From the photos it's hard to tell how far aft of the bulkhead the ELT is mounted. Since your antenna location isn't stated it's hard to know where the coax cable will be routed. One wants to ensure the cable can be routed and connected to the ELT without an excessively tight bend radius and that the cable, once in place, won't chafe against the aft baggage bulkhead cover or similar hard surfaces. Ditto for the control cable.
The mount looks plenty stout. It could be stiffened even further by adding some stiffeners, in the form of 90 degree angles bent from sheet stock and riveted in a vertical orientation to the arm of the mount which projects downward on an angle to the lower attachment point. Stiffening this arm will reduce flexing of the mount.
Are you planning on cutting lightening holes?
My thought was to use thumbscrews to attach the bulkhead panel. I thought this location would be an improvement over the battery area that seems to be popular.The older I get the more I realize that nothing can be easily be accessed through the aft baggage compartment. In your proposed location, in the event of an off-airport landing, you would not have easy access to the ELT. One would have to crawl in back with a screwdriver and remove the bulkhead panel to arm or remove the ELT. If injured this could be challenging.
I would move the ELT 12 inches forward and place it in front of the bulkhead panel, on the top right hand side of the baggage hat shelf. Cable routing would be identical. You would eliminate the weight of the mounting bracket, provide easier access, and allow for a visual inspection.
MD
+1 on the lightening holes.
How about the thickness of the material? Maybe .032" 2024-T3 with flanged holes. Every ounce counts!
Try bending it from a single sheet. . . you already have a great template.
Got'cha, Mel. Going with the right arm rest area for antenna. Will need to pass through that bulkhead. My understanding is the possibility of cutting the cable on impact. What about running it through an additional tubular sheath where is passes through the bulkhead?When running your ELT antenna cable, do NOT run it through bulkheads. Run it around them.
In the event of a crash if the cable is running through bulkheads, the bulkhead may be distorted and cut the cable.
Tried bending the .064" with a large radius. Split at bend. Gave up and went to angle stock.
Critique my ELT mounting
91.207(b): Each emergency locator transmitter required by paragraph (a) of this section must be attached to the airplane in such a manner that the probability of damage to the transmitter in the event of crash impact is minimized. Fixed and deployable automatic type transmitters must be attached to the airplane as far aft as practicable.
Note: The reg says practicable not possible.
I have mine under the vertical stab in the open space between the left and right horizontals. As for ease of access, remove the fiberglass fairing for mx or in an actual emergency, break the fairing to gain access if time is critical. Antenna is mounted just forward of the vertical stab, 18" cable run. My understanding is that aircraft tail areas often survive more intact than cockpit areas. Dan from Reno
Yup. I know better. Got excited and didn't check the grain.Bending thicker aluminum, you almost always have to bend perpendicular to the grain. Sounds like you might have tried bending with the grain.
I was going with a mount like yours but was concerned about the vertical orientation of the saddle. Seems like the most common stress is hard landings which induces the load on the straps and clasps.
My thought was to use thumbscrews to attach the bulkhead panel.
It's behind the last baggage bulkhead. Your point about the difficulty accessing this area under the best of circumstances does make one consider the difficulty of accessing after bending the plane and possibly limiting injuries.That sure seems to eat up a bunch of useful baggage space. Seems like there has to be a better way. I still have the old style unit and it is pretty slim and even mounted low it sometimes gets in the way of putting a bag back there.
Remember that when you put stuff back there you are reaching over the rail, around the canopy, and holding the seat back forward. It is not fun trying to jockey a bag that ways 10 or 15 pounds at arms length one handed to get it past an ELT.
Probably the same in the -8. 5 each #8 stainless steel screws with a flag head should serve the strength requirements. Seems like they preform as shear and not tensile in this panel.Pretty sure the bulkhead is a structural part of the RV-4 airframe. It needs to be secured with structural fasteners.
Another ELT question I have concerns the bulkhead BNC fitting I am using to mount my antenna on. Should it be in direct contact with aircraft structure aluminum, or should the bulkhead fitting have non metallic washers to insulate it from the structure? I was thinking it should be in direct contact to give the antenna a 'base plate' for better transmission, but the BNC bulkhead fitting came with a rubber washer so it made me think.
It's behind the last baggage bulkhead. Your point about the difficulty accessing this area under the best of circumstances does make one consider the difficulty of accessing after bending the plane and possibly limiting injuries.
I just took another look at the pictures and you are right. It is under the baggage floor. Is access to the ELT required?