Hi netters. The requirement to have a remote panel switch (as well as a way of determining that the ELT is on... either via a light or by audible tone..... plus a way to silence it from the panel) was by way of a change to F.A.R. 91. This change occurred back in 1995 and was a simple change requiring all new installations to conform to a new TSO C91a. The old TSO (C91) only required that the ELT have a "G" sensing switch. With the increase of false activations etc, the new generation of ELT's needed a way to detect a false activation and to silence the unit. Hence the change in the T.S.O. number. In this respect, it should be pointed out that the older (T.S.O. C91) ELT's should not be considered for new installations. I know of some A/C that have passed inspection with an older unit installed, but only because the DAR was not familiar enough with the regulations to catch it.
Besides, most of the newer ones (ACK is my choice) use standard "D" cell batteries and are much more economical to service. John Sickafoose EAA Tech counselor Naples, Fl
