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NC Bill


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My plane is in annual. ELT batteries were found to be dead. Replaced yesterday.


Yesterday morning I get a call for AFRescue saying my ELT has gone off so please check it out. A&P is at home and he left plane in his hangar! He returns and turns it off and rechecks wiring. Same sequence occurs again last night. Unit will be taken to avionics shop today.


Any thoughts or suggestions appreciated.

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Make sure your mechanic complies with the new AD on the AmeriKing ELT. To me it sounds like you have a new ELT in your future. that seems to be one of the failure modes for the ELT.

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I don't believe that the 451 does this, but many 406 ELTs will initiate transmitting anytime the batteries are replaced. This can lead to an unexpected ELT transmission and subsequent running down of the batteries.

FAR 91.207 specifies the required inspections for an ELT. Owners should confirm that these inspections are accomplished every 12 calendar months (does not have to coincide with a condition inspection). These inspections should be captured by the required condition inspection procedures for the aircraft in the SLSA world, but I would not assume that they are. In the case of FD, the Condition inspection checklist omits the check of the crash sensor.

As for the AD, FD should have issued a Safety Directive to transmit this AD and its mx requirements, but I bet that they have not done that.

A 406 ELT (Ameriking 451 is a 406 unit) transmits actual intelligence, not just an audible sweeping tone as the 121/243mhz units did. It is arguable as to whether this intelligence needs to be verified at each 91.207 inspection or not. I make the case that 91.207 requires a verification of "sufficient radiated signal" from the transmitter antenna. In my opinion, a check of the 406 data output is required for compliance with 91.207 on 406 MHz ELTs. I have found several ELTs that were programmed wrong (wrong N number or Hex ID), that had been in service for a while.  

Doug Hereford

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