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Old 01-19-2012, 10:33 AM
flyenforfun's Avatar
flyenforfun flyenforfun is offline
Join Date: Aug 2009
Location: Wilmington DE
Posts: 325

Originally Posted by dbuds2 View Post
Got my ACK-406 from Van's and after lots of reading and searching like you're doing, I'm mounting both the ELT and the anntennae on the outboard rib of my right wing. The stiffness from the skin and spar satisfied me for the mount of the ELT and the anntennae should always have visiablity to the sky thru the fiberglass wing tip.
The antenna will function fine without pointing vertical?
Matt Giordano Sr. and Jr.
RV-8 - N861MM
Wilmington, DE

Last edited by flyenforfun : 01-27-2012 at 01:06 PM.
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Old 01-20-2012, 11:38 PM
Berchmans Berchmans is offline
Join Date: Nov 2009
Location: Anchorage, Alaska
Posts: 467
Default ELT Mount

Here is my mount

Following is my construction sequence.

I used 2 pieces of 1/2 X 1/2 angle cut to match the length of the rear cargo area upper shelf. I match drilled three 8-32 screw holes in the angles using the holes in the edge of the cargo deck as a drill guide. I then cut some 1/8" by 2" wide stock to span between the two angle pieces when placed on the upper and lower longeron. The next step was to drill through the lower angle and attach the two pieces of 2" wide aluminum at proper spacing to attach the ELT mounting plate. I installed K1000-8 nutplates on the angle to allow me to install the 8-32 X 1/2 inch cap screws that I used to fasten the angles and 2" stock together. I then fastened the lower mount angle and the two pieces of 2" stock to the lower longeron using the same 8-32 screws used to install the cargo floor. I then laid the upper angle on the top longeron and clamped it to the 2 inch wide stock. With the upper angle clamped to the stock I removed the entire assembly from the plane. On the bench I then drilled the 2 inch stock and the upper angle, installed nut plates on the upper angle and re-assembled the mount completely. Next step is to re-install the assembly in the plane again using the 8-32 screws to hold the lower angle in place on the longeron and cargo floor. With this in place you can use the upper angle which is fairly rigid as a drill guide for drilling through the upper longeron with a 90 degree angle drill. Fasten the top angle in place with 8-32 hardware.

The only real down side I see to this is that in order to access the rear mounted battery it will also be necessary to remove the ELT and mount. Other than that it's a pretty clean installation.

You must be careful in drilling the upper Longeron the keep the holes centered in order not to compromise the Longeron.
Burke Wick
Flying RV 8
Anchorage, Alaska
VAF Dues Paid for 2022
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Old 01-23-2012, 09:59 AM
ctbecker ctbecker is offline
Join Date: Jan 2006
Location: Altoona, PA
Posts: 123

I'm not seeing the pictures. What am I doing wrong?
Charlie Becker
N464CB. RV8A
Certificate Issued
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Old 01-23-2012, 06:09 PM
Lars Lars is offline
Join Date: Nov 2005
Location: Davis, CA
Posts: 1,195

The ACK E-04 is $547 at Aircraft Spruce. Has GPS input.
Lars Pedersen
Davis, CA
RV-7 Flying as of June 24, 2012
1200+ hours as of May, 2022.
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Old 01-23-2012, 11:18 PM
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Flyin'Bryan Flyin'Bryan is offline
Join Date: Nov 2009
Location: Littleton, Colorado
Posts: 271
Default Maybe and maybe not - some food for thought

Originally Posted by dbuds2
Got my ACK-406 from Van's and after lots of reading and searching like you're doing, I'm mounting both the ELT and the anntennae on the outboard rib of my right wing. The stiffness from the skin and spar satisfied me for the mount of the ELT and the anntennae should always have visiablity to the sky thru the fiberglass wing tip.

Originally Posted by flyenforfun View Post
The antenna will function fine without pointing vertical
Hello all. I periodically see posts about ELT and/or antenna placement , and I thoroughly appreciate the fact that I will also one day have to figure out where to install mine when the time comes. What continues to bother me, however, is how some of you are choosing to install the ELT antenna in one wing or the other.

At this point I have to put on my hat of 26-years of experience with the Colorado Wing Civil Air Patrol as a check pilot, instructor pilot, and search and rescue mission pilot. As such, I have devoted years to training Colorado search and rescue pilots and aircrews in the art of electronic direction finding, and I would like to enlighten everyone about some things in hopes that you will find a different location to place your antennas other than the wings. My intent is not to hijack this thread, but to provide information in the interest of safety, and to ensure the best possible outcome should the unlikely event occur where you need to rely on the ELT to save your life or that of your passengers.

