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Old 02-13-2012, 01:54 AM   #1
jgnunn
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I am having a dilemma as to where to locate the ELT antenna. I don't want it on top. The belly is already having the COM and transponder antenna down there (I believe they have to be approx 36" apart so running out of room down there). My turtledeck is fortunately wood, so I am looking at locating the antenna as in the pic below. It is a compromise i know, since it will follow a curved path and not vertical. Having researched this subject, I am amazed at some of the very odd (and obviously far from ideal, and sometimes useless) locations these things are put....It seems that because they don't really work too well ( and often not at all), I get the impression that many builders just stuff them anywhere out of the way so they can check it off and say they have one on board.
Anyways.. thoughts on my location?



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Old 02-13-2012, 04:20 AM   #2
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I think that where you have it is fine. My opinion is that it serves only a reglatory function and not a safety function. Face it, how many elts alerts are real, what happens when 85%+ are false - no one takes it serriously. Assuming they do take it for real, how many hours before they find you, and will that make a difference? I trust my cell phone/ wife's expectation on when I should be home, and anyone watching the crash or the resulting smoke. I am not counting on an elt to save me from anything. Another case of the goverment mandating what they think I need and a typical knee jurk reaction.

sorry for the soap box,
larry



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Old 02-13-2012, 05:47 AM   #3
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I think that is good Beej.

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Old 02-13-2012, 03:32 PM   #4
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Most ELT alerts are not real. However, every one of them is taken very seriously. The trouble with the ELT (121.5) today is that satellites no longer monitor this signal. So, location time will take much more time. The 406 mhz system is the only one monitored by sat. With much more precision leading to much faster location. All air carriers monitor 121.5. Today's 121.5 elt sensing is relied on the monitoring of us fliers. Cell phones are fine if you're able to make the call. PLB's (406 mhz) are gaining popularity. One day, just not this day, the 121.5 versions will not be available. So, unfortunately for now we must have them. They do work.

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Old 02-13-2012, 04:07 PM   #5
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I was told the way the industry is going to regulate old 121.5 units is to stop selling the batteries. Only the D cell types will be legal at that point because of battery freshness. Win Win for FAA and manufacturers. No new legislation, and obsolete means buying a new unit.

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Old 02-13-2012, 06:06 PM   #6
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Quote:
Originally Posted by larryM
I think that where you have it is fine. My opinion is that it serves only a reglatory function and not a safety function. Face it, how many elts alerts are real, what happens when 85%+ are false - no one takes it serriously. Assuming they do take it for real, how many hours before they find you, and will that make a difference? I trust my cell phone/ wife's expectation on when I should be home, and anyone watching the crash or the resulting smoke. I am not counting on an elt to save me from anything. Another case of the goverment mandating what they think I need and a typical knee jurk reaction.



sorry for the soap box,

larry
Anyone know why the Steve Fossett accident was not found? I am assuming that the Citabria had a functioning ELT and search teams were out there.ELT working?, search system in effect. Strange!
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Old 02-13-2012, 06:57 PM   #7
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I think the pilot was relying on a watch which contained a "distress transmitter." Maybe the antenna was never deployed. The debris was small and scattered. The 406 mhz systems are the way to go. Response time is quick. I don't know anything about building a Skybolt, but, I do know about ELT's and SAR. Going to Palm Bay in May, perhaps OSH in Jul and then starting my build late this summer. I'll attend one or two eaa workshops during the year as well. This is the last of my deviation from this "electrical" section. Thanks for your efforts jgnunn.

