Home' RTCA Documents for Review : DO-204B, MOPS Aircraft ELT 406MHZ Contents © EUROCAE, 2018
Distances D-1, D-2 and D-3 are discretionary.
FIGURE 3-4: ELT RF Intermodulation Test Set-Up
At the maximum and minimum operating temperatures, the EIRP level at each carrier
frequency shall not be less than 17 dBm (50 mW), within 5 minutes following manual
or automatic activation.
3.9 OPTIONAL 406 MHZ HOMING TRANSMITTER
Cospas-Sarsat compliant ELTs may optionally include a 406 MHz homing transmitter,
if present it shall comply with the requirements in C/S T.001 or T.018 as applicable. At
the end of the declared useful life of its internal or integral battery, the ELT system
shall be capable of continuous operation of the 406 MHz homing transmitter for at
least 48 hours at any temperature within the range -55°C to +70°C (Class 0), -40°C to
+55°C (Class 1) or -20°C to +55°C (Class 2) in the transmitting mode that requires the
highest power consumption.
The ELT unit shall be marked with its type, capability ID code as defined in § 1.3, and
for ELT(S) with its category. The mark shall identify the applicable capabilities in a
concatenated string in the order as the codes are presented in the TABLE 1-1. For
example, a first generation ELT(AF) class 1 with GNSS, 121.5 homing will have on the
mark ELT(AF) T.001/G/H1/C.
If the ELT system contains a crash sensor, the component of the ELT system
containing the crash sensor shall be clearly marked by the ELT manufacturer to
indicate the correct installation orientation(s), if appropriate, for crash sensing.
Additional marking specifications are defined in § 3.3.3 for batteries, §
220.127.116.11 for ELT(S), § 3.8.2 for voice modulation.
Instructions for disabling the unit for storage or disposal shall be clearly and simply
presented on the outside of the case. For all (AP) and (S) type units, clear instructions
for use shall also be provided.
3.11 CASE DESIGN ATTACHMENT AND COLOUR
The exterior of the ELT system components shall have no sharp edges or projections
which could damage inflatable survival equipment or injure persons.
ELT controls shall be protected to minimise the risk of inadvertent activation of the
ELT and the possibility that flying debris during a crash, or passengers and crew
evacuation following a crash, will deactivate the ELT.
All ELT units shall be predominantly of a high visibility yellow or orange colour, except
for those portions of ELT(AD) units that are on the exterior surface of the aircraft.
Except for ELT(S), the equipment shall have a means of attachment so that the ELT
will withstand the tests contained in § 4.5.8 and § 18.104.22.168 in all directions without
breaking loose from the mounts, damaging the equipment, or otherwise causing the
ELT not to activate. The means to attach the automatic ELT to the aircraft can include
a separate bracket or mount. The bracket or mount is part of the ELT system and shall
be attached to the ELT unit for all testing which is applicable. The mechanism for
attaching the ELT to the bracket or mount shall not be of a hook and loop fasteners
3.12 INSTALLATION MANUAL
The ELT manufacturer shall provide an installation manual which includes at a
minimum, the ELT's type, class and capabilities designations, a description of the
ELT's operational capabilities, installation instructions and any additional information
regarding the installation and operation of the ELT which is necessary to ensure
compliance with this MOPS.
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