Basically, the most common accidents that occur are stall/spin accidents close to the ground. I have unfortunately seen with my own eyes the kind of destruction that occurs to the airframe when this happens. One wing or the other is typically completely demolished depending on several factors, including the direction of rotation of the spin. The opposite wing is usually thrown clear of the wreckage and is also very badly damaged due to impact. In almost all of these cases some part of the tail is the least impacted part of the airframe, so this is the logical location that you should attempt to install both the ELT and the antenna.

I realize that the sliding canopy of the RV-3, 4, and 8 aircraft presents a challenge in trying to accomplish this. But there is a reason why this installation is always toward the rear of the airplane in production aircraft, and is also the reason why the black boxes are located in the tail sections of commercial airliners.

Lastly, just to provide some insight into the training that CAP aircrews engage in with respect to ELT direction finding techniques, here are some of the training scenarios that they engage in to ensure that they can locate the signal in the shortest amount of time possible:
1. Full system direction finding (both audio and carrier signal of the ELT are fully functioning)
2. Partial ELT operation, including
a. Carrier signal but no audio (Carrier only)
b. Audio but no carrier signal
c. Antenna not vertical (i.e. practice beacons and the antenna are placed sideways or even upside down)
d. Simulated broken antenna or weak battery
e. Antenna covered by metal or snow, etc.
f. Reflective signals

And that is just a few of the scenarios that are utilized for training purposes. The folks that are proficient in these skills are quite excellent at tracking down an actual ELT location to within a few feet or less. In fact, in Colorado, if a fully functioning ELT is being heard, the average amount of time it takes to locate the ELT is about 3 hours. If your antenna and/or ELT is damaged, or the battery is weak, it may take much longer to track you down.

So I guess the moral to my story is that if you have the ELT antenna installed in one of your wings, please get it out of there, and endeavor to relocate it as far aft in the airframe as possible. I am intrigued by some of the pics of the side mounts inside the fuselage, and I think that this is a much better installation location than in the wings. Just my 2 cents.
Be safe.
Bryan Raley
Building RV8
EAA Chapter 301
SportAir Workshop Graduate x 4: Sheet Metal, RV Building, Electrical, and Composite classes.
Tail Wheel Endorsement Completed
Empennage done, Wings in progress, N462AK reserved.

Last edited by Flyin'Bryan : 01-23-2012 at 11:32 PM.
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Old 01-27-2012, 01:07 PM
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flyenforfun flyenforfun is offline
Join Date: Aug 2009
Location: Wilmington DE
Posts: 325

Forgot the question mark. Was asking if it will work fine without the antenna pointing vertical. Called ACK, the recommended only mounting pointing vertical.
Matt Giordano Sr. and Jr.
RV-8 - N861MM
Wilmington, DE
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Old 01-27-2012, 09:22 PM
Canadian_JOY Canadian_JOY is offline
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,553

To add to Bryan's post... There are lots of RV's flying with the ELT antenna under the fibreglass fairing between the horizontal and vertical stabilizers. This is a bad idea, plain and simple. It's not vertical. It's squeezed in between solid metal surfaces which will distort the antenna's radiation patter very badly. Yes, it's good in that it's mounted aft as Bryan has suggested, but that's the ONLY good thing about it. Too many other negatives are associated with this installation location to even contemplate it. Having measured antenna radiation patterns on aircraft the "under the tail fairing" is simply a very good way to stack the odds against your ELT saving your bacon.
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Old 01-28-2012, 07:44 AM
dcasey1 dcasey1 is offline
Join Date: Sep 2010
Location: Friday Harbor, WA
Posts: 46
Default ELT

Dave Casey

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Old 03-11-2012, 04:49 PM
Dan B Dan B is offline
Join Date: Mar 2006
Location: Edmond, OK
Posts: 221
Default AK-451 ELT

I purchased my AK-451 ELT in Dec 2010 from Aircraft Spurce and installed it in Jan 2011. It has a two year warranty. I have done periodic tests about every 3 months. It failed to test in Feb 2012 during my condition inspection. The unit is dead, no indicator test light and no transmission on 121.5.

Lesson learned: Test your ELT on a regular basis, even if new.

Side note: After phone call to Ameri-King, ELT was shipped to them for repair. I have had several conversations with them since shipping the ELT. English is not the first language at the Ameri-King phone number. Communication has been difficult with the personnel at Ameri-King due to a language barrier. They will not let you talk to a supervisor, you can only e-mail the manager at the company address. Aircraft Spruce has contacted them on my behalf to get the unit returned. Supposedly, unit was shipped back to me Mar 9. Something doesn't smell right here!
Dan Burdette
RV-9A, IO-320
Skyview, Garmin GTN750xi, TT Gemini AP
Guthrie-Edmond Rgnl, OK (KGOK)
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