406ELT FAQ's and FACTS
I received a call today from an authorized repair center
describing another situation where a 406ELT was shipped to
them (at the owners expense) only to find out that there was no
problem with the ELT. Since 406ELT's are more capable they
are are also more complex. It comes with all technology we
adopt in our lives and we can educate ourselves to ensure we don't
spend our money unwisely.
Let me immediately begin by offering one simple troubleshooting technique that could help prevent this unnecessary cost. Disconnect the ELT from its other devices(except the antenna). Once isloated, toggle the ELT mounted switch to "off" or "reset" and then back to "arm". The ELT will run another self test and provide feedback via the indicator light. If the ELT passes the self test, the problem exists somewhere else in the installation. The antenna is left connected so that the 5 watts of power generated by the transmitter doesn't damage the internal circuitry.
The number of internal checks performed vary by manufacturer but they have many in common. Experience has shown that once the ELT has been installed and tested, most of the parameters will remain unchanged and will not likely result in a fail signal. Some failures that are likely to result in a problem indication are: Battery power low, RF output low or programming data not present.
Battery power low is an ELT problem and may not be expected if the ELT has been in service for less than 5 years. The most probable causes for this are over testing or ELT left in the "on" position too long. Since the FAA requires that any ELT battery be changed once the accumulated transmission time exceeds one hour it is clear that setting the system to "on" should be limited to actual need. Unfortunately at least one manufacturer uses the "on" position to perform self tests instead of a dedicated "test" position and this quickly accumulates towards transmission time.
On installations interfaced with GPS it is possible for the programming data test to be a cause for failure. With the interface, aircraft data and GPS data are combined into a single message and if one piece is missing a test fail will result. This is usually caused from GPS power turned off, GPS menu settings inproperly set or a wiring problem of some sort.
External components can play a role in failed tests and it is helpful to understand the possible causes. A failed test caused by other components other than the GPS is low RF Output. There are several poosible errors that can cause this. These include mistakes in the wiring between the remote switch and the ELT, improper grounding of the ELT, a bad coaxial cable connection or poor antenna grounding.
Unfortunately problems caused by poor workmanship or faulty grounding do happen and can only be detected and corrected by a competent avionics shop but by using the component isolation method an aircraft owner can be empowered enough to avoid unnecessary shipping costs to repair centers.
Happy Flying.
Let me immediately begin by offering one simple troubleshooting technique that could help prevent this unnecessary cost. Disconnect the ELT from its other devices(except the antenna). Once isloated, toggle the ELT mounted switch to "off" or "reset" and then back to "arm". The ELT will run another self test and provide feedback via the indicator light. If the ELT passes the self test, the problem exists somewhere else in the installation. The antenna is left connected so that the 5 watts of power generated by the transmitter doesn't damage the internal circuitry.
The number of internal checks performed vary by manufacturer but they have many in common. Experience has shown that once the ELT has been installed and tested, most of the parameters will remain unchanged and will not likely result in a fail signal. Some failures that are likely to result in a problem indication are: Battery power low, RF output low or programming data not present.
Battery power low is an ELT problem and may not be expected if the ELT has been in service for less than 5 years. The most probable causes for this are over testing or ELT left in the "on" position too long. Since the FAA requires that any ELT battery be changed once the accumulated transmission time exceeds one hour it is clear that setting the system to "on" should be limited to actual need. Unfortunately at least one manufacturer uses the "on" position to perform self tests instead of a dedicated "test" position and this quickly accumulates towards transmission time.
On installations interfaced with GPS it is possible for the programming data test to be a cause for failure. With the interface, aircraft data and GPS data are combined into a single message and if one piece is missing a test fail will result. This is usually caused from GPS power turned off, GPS menu settings inproperly set or a wiring problem of some sort.
External components can play a role in failed tests and it is helpful to understand the possible causes. A failed test caused by other components other than the GPS is low RF Output. There are several poosible errors that can cause this. These include mistakes in the wiring between the remote switch and the ELT, improper grounding of the ELT, a bad coaxial cable connection or poor antenna grounding.
Unfortunately problems caused by poor workmanship or faulty grounding do happen and can only be detected and corrected by a competent avionics shop but by using the component isolation method an aircraft owner can be empowered enough to avoid unnecessary shipping costs to repair centers.
Happy Flying.
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