Pitot line routing - where in plans?

[Rick_A]

I'm working on the wiring & flight controls and for the life of me, I can't find instructions about the routing of the aft pitot line from the tailcone to the panel base.

I have the complete set of plans on CD and looked in the avionics instructions and FWF instructions. I can't find the routing any where. It seems that it would make sense to install the pitot line before I get all the flight controls installed - assuming the pitot line is routed through the center tunnel.

 

[BigJohn]

Assuming you mean the static tube. My plans from 2011 show this on Page 31-12, Step 2.

 

[Rick_A]

Assuming you mean the static tube. My plans from 2011 show this on Page 31-12, Step 2.

I really do mean the pitot line. I don't have a section 31, only section 31B. In 31B-12 the instructions are for wiring the PTT on the sticks

The static line is pretty simple - it just goes to the Skyview ADHARS bracket area. The pitot line on the other hand, is from the spinner to the ADHARS. The Aft pitot line is initially installed when building the tailcone. It goes from the Skyview ADHARS bracket area, forward along the J-channel and then left coiled in the tailcone.

I'm trying to determine how the coiled line in the tailcone is routed forward. I can't find a reference to it anywhere.

P.S. I actually purchased the Garmin G3X touch plans. The GMU 22 is mounted using the Skyview ADHARS bracket. The G3X GMU 25 (ADHARS) is mounted under the baggage floor above the AP Servo (F-1206E floor). So both the Pitot & Static lines are routed to the GMU 25.

I'm 99% sure that I will install the G3X Touch, so I want to make the modifications now.

 

[Bill_H]

In the old plans, pages 31-12 and 31-13 showed routing the (then) STATIC line from the tail to the instrument panel bay through the system blocks and the little wire way you built. The old D-180 needed the static line run there and the pitot was a short section from the engine back also to the D-180. Later in the Skyview conversion, this long STATIC line became the PITOT line to the ADAHRS in the tail, and the revised static line never leaves the tail section - it just goes into the ADAHRS. If you have more recent plans, that section has likely been revised but the path is the same.

Here's what you want. The PITOT line is just a cutoff end in the instrument bay and follows the path to the rear of the fuselage as mentioned. Coil it up back at the aft end of the fuse until you mate the tail. Then it will follow the path up to the ADAHRS and connect there. You want one long unspliced line from the instrument bay to the ADAHRS when you are done.

When you do firewall forward, the line from the pitot tube will penetrate the firewall and have one connection to the end that you left in the instrument panel bay. This is in 42C and 42D for us guys that "waited for Skyview."

This is probably enough info for you to find it in your revised plans. It goes through the system blocks - which were also revised to accommodate the ADSB wiring and antenna coax. So look for those.

It seems from reading your post closely that your newer plans have you route PITOT tubing in the tail, from the ADAHRS bracket area to the forward part of the tailcone, then coil and leave it there and route foreward once you mate the tail to the fuse. I do not think this is the best idea because that will be routing it underneath your installed flight controls and up that wire way aroun the brake pedals. I think it much easier to route it now in the fuse and coil it at the end of the fuse. I did not find it difficult to lay in the fuse with my head in the tailcone and route the line up to the ADAHRS which is the way we had to do it as I describe above. I think that is easier.

 

[BigJohn]

Oh boy, lots of changes from the D180 days!

 

[Dave12]

Oh boy, lots of changes from the D180 days!

I am completing a new 12 and have it very close to inspection and there are quite a few changes and all of them good.

 

[tomkk]

My page 31b-1 picture shows the aft pitot line from the ADAHRS down the left fuse skin, up through some snap bushings and in the system blocks forward (not sure how it'll fit with all those wires but we'll see). 321b-20 step 4 starts that route. 31b-23 step 2 completes it, I think.

 

[Rick_A]

Thanks.

Bill,Tom, Thanks. Tom, you nailed it on the instruction pages and it confirms exactly what Bill said. I don't know how I missed those steps but I did.

I purposely delayed the OAT wiring thinking that the G3X might provide it's own OAT probe. It does not, the G3X uses the Dynon OAT probe.

Also, now that I know that the G3X pitot line terminates at the baggage bulkhead, I can just remove the pitot line from the tailcone and route it forward. FYI, the G3X package includes a new Static line that brings the static line forward to the baggage bulkhead.