ACR&Artex G406-4 ELT - Manual (Page 56)

ACR ELECTRONICS, INC / ARTEX PRODUCTS
DESCRIPTION, OPERATION, INSTALLATION AND MAINTENANCE MANUAL
G406-4 (453-5012)
25-62-21
Page 56 of 86
JUL 31/12
SUBTASK 25-62-21-990-005
E. RTCA
(1) DO-204, § 3.1.8 guidelines for mounting a ELT:
(a) The ELT shall be mounted to primary aircraft load carrying structures, such as trusses,
bulkheads, longerons, spars, or floor beams.
(b) The mounts shall have a maximum static local deflection no greater than 0.1 inches (2.5
mm) when a force of 100 lbs (450 newtons) is applied to the mount in the most flexible
direction. Deflection measurements shall be made with reference to another part of the
aircraft not less than 1 foot (0.3 meters) nor more than 3 feet (1.0 meters) from the
mounting location.
(2) DO-182, § 6.2.2.b recommends that:
(a) To maximize the probability of the ELT transmitting a detectable signal after a crash, all
ELT system components, which must survive a crash intact, e.g., transmitter and
external antenna, should be attached to the airframe in such a manner that the
attachment system can support a 100 g load, (ELT weight x 100, ELT antenna weight x
100, etc.) applied through the center of gravity of the component (ELT, antenna, etc.) in
the plus and minus directions of the three principal axes of the aircraft.
(b) Post-crash critical components of the ELT system, e.g., transmitter and external
antenna, should be mounted as close to each other as possible.
(c) The antenna coax cable should not cross any production breaks, e.g., major structure
sections, such that the ELT and antenna are in the same section of the aircraft and as
close together as possible.
(d) If the ELT and external antenna are on opposite sides of an airframe production break,
the components should be secured to each other by a tether that can support a 100 g
load (ELT weight x 100). The interconnecting antenna-to-ELT coax cable should have
sufficient slack on both ends that it will not be subjected to any tensile load and should
be tied loosely to the tether.