What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Pitot install critique please!

D

dwranda

Well Known Member
Hello all, wanted to get opinions if my Dynon heated pitot install looks good before I carry on. I wanted to get this done before riveting the outer lower skins. Wiring isn't done yet but that's just a matter of installing a connector on the 3 power wires. I was going to use a molex connector for that but I don't have one. I do have molex pins though. Is it OK to use the pins without the plastic connector part and use heat shrink tube over each wire to hold the pins and wires together? I thought I read that on VAF somewhere. It's not like I'm going to take that connection apart frequently.
53nujb.jpg
[/IMG]
1zn1le1.jpg
[/IMG]
 
If there's no reason *not* to use a connector housing, then you should use one (one reason being space constraints, or the like, such as for an electric elevator trim bundle). You have gobs of space here, so I'd say "do it right...use a Molex housing". Not a big fan of Molex, but given the current, it's what I used, also.

Heat shrink alone can chafe if not very properly secured, as well...and then you may have pins shorting to each other.
 
Why not just use a blue butt splice? Remember your wires will be carrying upwards of 20 amps at times, I think a butt splice is the appropriate way to go here. Leave a nice long service loop and you'll never have to cut off the butt splices.
 
Just make sure every connection can be reached with two hands after the skins are installed! Real pain trying to tighten a fitting or connecting a plug with one hand, blind!
 
dwranda said:
I was going to use a molex connector for that but I don't have one. I do have molex pins though. Is it OK to use the pins without the plastic connector part and use heat shrink tube over each wire to hold the pins and wires together?
Click to expand...

It's time for you start buying some connectors and pins. Shortly you're going to need lots of them. Buy a range of Molex connectors. They're dirt cheap.

Go to SteinAir. They stock the lot. Also get male and female pins in light and heavy gauge. And buy a SAT 1023 pin extraction tool. Believe me you'll need it.

And of course you'll need a proper crimping tool if you don't already have one. SteinAir have the lot. Go here:

http://www.steinair.com/product-category/connectors/
 
Paul K said:
Just make sure every connection can be reached with two hands after the skins are installed! Real pain trying to tighten a fitting or connecting a plug with one hand, blind!
Click to expand...

What Paul said. Nice mounting of the aluminum tubing prior to the connection to the nylon, but think about removing the pitot. On my bought airplane, the pitot had 'service loops' in the nylon tubing as well as the wiring. I was very grateful for that when I needed to remove the heated pitot, which was at least three times in the three years before I replaced it with an AOA inclusive mast. Four mounting screws and a little twisting and out it came through the access plate hole by the bell crank.
 
Not sure what kind of access you'll have once the skins are on. I only have one access cover for this area. The pitot is going to go in last so even the bends in the aluminum line are going to be a problem. The adels look nice but unless you can get both hands in there it looks like it's going to be a real problem. Also, make sure you're backing that mast up with a doubler. The kit should have included it.
 
Last edited:
all I will say is this. take your time and do it right. if not it can and will come back and bite you later on. wiring is the one thing that can cause all sorts of problems. if you take your time and do it right the first time you will have less of a chance of problems down the road. and as for butt splices I cant stand them. if your building and airplane build it right and that goes for the electrical system as well. I worked for Boeing as a aircraft test tech and fixed wiring issues all the time. it takes just a little more time to do it right. and you will not see butt splices in their wiring.
I have seen wiring done with butt splices and its a mess.
if I was buying a plane and saw the wiring that had load caring wires that had butt splices I would walk away.
do it right the first time and you will make life easier on yourself if and when you have to work on it.
just my 2 cents take it for what its worth. :D
 
Cleco the skin on and see if you can take it apart and reassemble it again.
Make believe you are on your back on the floor and reaching up into the wing.
 
Max Current for heated Dynon Probe

Pat Hatch said:
Why not just use a blue butt splice? Remember your wires will be carrying upwards of 20 amps at times, I think a butt splice is the appropriate way to go here. Leave a nice long service loop and you'll never have to cut off the butt splices.
Click to expand...

Pat's got a lot more experience than me but I've never seen my heated Dynon AOA/Pitot probe draw more than eight (8) amps.
 
mounting pitot tube

I'm curious as to why most don't mount the tube onto the inspection panel - it is much easier to do &, if you are using a heater module, it can fit on it as well. Most of the installs I do are done that way as it makes any 'servicing' much simpler - just uplug the electrical & 2 x tubes then do any work on the bench, much less effort than working under the wing :D
 
old pete said:
all I will say is this. take your time and do it right. if not it can and will come back and bite you later on. wiring is the one thing that can cause all sorts of problems. if you take your time and do it right the first time you will have less of a chance of problems down the road. and as for butt splices I cant stand them. if your building and airplane build it right and that goes for the electrical system as well. I worked for Boeing as a aircraft test tech and fixed wiring issues all the time. it takes just a little more time to do it right. and you will not see butt splices in their wiring.
I have seen wiring done with butt splices and its a mess.
if I was buying a plane and saw the wiring that had load caring wires that had butt splices I would walk away.
do it right the first time and you will make life easier on yourself if and when you have to work on it.
just my 2 cents take it for what its worth. :D
Click to expand...

What would you recommend instead of butt splices? Any specific type of connector?
 
Butt splice

I'm with Pat Hatch on this. A mil spec butt splice done with the proper crimper in this situation is what I use. Bias against crimp connections is usually based on previous experience with cheap automotive type terminals. I believe 43.13 allows 1 splice in a wire. Leave a service loop and if the appliance needs to ever be replaced, cut it free and use a new butt splice!
 
I used knife splice connectors and covered with heat shrink. Solid physically and can carry good amperage. Not heavy either. Had a loop of wire and secured it up and out of the way, but can be released and handled through the inspection port.

I installed the GAP26 after the wing was all done, so the two hands rule was not easily forgotten.:D
 
Thanks everyone!! Sounds like molex and butt splice are the most common connectors used here. I clekoed the skin on to see if I can do everything with it on. There was no problem at all getting the pitot in and hooked up. The biggest pain will be the 4 screws holding on the controller, but I was able to get to it with a little effort. My pitot mast didn't come with a doubler but I did rivet on a small angle to attach it to the rib for more stability. I don't think a service loop will be needed for the plastic tubes since the easy disconnect is right inside the opening and easy to hook up and take apart.
 
I would add that you might want to double check your range of motion on the bell crank. I had my AOA and Pitot tubes running through a similar support and found the bell crank would rub on the tubes. I made a second bracket that had holes farther from the bell crank which ensured the tubes were low enough earlier for clearance
 
You must log in or register to reply here.
Back
Top