HR Smith Techtest 503 Series User manual

MAINTENANCE MANUAL
FOR
EMERGENCY LOCATOR TRANSMITTER
TYPE 503 SERIES
Issue 17 - 11.04.18
CN 10407
HRS1013-04-02
Commercial In Condence
Techtest
Limited
Street Court
Kingsland, Leominster
Herefordshire HR6 9QA, England
Telephone:[phone]
E-mail:[e-mail]
Fax: [phone]
www.hr-smith.com
Emergency
Location
and Rescue
Equipment

Commercial In Condence
Issue 17 - 11.04.18 - CN 10407
HRS1013-04-02 1
Preface
This manual is a controlled document, and as such is subject to amendment. It is in the interest of
the user to register this manual with Techtest Limited to ensure receipt of any amendments.
Amendments subsequent to the Initial Issue will bear the number of the amendment with which
it was issued. Changes of technical import within each new or revised leaf will be identied by a
marginal indicator. Such indicators will be omitted when the leaf is next re-issued. When the whole
of the chapter is so changed or reorientated that the inclusion of amendment indicators would be
impracticable, the words “(Completely Revised)” will appear at the head of the relevant chapter.
Any queries regarding this manual should be addressed to:
Product Support
Techtest Limited
Street Court
Kingsland
Leominster
Herefordshire
HR6 9QA
U.K.
Tel. [phone]
Fax. [phone]
Email: [email protected]

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Amendments Record
Issue number Changed by Date/ C/N Reference Pages Affected
FOR PREVIOUS ISUES REFER TO ARCHIVES
13 S. Prescott 21.05.15/ CN TT7120 13 & 14 Drawings updated
14 S. Prescott 31.05.16/ CN 10146 9
15 S. Prescott 21.03.17/ CN 11100 7
16 S. Prescott 16.01.18/ CN 11821 9
17 S. Prescott 11.04.18/ CN 10407 5

