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  #1  
Old 08-20-2017, 05:29 PM
guccidude1 guccidude1 is offline
 
Join Date: Mar 2008
Location: Reno NV
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Default Condition Inspections and the 406 ELTs

Guys: How is everyone who has a 406 ELT checking them IAW the annual/condition inspections requirements? I know about the AM radio trick for the 121.5 ELTs. Is there another way to check, or has anyone designed a 406 mz receiver circuit. Hoping for the latter. Dan from Reno
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  #2  
Old 08-20-2017, 05:39 PM
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snopercod snopercod is offline
 
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Originally Posted by guccidude1 View Post
Guys: How is everyone who has a 406 ELT checking them IAW the annual/condition inspections requirements?
Supposedly they have an internal mechanism to test the 406 MHz. Every three months you're supposed to press the "test" button and you get a series of beeps back, telling you if there's a problem. You can hear the 121.5 sweeps on your radio, but AFAIK there's no way to actually hear the 406. I could be wrong. Also, every year as part of your annual you're supposed to test the G-switch by giving the unit the shake test to make sure it sets off the unit.
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Old 08-20-2017, 08:34 PM
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Are you sure you are suppose to set off an actual G activated alarm crash signal?
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  #4  
Old 08-20-2017, 10:06 PM
Tracer 10 Tracer 10 is offline
 
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Default Testing 406 ELT

If you don't have the manual; go online to the manufactures website & download the instructions. It will explain how to test it.
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Old 08-21-2017, 06:24 AM
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snopercod snopercod is offline
 
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Are you sure you are suppose to set off an actual G activated alarm crash signal?
Yes, according to AKC E-04 manual, the G-switch must be tested at least every 12 months to maintain airworthiness. You do it during the first 5 minutes after the hour, and reset the ELT after you hear three sweeps on 121.5. The 406 MHz signal isn't activated until 50 seconds (?) later so it is never broadcast.

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Leave the ELT in the “Armed” position, then remove the ELT from the aircraft, and perform a G switch test as follows:

This test should be conducted between the hour, and 5 minutes after the hour per FCC requirements. Tune an aircraft radio, or hand held aircraft radio to 121.5 MHz. The radio should be in close proximity to the area where you will conduct the test.

TURN THE SQUELCH CONTROL ALL THE WAY DOWN, OR OFF. You should be hearing white noise on the radio. If switching the main switch from the “Off” to the “Armed” position wait at least 15 seconds before performing this test. While in the “Armed” position, hold the ELT at your waist with the arrow printed on the battery case facing away from you. Move the ELT rapidly away from your waist. When the ELT reaches the full extent of your arm, retract it back to your waist as fast as possible. You should hear the 121.5 MHz sweep tone in the radio. AS SOON AS YOU HEAR THE TONE, IMMEDIATELY TURN THE MAIN SWITCH ON THE ELT TO THE “OFF” POSITION.
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Old 08-22-2017, 09:47 AM
Canadian_JOY Canadian_JOY is offline
 
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Quote:
Originally Posted by snopercod View Post
Yes, according to AKC E-04 manual, the G-switch must be tested at least every 12 months to maintain airworthiness. You do it during the first 5 minutes after the hour, and reset the ELT after you hear three sweeps on 121.5. The 406 MHz signal isn't activated until 50 seconds (?) later so it is never broadcast.
Ummm, that last bit isn't quite true. In order for the built -in-test (BIT) to fully test the ELT, the ELT must transmit on 406. The 406 burst that is sent is sent with one of its digital bits "flipped" to indicate it is a test message and should be ignored by the SAR system. As you've stated, at the 50 second point a valid distress signal will be sent.

