Pitot Installations
Posted: Fri Feb 17, 2012 10:13 pm
Just thought I would throw this one out there, FYI!!
Just about finished getting the next "injured bird" back into the sky and
after hooking up the pitot/static junction between wing strut and fuselage I
did the usual leak down test (correct way: hose over pitot tube, hose
plugged and then slowly rolled up and clamped) and it didn't hold any
pressure. Leak determined to be between the pitot tube itself and the hose
attachment inside the wing.
HMMM I said (with a lot of other profanities!!!) No access hole in the
wing!!!!!!!!!! The wing was built, bottom skin installed, pitot attached to
the lower wing skin, lines hooked up and ran out by the lift strut attach
and the wing closed up. Had to cut an access hole in the wing skin only to
find that the "hard" 1/4" nylon line (that we all like to use) had been
attached to the same size pitot aluminum lines using the next size up hard
nylon tube just simply slipped over both alum and nylon to join, with a tie
wrap pulled around the two tubes (pitot and static) to hold in place. Now I
know 99% of you wouldn't do this, as you know it won't seal, but obviously
there is a small percentage that will/have done this so DON'T!!!
If you are using "hard" nylon tube (short of using an actual Parker union
fitting - which you can't do at the tube itself) the proper way to join the
line together is to slip a piece of snug fitting clear PVC (or similar
rubber) hose over both ends to be joined and then, using stainless safety
wire, twist a loop tight around the junction in at least 2 places on each
side of the splice. Then pressure test to make sure everything is sealing
nicely and most importantly: DON"T FORGET TO PUT AN ACCESS HOLE IN THE WING
SKIN, NOW WHILE BUILDING WHEN IT'S EASY, for future maintenance!!!!!!!!!!!
OR the other option is to put the pitot way out in the tip, or the first bay
in from same, were it's up out of the way and in clean air and easy to
access for repairs.
Cheers,
Wayne G. O'Shea
www.irishfield.on.ca
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Just about finished getting the next "injured bird" back into the sky and
after hooking up the pitot/static junction between wing strut and fuselage I
did the usual leak down test (correct way: hose over pitot tube, hose
plugged and then slowly rolled up and clamped) and it didn't hold any
pressure. Leak determined to be between the pitot tube itself and the hose
attachment inside the wing.
HMMM I said (with a lot of other profanities!!!) No access hole in the
wing!!!!!!!!!! The wing was built, bottom skin installed, pitot attached to
the lower wing skin, lines hooked up and ran out by the lift strut attach
and the wing closed up. Had to cut an access hole in the wing skin only to
find that the "hard" 1/4" nylon line (that we all like to use) had been
attached to the same size pitot aluminum lines using the next size up hard
nylon tube just simply slipped over both alum and nylon to join, with a tie
wrap pulled around the two tubes (pitot and static) to hold in place. Now I
know 99% of you wouldn't do this, as you know it won't seal, but obviously
there is a small percentage that will/have done this so DON'T!!!
If you are using "hard" nylon tube (short of using an actual Parker union
fitting - which you can't do at the tube itself) the proper way to join the
line together is to slip a piece of snug fitting clear PVC (or similar
rubber) hose over both ends to be joined and then, using stainless safety
wire, twist a loop tight around the junction in at least 2 places on each
side of the splice. Then pressure test to make sure everything is sealing
nicely and most importantly: DON"T FORGET TO PUT AN ACCESS HOLE IN THE WING
SKIN, NOW WHILE BUILDING WHEN IT'S EASY, for future maintenance!!!!!!!!!!!
OR the other option is to put the pitot way out in the tip, or the first bay
in from same, were it's up out of the way and in clean air and easy to
access for repairs.
Cheers,
Wayne G. O'Shea
www.irishfield.on.ca
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username "rebel" password "builder"
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