Commercial In Condence
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HRS1013-04-02
- CONTENTS -
PAGE
Preface 1
Contents 3
SECTION
1. SYSTEM DESCRIPTION 5
2. LINE REPLACEMENT UNITS (LRUs) 5
2.1 Emergency Locator Transmitter 5
2.2 G-Switch 6
2.3 Remote Controller 6
2.4 Mounting Rack 6
2.5 Interface Unit 7
2.6 Water Activated Switch 7
2.7 Antenna 7
3. ELT INHIBIT FACILITY 7
3.1 Inhibit Facility 7
3.2 Inhibit Connection 8
4. SERVICING 8
4.1 Physical Inspection 8
4.2 Battery Replacement 8
4.3 Troubleshooting 8
4.4 Diagnose Mode 8
4.5 Repair 9
4.6 Antenna 9
4.7 Operation 9
5. RECHARGING & CONDITIONING THE G-SWITCH BATTERY PACK 9
5.1 Testing the Battery Pack 10
6. ILLUSTRATED PARTS 11
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1. SYSTEM DESCRIPTION
The Techtest Limited 503 Series of Emergency Locator Transmitter (ELT) is a battery
powered unit that on activation, provides full emergency frequency operation at 121.5 MHz,
243.0 MHz and 406.025 MHz.
The 503 ELT can be used as a xed or xed/ portable system, with options of two or three axis
G-Switch units for automatic activation of the beacon should the aircrew not have activated
the beacon prior to the emergency. The system can include an interface unit, which is
designed to update the 406.025 MHz transmission with the latest onboard positional data.
The Remote Controller for the ELT system makes it possible to test and operate the ELT
from the aircrew positions and an in-built sounder and lamp indicates the system status.
An external antenna is mounted on the airframe in a position most likely to survive an
accident.
The Water Activated Switch provides the ELT with automatic activation upon immersion in
salt or fresh water.
By design the 503 ELT system is modular in construction and a number of congurations
can be assembled.
This manual covers the system module by module and then comments on the various
congurations. The reader has to select the sections of this manual that are relevant to the
particular installation on the aircraft.
The COSPAS-SARSAT message programmed is determined by the COSPAS-SARSAT
authority of the country where the ELT is to be registered. It should be noted however,
that a USER-LOCATION protocol message only encodes positional information with a
resolution of 4 minutes. The NATIONAL-LOCATION and STANDARD-LOCATION protocol
message formats encode positional information with a resolution of 4 seconds. It is strongly
recommended for systems that include positional information (GPS), a STANDARD-
LOCATION or a NATIONAL-LOCATION protocol message is chosen.
winBeacon (QA-00-120) is a software package supplied by Techtest that can be used to
Encode or Decode COSPAS-SARSAT messages. This is a stand-alone package that does
not connect to any hardware.
2. LINE REPLACEMENT UNITS (LRU’s)
2.1 ELT 503-1 (Figure 1)
The ELT is manufactured in high visibility yellow thermoplastic. It is self contained
and has its own long life battery, control switch and antenna port.
The battery (A0673-1) has an installed unused life of 5 years and will always provide,
as a minimum, 24 hours use at 406.025 MHz (5 watts) and 48 hours use at 121.5
MHz and 243.0 MHz (0.1 watts).
The 503-1 forms the basic transmitting unit which, in the portable mode, can be
operated as a stand alone unit provided that an antenna is connected.
The battery can be changed without the use of tools by simply depressing two locks,
one either side of the unit, with nger pressure and simultaneously sliding the battery
out. Replacement batteries are simply slid into position and the locks engaged.
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2.2 G-Switch 503-7 Series, 503-19 Series, 503-35 Series & 503-36 Series
(Figures 2 & 3)
The G-Switch forms an essential part of the xed ELT system.Dependant upon
the model in the particular system, the G-Switch triggers the ELT into transmission
when the ‘G’ force exceeds a preset limit in TWO or THREE
bidirectional axis. The G-Switch is always installed along with the ELT and is
connected via the 9 pin connector.
2.3 Remote Controller 503-4, 503-17, 503-20, 503-52 & 503-53 (Figures 4 & 5)
The Remote Controller is a small switch unit from which the aircrew can test / reset
the ELT, or switch it ON in an emergency, before the G-Switch automatically activates
the system.
The front panel has an indicator lamp and the unit has a sounder inside which gives
an audible tone.
The 503-52 Remote Controller is the same as the 503-20 but is mounted vertically
2.3.1 AF/AP ELT Cockpit Control Panel 503-51 (Figure 6)
The AF/AP Cockpit Control Panel has similar functions to the 503-20 but
with an additional Fault indicator and Inhibit switch.
2.4 Mounting Rack A0637 Series
To be effective the G-Switch has to be mounted to coincide with the expected ‘G’
forces in any accident. It is therefore necessary to mount the G-Switch to the
airframe in the correct attitude and ensure that the ELT is permanently connected to
the G-Switch.
The mounting rack will be positioned to best withstand high ‘G’ loading in the event
of an emergency and may not be readily located.
2.4.1 Fixed Mounting Tray (Figure 7)
The Fixed Mounting Tray is secured to the airframe by the four Dzus fasteners
or four xing screws.
2.4.2 Fixed / Portable Tray (Figures 8 & 9)
The Fixed / Portable Tray is secured to the airframe by six xing screws
except for Figure 9 which has nine xing screws. The ELT can, as required,
be withdrawn from the rack. In the installed position the G-Switch, which
is pre-installed into the rack, is coupled to the ELT and has an RF lead to the
antenna.
Should the ELT be required as a stand alone unit the antenna lead is
disconnected, the toggle clip is lifted and the ELT withdrawn from the rack.
A portable antenna is provided and is stowed along the top of the ELT rack,
this should be removed and tted to the ELT. The ELT can then be switched
on and used as a portable ELT unit.
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2.5 Interface Unit 503-15 Series (Figure 10)
The Interface Unit is designed to pass GPS data to the ELT such that the 406.025 MHz
transmission can pass positional data to the satellite. The Interface Unit can be JAA
(ED62) compatible or FAA (RTC/DO-204) compatible in order to provide the required
interface. The change is a link in the interface connector and is not switchable by the
operator.
2.6 Water Activated Switch 503-23-1 (Figure 11)
The Water Activated Switch provides the ELT system with automatic activation upon
immersion in salt or fresh water.
2.7 Antenna (Figures 12 - 19)
External to the aircraft a three frequency antenna transmits the signal. The antenna
can be anyone of the antenna types shown in Figures 12 to 18. The antenna shown
in Figure 19 is used when the ELT is operated in the portable mode. This antenna is
stowed ready for use on the mounting tray.
3. ELT INHIBIT FACILITY
Note: This section applies only to the G-Switch variants incorporating an inhibit
facility.
These variants are:
503-7-3, 503-7-3INH, 503-7-4, 503-7-12INH, 503-7-14,
503-19-1, 503-19-2, 503-19-2A, 503-19-4,
503-19-5, 503-19-7, 503-19-8, 503-19-10, 503-19-11, 503-19-12,
503-35, 503-35-1, 503-35A, 503-35AA, 503-35-AM & 503-35A-AM
For all other G-Switch variants, Pins 10, 11 & 12 on the G-Switch should not be
connected.
The ON position of the ARM/OFF/ON switch on the G-Switch over-rides all the other
inputs:
It by-passes all other inputs including ‘INHIBIT’.•
It does not carry out a BIT.•
It does not wait for GPS and therefore does not encode a GPS position.•
It activates the ELT immediately.•
It is effectively an ‘OVERRIDE’ switch.
In normal operation it is not envisaged that this switch would be used. The ON switch on
the remote control panel would be used instead (As part of ED62, the ARM/OFF/ON switch
should not be accessible from the pilot’s seated position)
3.1 Inhibit Facility
The Inhibit Facility (where incorporated) allows the installation of a separate switch
to disable (inhibit) the operation of the G-Switch. When inhibited, the ELT cannot be
activated due to ‘G’ levels or by selecting ‘ON’ at the Remote Controller. The self test
function is also disabled. The system can, however, be activated by the ARM/OFF/
ON switch on the G-Switch.