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Old 02-13-2012, 07:35 PM   #8
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No problem with that location at all Beej.I have installed in that location or similar in 6 or 8 different aircraft and the wooden structure is fine and a small curve wont trouble it at all, in fact I have seen someone bend one to about a 30 degree angle and the signal strength was still fine (406mhz however).To tell you the truth it is a great location as the antenna is unlikely to be damaged in an accident.406mhz units are mandatory here in NZ (a lot of our terrain around here is seriously hardcore)and we have had several accidents without ELT activation (particularly helicopter) by G switch. Dont rely on the G switch, fit the instrument panel remote and use it, it far easier to turn it off and explain to SAR after the fact than not and have a G switch failure or have the antenna wiped off the airframe.The biggest problem with the 406 ELT's is the antenna, the tuning is fairly critical (ground plane critical also) and as they are externally fitted on most aircraft you have to think about its chance of being wiped off (or even bent a little)in a crash when installing.The 406 ELT's still broadcast on 121.5 (as well as 406mhz) as they use this for the homing signal when the helo is coming to pick you up.Things to remember;It takes 50 seconds (approx)for the 406 to activate (by panel switch) so if you have an engine failure or impending crashturn it on ASAP and dont rely on the 'G' switch.If spending the money get a unit like the Kannad 406mhz with integralsatellite antenna, if the main antenna is damaged it will still send a signal via satellite.Remember also that 99% of these 406 ELT's do not ship with an antenna that allows you to take it away from the aircraft (except for the above mentioned GPS type as it is internal) it has to be purchased as an optional extra, so although your lovely new 406 ELT is easily removed from its mounting bracket with a lovely clasp or velcro strap it wont do squat.Dont fit the antenna in a location that will have it easily damaged in an accident, think about this from every aspect such as a tip over also.
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Old 02-14-2012, 01:20 AM   #9
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John,
Not the new model but adel clamped it below the turttledeck. i have a Pacer next door and duplicated the installation except had to bend the antenna.
Dennis in Chicago




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Old 02-14-2012, 01:24 AM   #10
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Thanks all, sounds like I have a reasonable, if not the best location for the antenna that I can hope for. Dennis, my unit is behind the rear seat.

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Old 02-15-2012, 06:16 AM   #11
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ELT will probably not work after a crash - I got this stat from the SARtechs we work with. They say that better would be a Spot Messenger doing double duty for satellite tracking and an emerg call. Legalities still ask for an ELT installed on an airplane though.

ELT's still work on the ancient "signal fire" concept, where they have to function long enough for the expiry of your flight plan plus the search time of your route. 406 with a gps location are better, but still transmit a 121.5 "homing" signal after the 406 gets your location in the ballpark. Which is why the whole battery size figures so prominently in the technology of the ELT. Lot's of "ifs": no post crash fire, antennas intact, clear view of the sky, g-switch worked properly, etc, etc bringing the prob below 50%.

With a Spot, it is tracking automatically all the time, you punch the 911 button and instant call for the cavalry. Instead of high altitude SARSAT satellite, it uses the low altitude Globalstar ones, so not a lot of battery required to transmit a signal. Will transmit location every 5 minutes untill the 2 AAA batteries die a week later (longer than an ELT), but all you really need is that first shot with your lat/long unless you are adrift on the ocean.

You pays your money and takes your chances.Edited by: Guido Lepore

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Old 02-15-2012, 05:29 PM   #12
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I have a SPOT for my boat, mounted with velcro on the life raft canister when off-shore. $100 up front for the unit (on sale) and $100 a year for the basic tracking service.

It has an "I'm OK" button that I push every 2 hours when traveling. That sends an email with the message of my choice (Having a wonderful time, wish you were here.) to my friends and family. This also gives them a link to a map of my present position and will show the previous spots like bread crumbs. This mode can also be set to trigger based on time.
Here is one of my friends Spot logs.
http://share.findmespot.com/shared/f...3MlgpIQIYeVGXP
My current position.
google.com/maps?f=q&hl=en&geocode=&q=21.22932,-86.73392&ll=21.22932,-86.73392&ie=UTF8&z=12&om=1

It has a "I need help" button that will send message to your email list if you want help but think one of your friends would be able to solve the problem.

Then is has an "OH S..T, HELP!, SEND OUT THE TROUPS, 911" button that makes an immediate, official SOS call to the athorities. When I get another airplane I'll put a velcro patch on the top of glare shield for it.

The UWYO carries one in the re-search King Air that is currently set to leave a trail every 2 min. so staff interested in the project get constant updates. A current project is to see if it is practicable to seed clouds from a mountain. This is very useful when we have people on the ground cross referencing their actions and wx conditions with data the airplane is gathering above them. Not something we would be doing with a biplane though. [img]smileys/smiley9.gif[/img]

I should have mentioned that it is very small. Like less than 1/3 the volume of a pack of cigaretes.





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Old 02-15-2012, 06:21 PM   #13
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Does your ship have two blue tarps on it?

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Old 02-15-2012, 07:50 PM   #14
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"Does your ship have two blue tarps on it?"

