GE Druck ADTS 405 User manual

Druck ADTS 405/405F
Air Data Test Systems
Service Manual K0171
GE
Sensing & Inspection Technologies
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© 2008 General Electric Company. All rights reserved.

Druck ADTS 405 Service Manual
K171 Issue No. 1 Page i
TABLE OF CONTENTS
Preliminary pages
Table of contents (this table)
Introduction
Purpose
Scope
Glossary
Abbreviations
Chapter
1 DESCRIPTION
2 DISMANTLING
3 ASSEMBLING
4 TESTING
5 CALIBRATION
6 ILLUSTRATED PARTS LIST

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K171 Issue No. 1 Page ii
Associated Druck Documents:
K114 - ADTS 405 User Manual
INTRODUCTION
Purpose
This technical manual provides servicing instructions and a parts list to an intermediate level of
maintenance for the Druck ADTS 405 series of air data test systems.
Scope
This technical manual contains a constructional description, a functional description explaining the
theory of operation, dismantling, assembling and testing procedures. The test equipment and special
tools required for the recommended maintenance level are listed.

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K171 Issue No. 1 Page iii
GLOSSARY
Terminology
The terminology used in this manual is specific and individual interpretation must not be
introduced. The terms are defined as follows:
Adjust:
To bring to a more satisfactory state; to manipulate controls, levers, linkages, etc. to return
equipment from an out-of-tolerance condition to an in-tolerance condition.
Align:
To bring into line; to line up; to bring into precise adjustment, correct relative position or
coincidence.
Assemble:
To fit and secure together the several parts of; to make or form by combining parts.
Calibrate:
To determine accuracy, deviation or variation by special measurement or by comparison with a
standard.
Check:
Make a comparison of a measure of time, pressure, temperature, resistance, dimension or other
quality with a known figure for that measurement.
Disconnect:
To detach the connection between; to separate keyed or matched equipment parts.
Dismantle:
To take apart to the level of the next smaller unit or down to all removable parts.
Ensure:
To confirm that a proper condition exists; to find out with certainty.
Examine:
To perform a critical visual observation or check for specific conditions; to test the condition of.
Fit:
Correctly attach one item to another.
Inspect:
Review the work carried out by Specialists to ensure it has been performed satisfactorily.
Install:
To perform operations necessary to properly fit an equipment unit into the next larger assembly
or system.
Maintain:
To hold or keep in any particular state or condition especially in a state of efficiency or validity.
Operate:
Ensure that an item or system functions correctly as far as possible without the use of test
equipment or reference to measurement.
Readjust:
To adjust again; to move back to a specified condition; to bring back to an in-tolerance condition.
Reconnect:
To rejoin or refasten that which has been separated.
Refit:
Fit an item which has previously been removed.

Druck ADTS 405 Service Manual
K171 Issue No. 1 Page iv
Terminology (continued)
Remove:
To perform operations necessary to take an equipment unit out of the next larger assembly or
system. To take off or eliminate. To take or move away.
Repair:
To restore damaged, worn out or malfunctioning equipment to a serviceable, usable or operable
condition.
Replace:
Remove an item and fit a new or a serviced item.
Reset:
To put back into a desired position, adjustment or condition.
Service:
To perform such operations as cleaning, lubricating and replenishing to prepare for use.
Test:
Ascertain by using the appropriate test equipment that a component or system functions
correctly.

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K171 Issue No. 1 Page v
Abbreviations
The following abbreviations are used in this manual; the abbreviations are the same in the singular
and plural.
A Ampere
abs Absolute
a.c. Alternating current
ALT Altitude
CAS Calibrated airspeed
d.c. Direct current
e.g. For example
EOC End of conversion
EPR Engine pressure ratio
EPROM Electrically programmable read only memory
etc. And so on
Fig. Figure
ft Foot
g Gauge
Hg Mercury
Hz Hertz
IAS Indicated airspeed
i.e. That is
IEEE 488 Institute of Electrical and Electronic Engineers standard 488 data
in Inch
kg Kilogram
LED Light emitting diode
(M) Magnesium alloy
m Metre
mA Milliampere
max Maximum
mbar Millibar
min Minute or minimum
mm Millimetre
mV Millivolts
No. Number
N.m. Newton metre
Para. Paragraph
Ps Static pressure
psi Pounds per square inch
Pt Total pressure
Qc Differential pressure Ps/Pt
QFE Local atmospheric pressure
QNH Barometric pressure at sea level
ROC Rate of climb
SCPI Standard commands for programmable instruments
TAS True airspeed
TE Test equipment
V Volts
Vc Calibrated velocity
Vt True velocity
+ve Positive
-ve Negative
°C Degrees Celsius