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3.2 Inhibit Connection
To inhibit the ELT system, Pins 10, 11 or 12 on the G-Switch are connected to ground
(aircraft chassis). This is achieved via a separate switch, available on the 503-51,
which allows the inhibit function or normal operation to be selected.
4. SERVICING
The sealed for life construction, and Built in Testing, limits the servicing that is required, or
necessary, to maintain the beacon in a fully serviceable state.
The periodicity of servicing set out below is a recommendation and can be varied to suit
the type of operational use and operating conditions.
4.1 Physical Inspection
It is recommended that the ELT system is inspected for damage at the following
periodicity.
Antenna - Daily
Control Unit - Monthly
Emergency Locator Beacon - 3 months
4.2 Battery Replacement
The ELT battery must be changed every 5 years or sooner, if the ELT has been
used for any other purpose than the Built in Test.
The G-Switch battery must be changed every 2.5 years, and has a storage life of 5
years.
4.3. Troubleshooting
The ELT system consists of a sealed for life ELT beacon complete with battery.
An additional G-Switch and remote controller switch are included to enable the ELT
to be switched to ON either on impact or by the aircrew.
Since the ELT has an in built test system and the test function can be activated at
the ELT and at either of the two switches, the system can be tested.
A test failure at the remote control switch indicates a switch failure, a G-Switch
failure, a wiring failure or an ELT failure. A test at the ELT beacon will indicate the
status of the beacon. If a fail then replace the beacon, if a pass then test the switch
and wiring loom.
A test failure from the G-Switch test switch shows the fault condition to be in the
G-Switch or ELT.
A test at the ELT will indicate pass or fail. Fail will indicate a faulty ELT, a pass
indicates a faulty G-Switch
The testing of the remote controller switch is a simple continuity test and the ELT
itself cannot be tested other than the built in test. The G-Switch is electrically tested
by inducing an overload condition into the solid state ‘G’ switches. If such a failure
occurs then the G-Switch should be replaced.
If using the 503-51, a BIT failure is indicated by the FAULT lamp illuminating.
4.4 Diagnose mode
This mode is used when a G-Switch/ELT system has failed its self-test and been
removed from the aircraft, and is useful to an operator to indicate what part of the
system has failed.
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Note:- An antenna or equivalent load must be connected to the ELT when
performing tests.
The G-Switch needs to be connected to a 28V power supply and a remote controller.
System diagnosis is performed by ensuring that the locking toggle switch on the
G-Switch is in the centre OFF position, and switching it to armed whilst the
test switch is held in the test position. When a single bleep is heard, the test switch
is released. The G-Switch will then test the system, but rather than just giving six
bleeps to indicate a failure, will produce differing numbers of bleeps according to the
fault(s) as follows: -
Bleeps Fault
2 Communications failure between the G-Switch and ELT.
3 G Force sensor 0 failure.
4 G Force sensor 1 failure.
5 G Force sensor 3 failure.
7 ELT battery failure.
8 ELT RF failure
9 ELT test failure
10 Sounder failure
A single bleep indicates that the diagnostics are completed. In the event of more
than one fault there is a one-second gap between each set of bleeps. The G-Switch
will not be able to read the ELT test results if there is a communications failure.
4.5 Repair
No maintenance over and above physical inspection and battery replacement is
possible at other than at the manufacturers.
4.6 Antenna
The antenna and R.F feeder should be subject to VSWR test using a Techtest
Test Set 12-602-8 on an annual basis.
4.7 Operation
When any part of the ELT system is disturbed the built in test should be initiated
(see Operating manual) and the results recorded. Actual transmitted data can be
monitored on a Test Set 12-503-26
Note : The Test Set has its own separate manual.
5. RECHARGING & CONDITIONING THE G-SWITCH BATTERY PACK
Overview
The G-Switch is tted with a removable re-chargeable battery pack consisting of ve
Nickel Metal Hydride cells series connected, with a protection device. The function of the
battery pack is to provide power to the G-Switch in the event of the aircraft losing electrical
power. The capacity of the battery pack is high in comparison with the current drawn by
the G-Switch .

