Full flaps

Continuing on with avionics and cockpit wrap-up, I had to install a microswitch that tells the angle-of-attack (AoA) computer when the flaps are down. Flap deployment changes the coefficient-of-lift curve and so for the AoA computer to work properly, it needs to know when the flaps are down.

Where the flap-down switch resides

The only place I could think of for the switch was right at the front of the flap arm, which is at its lowest point when the flaps are up. I thought I’d do something really spiffy and adjustable…

Flap-down switch, first attempt

…but that didn’t work so well because the bracket (dark grey thing with the black switch attached) was too long and interfered with the elevator pushrod.

Flap-down switch finalGoing back to the drawing board, I put a 90-degree bend in the bracket and rotated the switch so that it’s activated by the flap arm clevis. Works great, and there’s enough play in the switch that I can adjust it later if necessary.

Turns out that was the easy part. This switch grounds a wire coming from the AoA computer, so I had to run a wire from it to the central ground block in the elevator pushrod tunnel. That took most of an evening, but it’s done and the AoA computer now shouts “flaps” through the intercom when the flap-down motor is activated.

Flap motor installed

And here’s the installed flap motor with a Deutsch DTM connector all ready for plugging in to flap power and position sensor inputs for the GEA-24 and GAD-27.