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K171 Issue No. 1 Page vi

Druck ADTS 405 Service Manual
K171 Issue No. 1 Page 1-1
Chapter 1
Description
CONTENTS
Para.
Introduction.........................................................................................1
SPECIFICATION
DESCRIPTION
ADTS 405 and Electronics Rack (ADTS 405F) .......................5
Pitot and Static Controllers ..........................................................11
Operation ................................................................................14
Pressure output ....................................................................19
Soft start ..................................................................................21
Control computer and communications ...............................22
ARINC 429 Interface (special order) .........................................23
Altimeter Encoder Interface (special order)..........................24
IEEE 488 Interface (option E) .... 25
Pump Rack...........................................................................................26
Hand terminal ....................................................................................31
Illustrations
fig.
ADTS 405 General view .................................................................1-1
ADTS 405F General view ...............................................................1-2
ADTS 405 ..............................................................................................1-3
ADTS 405F Racks ..............................................................................1-4
ADTS 405 and Electronics Rack Internal view.....................1-5
Controller PCB Schematic.............................................................1-6
Ps Manifold Schematic...................................................................1-7
Pt Manifold Schematic ...................................................................1-8
Supervisor Computer and Communications .......................1-9
Pump Rack...........................................................................................1-10
Hand terminal ....................................................................................1-11

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INTRODUCTION
1. There are two versions of the ADTS 405 a 19", 6U high (10½”) rack-mounted unit and a flight line
unit. The ADTS 405 is a rack-mounted system and, with external pressure and vacuum supplies
connected, provides measurement and control for sense and leak testing and functional tests of air
data instruments, components and systems. The ADTS 405F is a self-contained air data test system
providing complete pressure and vacuum measuring and control for on-aircraft sense and leak testing
and functional tests of air data instruments, components and systems. The unit comprises an
electronics rack and pump rack enclosed in a high density, polyethylene case.
2. The user interface for the rack-mounted version is a front panel keyboard and display with a
hand terminal as an option. For the ADTS 405F version the hand terminal is the supplied user interface
with the front panel keypad and display as an option. The ADTS 405 can also be controlled by a
computer (PC) using the front or rear panel IEEE 488 communications interface. The front panel
contains the operate switch and the mimic panel with LED indicators showing the operation of the two
pneumatic channels.
3. The pump rack, on the ADTS 405F, produces pressure and vacuum supplies for the electronics
rack and for external connectors. Located on the front panel, the external connectors provide for
external pressure and vacuum supplies (EXT PRESSURE and EXT VACUUM) and an auxiliary static
(vacuum) output (AUX). The auxiliary static output provides vacuum for suction-type static adaptors.
The rack is cooled by a fan located under a protective cover on the front panel. The power supply
connection for the ADTS 405F is located on the front panel.
4. The ADTS 405 can display and operate in either units of pressure measurement or aeronautical
units. The rate that the pressure changes to a new set-point can be set. The rate is then reduced as
the set-point is achieved and maintained, without overshoot. A `ground' facility automatically and
safely controls both channels to atmospheric pressure at the previously entered rates of change and
then informs the user when both channels are safely at `ground'.

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Figure 1-2 General view
Figure 1-1 General view