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The G-Switch charging circuit works as follows. When the battery is fully discharged
there is a set time in trickle charge, (as fast charging a completely discharged battery can
damage it) followed by a fast charge. When fully charged, trickle charging re-commences.
5.1 TESTING THE BATTERY PACK
Testing a battery under load is the best way to gauge its condition. The following
table of measurements are intended to help ascertain the condition of the battery
pack, but is only intended as guide.
BATTERY CONDITION TERMINAL STATUS POTENTIAL
Just completed charging cycle Open circuit 6.5V to 7.2V
Just completed charging cycle 100 Ohm resistor
connected across terminals
6.9V
dropping rapidly
15 minutes after test on load 100 Ohm resistor
connected across terminals
6.5V
dropping slowly
After testing the battery can be put back on trickle charge to replace any lost charge.
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6. ILLUSTRATED PARTS
Figure 1
ELT 503-1 (with battery tted)
Recessed ON/OFF
Test/Reset switch
Battery removal clip
RF Output
TNC connector
503-1 ELT
A0673-1
ELT battery pack
G-Switch interface
connector
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Figure 2
G-SWITCH
503-7 & 503-19
26 way ‘D’ type
Connection to
503-1 Transmitter
Figure 3
G-SWITCH with GPS
503-35 & 503-36
26 way ‘D’ type Connection to
503-1 Transmitter
GPS
ARM/OFF/ON
Toggle Switch
TEST/RESET
Switch
ARM/OFF/ON
Toggle Switch
TEST/RESET
Switch
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Figure 5
REMOTE CONTROLLER
503-52
9 way ‘D’ type connector
tted with screwlocks
DZUS Fasteners
ON/Test/Reset
Switch
System Function
Indicator Lamp
Figure 4
REMOTE CONTROLLER
503-4, 503-17, 503-20 & 503-53
DZUS Fasteners
9 way ‘D’ type connector
tted with screwlocks
ON/Test/Reset
Switch
System Function
Indicator Lamp

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Figure 7
FIXED MOUNTING TRAY
A0637-1, A0637-3, A0637-5
Figure 6
AF/AP ELT COCKPIT CONTROLLER
503-51
19 way circular connector
DZUS Fasteners
Transmit Switch
with guard
Inhibit Switch
with guard
Test/Reset button
Fault Indicator
Transmit/Test
Indicator
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10-274-1 Portable
Antenna
Quick Release
Buckle and Strap
Figure 9
QUICK RELEASE TRAY
A0637-8
Figure 8
FIXED / PORTABLE MOUNTING TRAY
A0637, A0637-6
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Figure 10
INTERFACE UNIT
503-15 Series
Figure 11
WATER ACTIVATED SWITCH
503-23-1
3 way circular connector Air Outlet hole
Water Inlet holes
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Figure 12
10-102-19 ANTENNA
Figure 13
10-102-29 ANTENNA
Figure 14
10-118-28 ANTENNA
Figure 15
10-118-35 ANTENNA

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Figure 18
10-264-35 ANTENNA
Figure 19
10-274-1 ANTENNA
Figure 16
10-118-32 ANTENNA
Figure 17
10- 152-19 ANTENNA
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