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Hi John,
While the attached photos aren't from a Legacy, the concept is still valid. You might want to consider some sub-shelves (or trays) that allow you to mount some of your "black boxes" to assemblies designed around the boxes' sizes, setup in such a way that each tray becomes a "module" that gathers a group of equipment together into a common mounting area. Wire routing becomes easier, you can include places for adel clamps, or holes for wire ties if they're more appropriate for a particular job. Rather than having to build dozens of hard points into your pre-preg shelves, you only need enough to facilitate mounting the trays. You get to build these units outside the airplane, mount all your black boxes, then install the assemblies ready for termination.
These photos show a couple of the trays I fabricated for Ted Noel's IVP. I counted 15 black boxes in Ted's airplane... this is how I dealt with about 1/2 of them. Tray 1 mounts five components, (avionics fan, pressure alarm, encoder, dimmer module, and the fuel flow differential module (FFDM-1)), while tray 2 was designed for 2 identically sized boxes, the AOA computer and the annunciator controler, both from Proprietary Software Systems. (The AOA is now being sold by Advanced Flight Systems, the annunciator is out of production.)
As you can see from the one fabrication photo, the bending was all performed on an inexpensive Harbor Freight brake, and I used an air nibbler to cut the .050 aluminum sheet to size. Nutplates were mounted as required, the components installed, and the trays mounted to the prepreg shelves in the airplane with 2 to 4 AN3 bolts, depending on the application.
There was a discussion not long ago about what kind of support one might expect from Electronics International. The only reason I'm bringing it up here is because of the fuel flow differential module (FFDM-1) on tray 1.... we wanted to share the outputs of the feed and return fuel flow transducers with both the EI fuel instrument and the EAU for the Chelton setup. Initially the engineers from both EI and Grand Rapids Technologies (makers of the EAU) suggested that all we needed to do was parallel the signal wires from the transducers to each instrument's appropriate input terminals. Long story short, that didn't work due to biasing issues with the electronics in the transducers. Several phone calls later found me sitting in the cockpit with an oscilloscope describing waveforms to both Greg at GRT and Ed (I think) at EI in a conference cell call while I added and subtracted components (transistors, resistors, etc) from a breadboard that contained the circuitry needed to get the result we desired as we pumped fuel through the system. That breadboard became a daughterboard housed in the FFDM-1. If you ask me, that was customer service several steps above the norm from both of those outfits.
Anyway, I hope you find the tray idea one worth considering... they really are a nice solution to some of the mounting issues we all run into. Good luck with your project.
<Marv>
JPKleber@aol.com wrote:
Greetings:
I am in the process of installing my avionics shelf; however, I would like to
pre-mount everything with hardpoints and nutplates prior to final install.
For you lucky Legacy builders who are already flying or have the avionics
shelf installed, does anybody have a recommended layout (and list) of all the
gear that resides on this shelf? If so, I would be very grateful if you
would
share it with me (and the rest of the Legacy builders still sanding away).
Thank you,
John Kleber
N83JK LEG2/G
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