Control cables

Today I was able to spend a few hours working on the airplane. I managed to get all of the control cables installed and routed. I appear to have a control interference issue between the pilot stick and the throttle, and looks like I need to remove half an inch off of the left control stick. However, I need to measure the amount of throw in the aileron pushrods, because it might be that the stick can’t actually move that far horizontally before the bell crank hits its limit.

I was able to connect the prop and alternate air controls, and the mixture and throttle connected. I can’t connect the heat flap actuator until I finish drilling some holes in the bottom cowling.

The routing through the wiring under the panel worked out ok. The prop control was just barely long enough, but I think it’ll work ok. I have loosely connected it for now to ensure I have the right length and throw on the lever. The alt air works great, and the mod from aircraft specialties, allowing the door to open and close, is a nice upgrade.

Controls
Controls
Throttle cushion gap. This is a larger gap than is called for, but I can’t get anything less than this without it being too small of a gap
Behind the control bracket
Under the panel. In the top right you can see the somewhat messy routing of control cables through (actually above) the wiring bundles
Heat flap control
Throttle cable attach. Blue tape indicating this is not final torqued
Mixture control
Throttle and mixture controls

Control Cable Bracket

Tonight I started working on the control cables. Vans sent me the correct control cable bracket, which has an extra hole for the cooling flap, and a redesigned layout. It’s made from slightly thicker material and feels solid. I was able to prime it yesterday, so I mounted it tonight. I also trimmed the alt air cable and the cooling flap cable. The cooling flap cable has a push-button release mechanism, which uses a small ball bearing to create the friction necessary to hold the cable in whatever position it’s set. The instructions have you pull the knob out 6 inches, then cut the end of the cable. At about 5 inches, the ball bearing is exposed and falls out if you aren’t careful. I noticed this and put the parts into a zip lock bag while I trimmed the cable, then reinstalled it. It would be a major pain in the butt if the ball bearing fell out onto the floor, I would never find it!

The cabling under the panel is going to present a challenge for routing these control cables, but I plan to pass each cable between the cable bundles and the mounting frame I built forward of the sub panel. It should work ok, although I’m sure I’ll run into some kind of challenge.

Original bracket on the left, new one on the right
The cooling flap control. Barely visible is the small hole where the ball bearing sits, just above the “2” on the ruler.
The ball bearing, spring, and button which forms the grip mechanism inside the cooling flap control cable handle.

Heat vent controls

Tonight I installed the two heat vent cockpit controls. These are push/pull controls that are mounted on the instrument panel and open the heat vents, one pilot side, and one passenger side.

No real challenges installing these controls. I was careful to ensure I had a 1/16 cushion gap when the vents are fully closed. This will be more critical on the other controls, but it was good practice.

In the process of reading through the plans I made a couple of realizations. One is that I have the wrong version of the control mounting bracket. The version I have is labeled as the updated part number with a -1 at the end, but it’s actually the old version. I emailed Vans to confirm, hopefully I can get a new one quickly. I could just make a new one, but locating the holes would be time consuming. Unfortunately I’m blocked on the rest of the control cable install steps until I have that bracket in-hand.

The other realization is that my panel wiring harnesses are going to be interfering with the control cables. I can probably make it work, but will need to look out for chaffing problems in places where the wiring bundles and control cables are touching.

The control cable collection
Pilot side cabin heat control
Passenger side heat control
The mechanism to open and close the heat vent. These are on the firewall.
Routing of the control cable