MGL RDAC

[tmobbs]

The MGL RDAC has printed on it that it must be protected from engine fluids, heat, moisture, excessive vibration etc.

I asked the UK dealer for MGL (Paul Sistern of Parts4Aircraft) how he would suggest we do that, given that the RDAC has to be on the engine side of the firewall. He suggested mounting it in a moulded plastic food storage box. In Tesco (a large UK Supermarket) I have found a 900 ml food storage box which says on it that it tolerates -20 degrees C to +120 degrees C. I am thinking about mounting the RDAC on the lid of this, on the firewall, so as to act as a kind of shock absorber, and then fit the base of it as a removable cover, using the flaps on the lid to retain it. Of course I will have to cut various holes in the base to take the various sensors to the RDAC, so it will no longer be air- and fluid-tight, but it should be better protected than if there were no such cover.

Has anyone tried anything similar? If not, what other precautions have you taken to protect the RDAC from engine fluids, heat, moisture and vibration? Or has it been your experience that the MGL RDAC is so robust that it doesn't require any special protection?

Tim Mobbs
Sonex #1555 Aerovee #0672
Bungay, Suffolk, England

[MichaelFarley56]

Great Question Tim.

I've persinally never seen an RDAC mounted with a protective cover but I certainly think it's a good idea. Just another added level of safety!

For myself, my level of protection was simple mounting location. I tried to mount the RDAC on the firewall where it was nowhere close to the exhaust or any large fluid lines. I see a very common location for people is now on the upper firewall, well away from heat sources or other possible sources of contamination. Knock on wood, thus far I've had no issues.

In fact, I don't think I've heard of anyone having RDAC issues. I do think it's a robust piece and can handle the environment inside the cowling without issue.

[Brett]

Mine is mounted direct on the firewall with now protection whatsoever. Has worked brilliantly since its installation and has shown no signs of any form of deterioration or heat stress. I have no plans to change its position.

[mike.smith]

I started to make a fiberglass box:
http://www.mykitlog.com/users/display_l ... 328&row=56

But then I realized a few things that made me stop:
1. All the wires going to the RDAC will need to penetrate the box or its cover. No small task, and a potential way to pull out wires accidentally if threaded through the cover.
http://www.mykitlog.com/users/display_l ... 290&row=44
2. All the RDAC wires enter the device from the side. With a box in place, that makes it very difficult (at best) to install the wires. Even without a box around it, getting around the engine mount, inserting the wires, and securing them with their screws, was sometimes a very frustrating task requiring numerous tries.
3. I mounted my RDAC at the upper left (pilot-side) of the firewall. Center photo, upper right, is the RDAC:
http://www.mykitlog.com/users/display_l ... 3251&row=9
It's far away from any of the bad things in the engine compartment. The only thing I was worried about was rain getting past the cowling and to the RDAC, but my cowl is pretty tight, and I use a canopy cover that covers that area. If I was still worried, all that would be needed is just a shroud over the very top of the RDAC, to let water fall off to either side of the unit rather than onto it.
4. A fully enclosed box was going to retain heat like a greenhouse; no air flow.

70 hours on my airplane now, and not a hiccup from the avionics.

[fastj22]

141 hours on my firewall with no box. No issues.

[peter anson]

I did pretty much what your dealer suggested. It is mounted on the upper left of the firewall (see photo).

It's a really tight squeeze behind the 3300 engine. The lid is mounted under the board and the main part of the box fits over the board and is held on with a cable tie. There are cut-outs at each end for entry of the wires, and with 12 thermocouple channels that's lots of very stiff wires. I have had no problems with it but it was a troublesome fit. You'll have more room with the Aerovee, but I think Mike's suggestion of a lid to protect the board from rain, which could also act as a heat shield, should give adequate protection.
Peter Anson
Sonex 894
190 hours