Also, of critical importance... The 406 signal is very high power as compared to the 121.5 signal - typically it's a 50X higher power transmission. As a result, triggering a 406 transmission without an antenna connected could cause catastrophic damage to the ELT. Always always ensure the first connection made to the ELT is the coax. Once the coax is in place (with an antenna on the other end of it! LoL) then connect any other cabling to the ELT. Same goes in reverse... the last connection to be disconnected is the coax. Following this little rule of thumb may save you from frying your ELT.
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Old 08-22-2017, 10:58 AM
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snopercod snopercod is offline
 
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Thanks for the correction. I didn't know that.
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Old 08-22-2017, 12:14 PM
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az_gila az_gila is offline
 
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Smile 3 month self-test

Quote:
Originally Posted by snopercod View Post
Thanks for the correction. I didn't know that.
Well, it's not quite a correction...

If you perform the required 3 month checks by using the cockpit remote panel the unit will self check the 406 portion as required by the manufacturer. Note that this is similar, but a separate check from the G-switch test mentioned above.

YOU MUST PERFORM A SELF TEST EVERY THREE MONTHS to verify the ELT is functioning properly.

To perform the self test, make sure THE AIRCRAFT MASTER SWITCH IS OFF AND THERE IS NO POWER APPLIED TO THE ELT THROUGH THE GPS INTERFACE. Tune an aircraft radio to 121.5 MHz, and turn the squelch all the way off to listen for the modulated carrier.
With the ELT main switch in the “Armed” position, and not operating, press the “Reset/Test” button on the cockpit remote control (RCPI) once. You will hear one second of 121.5 audio on the radio, followed by either one beep from the audio alert indicator, or one beep followed by a two second delay, and a second beep if all systems are functioning properly. The light will also flash on the remote. (The flashes are random and have no meaning)
System OK codes: One Beep or One Beep followed by a second beep two seconds later.
A series of 2 – 5 fast beeps, a 2 second delay, and the beep series repeating again indicates there is a self test function that has returned a trouble condition. The ELT will not be disabled, but it should be inspected by a qualified avionics facility as soon as possible.
The trouble code returns a series of beeps with a two second delay, and then the trouble code is repeated one more time. The first beeps alert you that there is a trouble condition. The two second delay is to allow you to be ready to count the second set of beeps.
Trouble code sequence: 2-5 beeps — two second delay — 2-5 beeps
TROUBLE CODES:
2 BEEPS→ BATTERY LOW
3 BEEPS→ LOW RF POWER
4 BEEPS→ FREQUENCY NOT LOCKED
5 BEEPS→ HIGH VSWR OR HIGH CURRENT
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  #9  
Old 08-22-2017, 12:34 PM
Canadian_JOY Canadian_JOY is offline
 
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Please note the information provided above is specific to one make and model of 406 ELT. Make sure you use the documentation for your specific ELT to conduct testing.

Vis a vis G-switch testing, yes, a valid 406 signal will be sent after 50 seconds. Depending on the particular ELT, you may hear the 121.5 signal immediately upon activation of the G-switch (again, consult the manual for your particular ELT). If you hear the 121.5 that is confirmation the ELT has activated. Reset the device and check that test off your list. You should still do the manufacturer-recommended self-test as suggested by Gil - best if that test is also done as part of your annual condition inspection, thus you get a comprehensive self test and confirmation of the G-switch operation.
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  #10  
Old 08-22-2017, 12:58 PM
12vaitor 12vaitor is offline
 
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Location: Panama City, FL
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I think one critical paragraph was left out of the G switch test:

ACK ELT-04, Section 10, para g. "The ELT when activated transmits on 121.5 MHz for approximately 50 seconds before a 406 MHz burst is sent to the satellites. This is a live burst which will immediately notify the COSPAS/SARSAT system that there is an emergency. IT IS IMPERATIVE THAT YOU DO NOT ALLOW AN ACTIVATED ELT, TO TRANSMIT FOR MORE THAN 30 SECONDS DURING ‘G’ SWITCH TESTING."

Section 9 also indicates the quarterly self-test ('reset/test' activation) will generate a test burst on 406 Mhz for 550ms.

You can also find some good information on beacon testing here: https://cospas-sarsat.int/en/testing...406-mhz-beacon

Basically, live testing on 406 Mhz is not allowed.

John Salak
RV-12 N896HS
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