch Trim Servo

Tail cone floor

Trim tab actuation

Yaw Servo

Tail cone equipment

Rudder actuation

rack

Autopilot Relay

behind instrument

Connecting inputs to A/P computer from

panel

either IFD 1 or IFD 2

Autopilot Master Switch

Autopilot Panel

Activation of autopilot and / or flight

(Pilot Instrument

director

Panel)

Pitch Trim Switch

Autopilot Panel

Activation of electric pitch trim System

(Pilot Instrument

Panel)

Yaw Damper Master Switch

Autopilot Panel

Activation of yaw damper

(Pilot Instrument

Panel)

Yaw Trim Knob (rotary

Autopilot Panel

Adjustment of zero jaw attitude

Potentiometer)

(Pilot Instrument

Panel)

Trim command Switch

Control Wheel

Change of aircraft pitch trim

(split switch)

CWS-Switch

Control Wheel

Engaging CWS-mode

Autopilot disconnect / trim

Control Wheel

Disengaging autopilot, interruption of

interrupt switch

electric trim actuation

22 Page 9

Troubleshooting

Complaint

Possible Cause

Remedy

Autopilot will not engage in

Autopilot has no power

Check AUTOPILOT MASTER

any mode

switch FD or MASTER.

Autopilot has no power

Check AVIONICS switch ON.

No valid signals from turn

Check turn coordinator no

coordinator

flag.

AP disconnect switch

Check AP disconnect switch

struck/defective

continuity.

Pitch trim switch

Check pitch trim switch stuck.

stuck/defective

Computer defective

Replace computer.

Will not engage in any altitude

No roll mode engaged

A roll mode MUST be

mode

selected first

Computer defective

Replace computer.

No valid signal from absolute

Replace absolute pressure

pressure transducer

transducer.

CWS does not work

Autopilot not coupled in both

An altitude and roll mode

axes

must be engaged previously.

Switch defective

Replace CWS switch.

Computer defective

Replace computer.

AP disconnect switch does not

Switch defective

Replace AP disconnect switch.

work

Computer defective

Replace computer.

Mode engages, but servo does

AP in FD mode

Check AUTOPILOT MASTER

not couple

switch in MASTER position

(not FD)

Servo defective

Replace servo.

Electrical Pitch trim does not

Pitch system has no power

Check battery bus power.

work

Pitch system has no power

Check pitch trim switch ON.

Pitch trim switch defective

Replace pitch trim switch.

Computer defective

Replace computer.

Pitch trim servo defective

Replace pitch trim servo.

22 Page 11

Complaint

Possible Cause

Remedy

Yaw trim does not work

No power to yaw amplifier

Check battery bus power

YAW DAMPER switch OFF.

YAW DAMPER switch ON.

Yaw damper switch defective

Replace yaw damper switch.

No roll mode enabled

Engage roll mode first.

Yaw amplifier defective

Replace yaw amplifier.

Yaw servo defective

Replace yaw servo.

Yaw trim poti defective

Replace yaw trim

potentiometer.

Heading Calibration

Detail Steps/Work Items

Key Items

Attach external power.

Check all switches OFF,

A/P CMPTR CB IN,

Turn-Coord CB IN,

A/P SERVO CB IN,

All IFD CB-s IN

Switch on EXT PWR

Switch on AUTOPILOT - MASTER

Check turn coordinator runs up,

off-flag disappears,

Autopilot display shows 7 on display,

Autopilot display shows rdy,

LH IFD shows AP RDY

Wait for 2 minutes

to let turn coordinator run up

Set IFD to NAV I

Tune NAV I to a frequency that has no

reception

Set heading bug to current heading

push heading knob on keypad

Select NAV mode on autopilot

Adjust the potentiometer between the REV

use miniature flat screwdriver

and ALT buttons in small increments until

the yoke stops turning

Make sure in the end the AP is in SOFT

indicated on IFD

mode

Page 12 22

Extra 500. Maintenance Manual (2012) - page 5