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Cowl Flap wiring

SeanB

SeanB

Well Known Member
Hello,

I'm considering installation of two Anti Splat Aero Cowl Flaps. For those of you that have installed two of them, did you also use two switches or merge into one? One fuse or separate them with two? Did you have to dig out the honeycomb material in the bottom corners of the lower cowl then do fiberglass layups?

Thanks!
 
I installed two cowl flaps on my -7 to reduce CHTs on climb out. Works.

Used one switch with a flashing idiot light to remind my dumb ass to close it at cruise. Used in-line fuse.
Wired both around the lower cowl to the upper rear right side with connector to firewall wiring.

Didnt dig into the cowl honeycomb corners. The flap plate is flat but the cowl bottom is slightly curved in both axis.
I set the plate corners flush with cowl then filled in middle of plate to match cowl curves. Was up to 1/8" to 3/16" thick at spots.
(also put lightening holes in the plate since I was glassing over the middle.

Be advised, operation-maintenance can be a bugger.
After 300 hours, the wiring across bottom of the cowl can get oily, and one of the actuators has gone out (assume it is from oil intrusion).
 
I used a single switch for two flaps as well. 100 hours and no issues so far. I only need them when OAT is over 95F...which has been common this year.
 
Only one flap and switch for me but if I were to install a second one I would just have one switch. I also have an indicator light. Be aware that the actuator wires are very small and fragile. After a while they broke right at the exit of the actuator and I was unable to repair it. On the second actuator I ran the wire back over the actuator body and used heat shrink to secure it so there would be no flexing or strain on the wire. FWIW
 
Just installed my second one. I have had 2 flights since the second was installed on the right side, one switch. Both flights in August Texas Heat, CHT's running 15 degrees cooler right after runup and takeoff . Had to pinch myself after runup and climb out not seeing CHT's running 420.
 
I installed two in my -7 lower cowl a number of years back. Easy to mount. Just used four screws with nut plates.

Works quite well at cooling on hot take-off days. I can notice a difference in speed and trim when I close them when I start cruise flight. I used one switch, in line fuse.

I also open them when doing a refueling stop. Put the tail into the breeze and help cool down fuel injection lines to make 'hot start' easier.

Used silver metal tape to cover and attach the wires along inner surface of cowl and have a couple crimp-spade terminals near the oil door and a printed label to remind me to disconnect before pulling lower cowl.

I did have an early actuator fail so now I keep a spare on the shelf. Unused for quite some time, but it is there due to a corollary of Murphy's Law. Just like the spare flap motor, spark plugs, Airstop tube, segmented alternator belt etc.

Am happy with them and other A.S. products. Just bought the gust stop.
 
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