I’m installing a regulated Garmin GAP 26 pitot tube with AOA on my RV-8. I know a lot of you have installed your pitot tubes behind the spar and that it works fine there. But I’m concerned about tie down chains hitting the pitot tube if it’s there. I was thinking about attaching the pitot tube mount to the inspection plate for the stall warner in front of the spar so that the pitot tube will be ahead of the tie down ring. That’s in line with the instructions, which say to put it on an inspection plate in the forward 25% of the wing chord. But if I go that route and don’t put holes in the spar web for the pitot and AOA lines, then I will have to run those lines outboard a few bays and then down through a lightening hole in the spar and then back inboard through the designated holes in the spar. Has anyone gone this route or see any problems with this approach?
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Pitot location and tie downs
- Thread starter Ben Ellis
- Start date
Crash'nF16
Member
I upgraded my pitot from the stock Vans to the Dynon heated AOA tube and put it outboard of the bell crank. I have found I can either park far enough forward or aft of the wing tie down points in a given spot to make an angle where the chains or rope runs in front of or behind the pitot tube. If I park aft that usually means I have a very short run from the tail tie down though. Sometimes the tail tie down chain isn't long enough to reach my tail if I park forward of the wing points, which is when I'll push it back to park aft of them.
Too many rivets and too far outboard - will be difficult to change the pitot head if ever required.
I would certainly go inboard of the tie down rig - tie downs always seem to go outward - but pick up the first 3 spar rivets just inboard of the rib and add a couple more rivets at the back. I believe that is what was shown in details that came with my anodized aluminium mast.
I would certainly go inboard of the tie down rig - tie downs always seem to go outward - but pick up the first 3 spar rivets just inboard of the rib and add a couple more rivets at the back. I believe that is what was shown in details that came with my anodized aluminium mast.
Just another data point
The Gretz mast is designed to be removed. Replacement of the pitot tube is a few screws. The pitot and mast come out. Probably requires replacement with another Dynon tube, but it does come out.
Actually all AN5812-style pitot tubes should be physically compatible, i.e. any teardrop-shaped pitot tube ought to fit.
I ended up installing the pitot tube on the inspection plate forward of the spar, which puts it within all of Garmin’s position specs. Now I don’t have to modify a skin or worry about interference with the bell crank or tie down chains. I can also easily remove it if needed. I didn’t route the pitot/AOA lines until the conduit was attached, just to make sure I could rerun the lines if necessary. I added RTV where the conduit contacts the spar to prevent future abrasion and used a sticky zip tie mount to hold the conduit in place at that location. I’m going to install the temperature controller on the back of the bell crank inspection plate and run the power wires to the pitot tube through an existing hole in the spar in the adjacent rib bay because they are too short to run through the conduit. I’ll have to remove the quick disconnect connectors the wires came with to fit it through the spar, and will probably install a Deutsch connector in its place.
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ddj232
Member
Hello, I know this is a year old post but I am thinking of mounting my mast at the same location that you used in my RV-8. Just curious if you had any problems making the connections to the pitot tube being further outboard. I have the same routing for my pitot and AOA tubes that you show. Any pics of how you made the connection to the pitot tube? I like this location but it seems a bit troublesome for the connections.
Don
No I have never had the pitot tube touch the tie down and I have it on the inspection plate.
My avionics shop had me mount the regulated Garmin GAP 26 pitot on the inspection plate as well. They had me use the Dynon mast.
The other advantages is EASY access for maintenance and the ability to remove the probe completely from the wing when you need to remove the wing just by removing the inspection panel and disconnecting the tubes.
Hey Don,
I did the same thing as Brian Ellis, see his pics at reply #10. Push on fittings with enough slack to reach it through the inspection panel. It’s a tight fit through the lighting hole but doable. I’ve only disconnected it once and that was to paint the plane. Hope this helps. I didn’t find any good pics in my files.
