It's a good idea to supply cool air to your most power-hungry avionics, so I bought a cooling fan to go with my Garmin radio stack. Well, actually the fan is made by Sandia Aerospace, but Garmin resells it. It appears to be a run-of-the-mill squirrel cage blower with some fancy gold-anodized sheet metal around it to justify the 10x aviation price multiplier.
The fan has mounting flanges along two sides only (not opposing sides either) and one big honking flange sticking out at right angles, which is just weird. It says "Beechcraft A36" on the label, so maybe the Bonanza has some little odd-shaped cranny that it's designed to fit perfectly into. To mount it in my airplane, I decided to build this little mounting bracket/standoff thing out of some Z-channel material:
If I ever need to replace or service the fan I will be laying upside down with the fuel selector valve poking me in the kidneys, so I wanted to make it as easy to remove as possible. Hence, nutplates instead of discrete screws and nuts.
Here it is mounted to the subpanel. Even though it's only attached on two sides, it's plenty rigid and is definitely not going anywhere.
The bracket is blind-riveted to the subpanel from the aft side. Yes, I realize I already used this picture, but since I fitted and installed these two components simultaneously you'll just have to look at it again. Also note that one of the rivets does double duty holding a plastic tie wrap anchor for the wire bundle that runs through here.
In this shot, you're standing on the left side of the fuselage looking to the right across the forward side of the subpanel. You can sort of see how the cooling ports on the fan are semi lined up with the back ends of the avionics trays – this alignment is aided by the standoff/bracket thing, and will make running the air tubing easier. Once I finish wiring the radio stack, I'll run air ducts from the three outlets on the fan to the two GPS units and the transponder, which are the boxes that generate the most heat.