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SPECIFICATION
Electrical power supply ......................................................................................................................................... 88 to 260V a.c.
........................................................................................................................................................ 47 to 440Hz
ADTS 405 ........................................................................................................................ 200 VA maximum
ADTS 405F........................................................................................................................500VA maximum
Pneumatic outputs
Altitude range .........................................................................................................................................-2000ft to +80000ft
Altitude accuracy
Sea level ................................................................................................................................................................... ± 5ft
30,000ft ....... ............................................................................................................................................................ ± 7ft
60,000ft .................................................................................................................................................................. ± 25ft
Static
range ...................................................................................................................................... 1355 to 35 mbar abs
accuracy....................................................................................................................................... ± 0,012% reading
............................................................................................................................................................ 0.008% FS
Airspeed ranges
civil ............................................................................................................................................ 0 to 500 knots
military .................................................................................................................................... 0 to 850 knots
special................................................................................................................................... 0 to 1000 knots
Airspeed accuracy
50 knots ...................................................................................................................................................... ± 0,5 knots
500 knots ................................................................................................................................................. ± 0,07 knots
Qc
range ...................................................................................................................................... 35 to 2700 mbar abs
accuracy....................................................................................................................................... ± 0,015% reading
............................................................................................................................................................ 0.007% FS
Special
range ...................................................................................................................................... 35 to 3500 mbar abs
accuracy....................................................................................................................................... ± 0,015% reading
............................................................................................................................................................ 0.007% FS
Mach number
civil ........................................................................................................................................................ 0 to 1,00
military ................................................................................................................................................ 0 to 6,00
Accuracy ....................................................................................................................................... Better than 0,005
Rate of climb
Generated ranges
civil ........................................................................................................................................ 0 to 6000 ft/min
military ............................................................................................................................. 0 to 15000 ft/min
Accuracy ................................................................................................................................................ ±1% of value
Dimensions
ADTS 405 ............................................................................................................. 485 mm x 270 mm x 305 mm
Weight .................................................................................................................................................................... 12 kg
ADTS 405F .......................................................................................................... 442 mm x 755 mm x 332 mm
Weight .................................................................................................................................................................... 29 kg
Temperature
Operating ............................................................................................................................................... 10°to +50°C
Calibrated ................................................................................................................................................. 5°to +35°C
Storage.................................................................................................................................................. -40°to +70°C
Note: The rates, ranges and limits may be different depending on customer requirements.

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K171 Issue No. 1 Page 1-5
Figure 1-3 ADTS 405
LN

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Figure 1-4 ADTS 405F Racks
Electronics Rack Pump Rack
Case

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K171 Issue No. 1 Page 1-7
Figure 1-5 ADTS 405 and Electronics rack Internal view
Description
ADTS 405 and Electronics rack (ADTS 405F)
5. The unit contains the pitot and static manifolds, together with all appropriate solenoid valves,
pressure transducers and pneumatic output connectors. Also located in this rack are the controller
PCB for each channel, computer PCB, IEEE 488 PCB key-pad and display PCB, ARINC 429 PCB and a
power supply unit.
PSU
Manifold
Control
computer
PCB
IEEE 488
PCB
Controller PCB (Ps)
Pressure input
connection
Humidity
sensor
cable
Vacuum input
connection
printer
connection
IEEE 488
connection
Pressure
regulator

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Power supply
6. The power supply unit is located in the electronics rack enclosed in a metal casing. Output from
the PSU supplies the rack with a nominal +5V and ±15V and a semi-regulated 24V supply (regulated
with respect to +5V supply). The circuit automatically resets after an interruption caused by a power
failure.
Solenoid valves
7. All solenoid valves are of a similar type, spring-loaded to the de-energised condition. When
energised, the plunger moves against spring pressure to operate the valve. The principal valves are the
apply and release solenoids, these operate alternately to connect the manifold either to the pressure or
the vacuum connection from the pump generating and then holding the required pressure in the
manifold. The relative opening times of the two valves are determined by the error signal in the
controller PCB, thereby ensuring that the pressure in each manifold reaches an equilibrium at the
pressures appropriate to the altitude, speed, rate of climb or engine intake condition demanded at the
hand terminal. The valves also equalise air pressure to give a zero reading during a self-test routine
when the test system is isolated from the aircraft air data systems. Both channels have protection
valves controlled by the microcomputer, when energised the valves close isolating the test system
from the aircraft system.
8. The humidity sensors measure the humidity of the air for each manifold producing a voltage
signal proportional to the humidity. The voltage is amplified and corrected using stored calibration
data held in each controller circuit. The resulting voltage is used to correct the signal from the vibrating
cylinder pressure transducer.
9. The pressure input line is fitted with a filter and a 9 bar pressure regulator before it feeds the
manifold assembly. The vacuum input line also has a filter.
10. The principal components of the manifold assembly are two pneumatic manifolds (one for pitot
connection, one for static), together with their associated solenoids, pressure sensing transducers.
These components are mounted on the inside of the rack and are not accessible when the rack is
installed.

