Pitot tubes cut short

pazmanyflyer · #1 03-29-2017, 10:10 AM

Some wing designs aren't as thick as the RV airfoils so the issue is that the Dynon tubes exiting the pitot were cut VERY short. Still functional as the the owner has used short sections of tubing zipped tied that has worked without issue for years. Common practice on many planes. That's fine and dandy and all but I was thinking of using the quick connect unions such as those sold by Stein. Have any of you used the quick connects for an aluminum to plastic transition without leaks? There is no room to fit my flaring tool on the existing tubing. This is for an RV7 and it is a non-heated Dynon pitot.

airguy · #2 03-29-2017, 10:49 AM

Quote:

Originally Posted by pazmanyflyer

Some wing designs aren't as thick as the RV airfoils so the issue is that the Dynon tubes exiting the pitot were cut VERY short. Still functional as the the owner has used short sections of tubing zipped tied that has worked without issue for years. Common practice on many planes. That's fine and dandy and all but I was thinking of using the quick connect unions such as those sold by Stein. Have any of you used the quick connects for an aluminum to plastic transition without leaks? There is no room to fit my flaring tool on the existing tubing. This is for an RV7 and it is a non-heated Dynon pitot.

I did what you are proposing with the brass compression fittings and they have worked fine. I cut the tubes fairly short and installed the plastic tubing and wiring with about 18" extra length in the wing secured with a tie-wrap, accessible through the inspection port. To remove the pitot from the mast I just open the inspection, snip the tie-wrap, remove the 4 screws holding the pitot head from the mast, and pull the whole thing down with my service loop of plastic line exiting the bottom of the mast. Easy peasy.

pazmanyflyer · #3 03-29-2017, 01:14 PM

Thanks for the input Greg. Here are the short tubes as described:

I was thinking of one of these.

airguy · #4 03-29-2017, 01:38 PM

All you can do is try it and find out. I can see your issue with regard to not flaring the tubes, but the push-on fittings and the compression fittings can both be used without flaring the tubes.

For what it's worth, I recently had one of the push-on type fittings fail on me and dropped my airspeed indicator in flight. To be fair it was not one of the higher-grade push-on type fittings, it was a cheapo from the hardware store.

AX-O · #5 03-29-2017, 01:54 PM

The old Dynon pitot tube had a problem that was discussed here to great detail. Out of those failure/discussions came out a new design. The folks that had bought the old pitot tube were compensated by receiving a new pitot tube (new version). In order to get the new pitot tube you had to cut the lines off the old one and send in a picture of the lines cut.

Looks to me as that could be a possibility for the lines on your pitot tube to be that short.

If it were me;
1) I would check that the version you have is not the old version. If it is, I would research the know issues with the old version and understand the limitations.
2) I would slip a rubber hose over those with a clamp and move on.

airguy · #6 03-29-2017, 02:16 PM

Quote:

Originally Posted by AX-O

The old Dynon pitot tube had a problem that was discussed here to great detail. Out of those failure/discussions came out a new design. The folks that had bought the old pitot tube were compensated by receiving a new pitot tube (new version). In order to get the new pitot tube you had to cut the lines off the old one and send in a picture of the lines cut.

Looks to me as that could be a possibility for the lines on your pitot tube to be that short.

Forgot about that, good point...

lr172 · #7 03-29-2017, 02:39 PM

Quote:

Originally Posted by AX-O

The old Dynon pitot tube had a problem that was discussed here to great detail. Out of those failure/discussions came out a new design. The folks that had bought the old pitot tube were compensated by receiving a new pitot tube (new version). In order to get the new pitot tube you had to cut the lines off the old one and send in a picture of the lines cut.

Looks to me as that could be a possibility for the lines on your pitot tube to be that short.

If it were me;
1) I would check that the version you have is not the old version. If it is, I would research the know issues with the old version and understand the limitations.
2) I would slip a rubber hose over those with a clamp and move on.

I thought the SB was for the Dynon heated pitots. The OP indicated that his was the non-heated variety.

I used the push to connect fittings for all of my pitot and static lines, including the connection with the aluminum tubing on the Dynon pitot. No obvious leaks and indicators report as expected. Well at least not low, as would be caused by leaks. PTC fittings are usually specified for metal tubing, in addition to vynal.

Larry

pazmanyflyer · #8 03-29-2017, 02:56 PM

Quote:

Originally Posted by lr172

I thought the SB was for the Dynon heated pitots. The OP indicated that his was the non-heated variety.

I used the push to connect fittings for all of my pitot and static lines, including the connection with the aluminum tubing on the Dynon pitot. No obvious leaks and indicators report as expected. Well at least not low, as would be caused by leaks. PTC fittings are usually specified for metal tubing, in addition to vynal.

Larry

Correct Larry. Unheated pitot tubes are unaffected.