Yep. Though "ship" is a bit more than it deserves. [img]smileys/smiley9.gif[/img]


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Old 02-15-2012, 08:33 PM   #15
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RE: Steve Fossett accident
He probably didn't turn it on standby. Had it set to off.
Edited by: Biplane45
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Old 02-15-2012, 11:28 PM   #16
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Quote:
Originally Posted by Biplane45
RE: Steve Fossett accident
He probably didn't turn it on standby. Had it set to off.
Why would you opine that?
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Old 02-16-2012, 03:12 AM   #17
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I read the report and there is no mention of what you opined. The only mention of the elt was this:
"The airplane's ELT was destroyed; numerous pieces of itsorange plastic case and internal circuit board components were found scattered in the debris field."
Did I miss something?Edited by: TxSkyBolt
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Old 04-17-2012, 08:07 PM   #18
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I have been involved in some conformity issues with an aircraft here at our shop and wanted to revive this thread briefly.

I am sure that you builders have read the regulations and already know this, but 14CFR 91.207 states that after June 21, 1995, an emergency locator transmitter that meets the requirements of TSO-C91 may not be used for new installations. In other words, if you plane was built after 21 June 1995 and it is equipped with a 121.5mhz ELT, then you are in violation of the regulation.

This came up with an airplane we are rebuilding here. It was built in 1972, however it was completely stripped down of all equipment at some point prior to us taking on this project. The FAA rep has argued that this is a new installation. We have argued that it is not. The plane was certified with a 121.5 ELT, and therefore we believe that placing one back into the plane is a replacement to a previous installation. The FAA rep believes that once the old equipment is out, anything back in is a new installation. Semantics.

We thought about pressing this issue through appeals to the Washington office, however in the end we decided that it was cheaper and more prudent to just install a 406mhz ELT.

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Old 04-17-2012, 10:03 PM   #19
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Why not inquire of the FAA General council and the answer will be official. Very easy to do (I've done it twice) from the FAA website.

Best regards,

Brad

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Old 04-17-2012, 11:33 PM   #20
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we had a similar discussion on our conversions of adding turbines to cessna 210s. in the end its a "new" airplane, but with a 78-83 airframe. what we came up with is, if we dont need to replace the ELT due to it not working properly, inop g switch or off freq, we can use the old (121.5mhz) one. if we need to replace it, it needs to be replaced with a 406mhz.

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Old 04-18-2012, 03:26 AM   #21
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Is this relevant to Certified only?

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Old 04-20-2012, 02:15 AM   #22
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Quote:
Originally Posted by cashflyer View Post
I have been involved in some conformity issues with an aircraft here at our shop and wanted to revive this thread briefly.

I am sure that you builders have read the regulations and already know this, but 14CFR 91.207 states that after June 21, 1995, an emergency locator transmitter that meets the requirements of TSO-C91 may not be used for new installations. In other words, if you plane was built after 21 June 1995 and it is equipped with a 121.5mhz ELT, then you are in violation of the regulation.

This came up with an airplane we are rebuilding here. It was built in 1972, however it was completely stripped down of all equipment at some point prior to us taking on this project. The FAA rep has argued that this is a new installation. We have argued that it is not. The plane was certified with a 121.5 ELT, and therefore we believe that placing one back into the plane is a replacement to a previous installation. The FAA rep believes that once the old equipment is out, anything back in is a new installation. Semantics.

We thought about pressing this issue through appeals to the Washington office, however in the end we decided that it was cheaper and more prudent to just install a 406mhz ELT.
You can still purchase 121.5mhz ELTs that are TSO-C91a. You just can't put the older TSO-C91 121.5s into new aircraft.

Best regards,

Brad
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Old 04-20-2012, 10:58 PM   #23
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Quote:
Originally Posted by larryM View Post
My opinion is that it serves only a reglatory function and not a safety function. Face it, how many elts alerts are real, what happens when 85%+ are false - no one takes it serriously.
I have to admit it's the first time I've heard that argument.

Where I come from there are many areas where your cell phone won't help you. But if you end up putting your plane down in a survivable way, your 406 ELT certainly will get help coming if no-one heard your distress call or you didn't manage to squeeze one out.

As for not taking it seriously, this is untrue. We've had numerous people saved in this country after an ELT activation, from yachties to bushwalkers. It's a bit like saying that fire crews don't take building fire alarms seriously because 8 out of 10 are false alarms. In fact they turn up lights & sirens wailing every single time, because occasionally the building is actually on fire.


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