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Pitot and Static Controllers
11. The controller PCB is a self-contained pressure measurement control system which takes the
analogue set-point from the data converter and compares it with the voltage from the transducer. A
difference (error) is used to generate the pulse width modulated drive voltages for the ‘apply’ and
‘release’ solenoid valves which determine the pressure in the manifolds. Both controllers operate in a
similar way with additional configuration held in EEPROM.
12. The controllers receive pressure and pressure rate commands over the internal communications
ring and convert them into controlled pressure and pressure rates at the output using the rough
vacuum and pressure supplied by the pump unit. They accurately measure the pressure and pressure
rate at the output and transmit it over the communications ring the control computer.
13. Other commands can be used to open and close auxiliary solenoid valves, switch the controller
on and off (measure mode), hold the changing control pressure and oscillate around the set-point. Any
errors detected during internal self-test and during normal operations will be coded and transmitted on
the internal communications ring.
Operation
14. If the controller is on, a pressure and pressure rate demand received is processed by the
microcomputer and output via the set-point generator (digital to analogue convertor) as an analogue
voltage which forms the inner loop set-point. The inner loop is a high bandwidth analogue closed loop
pressure control system. The inner loop maintains a pressure in the manifold which at all times closely
follows the inner loop set-point.
Inner loop
15. The pressure in the manifold is measured by the control transducer which is a silicon strain-
gauge pressure transducer giving a voltage output proportional to the pressure applied. This voltage is
amplified by the signal conditioning circuits, given further gain depending on the mode of operation by
the gain switching circuits and then subtracted from the inner loop set-point and amplified in the error
amplifier. The resulting error signal is frequency compensated to keep the inner control loop stable,
then applied to a pulse generator circuit that produces a pulse width modulated output, through a
power driver circuit, to both the vacuum and pressure solenoids.
Outer loop
16. As the pressure changes in the manifold the pressure approaches the set-point the outer loop
starts operating. The pressure in the manifold is first measured by the main transducer. This is a
vibrating cylinder pressure transducer producing a high stability, high accuracy frequency (square
wave) proportional to pressure and an analogue voltage proportional to temperature.
17. The pressure signal feeds a 24 bit period counter which counts a 20 MHz reference oscillator for
a number of cycles of the incoming square wave representing pressure. This enables the incoming
square wave to be measured to a very high resolution by the microcomputer. The microcomputer
software uses the pressure and temperature data to calculate the exact pressure being applied to the
main transducer. Further corrections are made by the microcomputer using the stored zero and span
constants from the controller module and the stored constants for the humidity sensor.
18. The resulting accurate pressure reading is amplified and frequency compensated by the
microcomputer and, after subtracting the entered aim point, the resulting value is sent to the set-point
generator (DAC) to generate the inner loop set-point. This causes the manifold pressure to change
until the pressure measured by the main transducer is exactly the same as the pressure demand sent
by the hand terminal.

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Figure 1-6 Controller PCB Schematic
Figure 1-7 Ps Manifold Schematic

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Pressure output
19. The pressure generated in the manifold can be applied to the aircraft system by opening the
output solenoid. The command to open the output solenoid is received over the internal
communication ring. A signal is sent to the auxiliary drivers but the output solenoid will only open if the
ready line is active.
Ready line
20. The ready line must be in an active state to enable the auxiliary solenoid driver circuits. The ready
line is deactivated by an interruption of this line or by a fault detected by the watchdog timer and fail
safe circuitry. Under fault conditions the output valve instantly closes isolating the output from the
aircraft systems.
Soft start (Fig 1-7)
21. This provides an almost instantaneous transition from measure mode to control mode. When
the controller is off the switch is in the measure position, connecting amplifier A across the input and
output of the frequency compensation circuit. The output of the frequency compensation circuit is
forced to zero ensuring that no pulses will be applied to the pressure and vacuum valves when the
controller is switched on. When the controller is selected on, the set-point generator is adjusted until
the voltage at the output of the error amplifier is the same as the voltage applied to the frequency
compensation circuit by amplifier A. With equal voltage applied, the switch changes from measure to
control, disconnecting amplifier A and, amplifier B initiates the soft start signal to microcomputer which
switches on the controller. The value of the set-point is sent back to the microcomputer where it is
converted to current units of display and used as the current aim value. It takes less than 2 seconds for
the controller to come on-line.
Figure 1-8 Pt Controller PCB Schematic

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K171 Issue No. 1 Page 1-12
Figure 1-9 Supervisor Computer and Communications
Supervisor Computer and Communications
22. The supervisor computer consists of the computer PCB located on a motherboard. The computer
PCB is a self-contained microcomputer based on the 68000 microprocessor. The software is contained
in two EPROM located on the computer PCB. The computer PCB provides direct communication with
the hand terminal and an internal communications ring in the form of RS422 differential drivers and
receivers. It also provides a direct interface for the Centronics parallel printer output connector on the
front panel.
The motherboard distributes the data, address and control bus to the control computer. It also
contains a ready line interface and EEPROM for storing system configuration information and test
program sequences.