Rear float fittings

[nichzimmerman]

I did some searching, and it doesn't appear that a definitive conversation has taken place on rear float fittings. It looks like there are four options:

1. Buy weld-on fittings from Avipro (I cant find a picture of what they look like on the fuselage)
2. Copy the main gear fittings (more work and probably stronger/heavier than necessary?)
3. Use the old Beartracks method and fabricate a bolt-on attach fitting
4. Fabricate a weld-on attach fitting

I’ve seen Paul’s youtube video of the float install where option 4 was invoked, and I’ve seen other pictures of option 2. What else is out there? Pictures or ideas? Best practices?

Nic
BH 1217

[Mark Moyle]

I bought the Avipro rear float fittings for the Bearhawk. Bit of a challenge to jig correctly compared to the float fittings I installed in the Pacer. If I had a do over I'd install the trimmer STC'd front gear mount fittings for the PA18 gear on the bearhawk. ($49 from Alaska Airframes) The attached picture is the front landing gear fittings from Alaska Airframes for the PA18 3" extended gear and Maule oleo strut... Bought two sets...one for the gear legs and a set for the rear float attach fittings. I don't have a picture of the float fittings...are easy to jig correctly for welding and easy to achieve a nice looking water tight when covering the fuselage with fabric. I'll look for more pictures.




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[Mark Moyle]

I bought the Avipro rear float fittings for the Bearhawk. Bit of a challenge to jig correctly compared to the float fittings I installed in the Pacer. If I had a do over I'd install the trimmer STC'd front gear mount fittings for the PA18 gear on the bearhawk. ($49 from Alaska Airframes) The attached picture is the front landing gear fittings from Alaska Airframes for the PA18 3" extended gear and Maule oleo strut... Bought two sets...one for the gear legs and a set for the rear float attach fittings. I don't have a picture of the float fittings...are easy to jig correctly for welding and easy to achieve a nice looking water tight when covering the fuselage with fabric. I'll look for more pictures.




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BTW.....I have drawings of the mount.


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[whee]

I have zero float time but it seems to me that the float attachments need to be at least as strong at the main gear attachments. There is suspension on a float plane so the stresses of botched landing or rough water will be transferred to the airframe through the fittings. I wanted my fitting stout.

I chose to copy the main gear fittings. It was very easy. I'll take the minimal extra weight for the added strength for when I screw up and smack down on glassy water.😣

If I could do it over I'd do as Mark M is suggesting and use the $49 fittings from AA.

[nichzimmerman]

I know supercubs are very capable, but I am concerned about installing a fitting designed for a lighter aircraft on the Bearhawk that is approved for 2700 lbs on floats. I would love to be enlightened though.

Also, could someone point me to the correct fitting on the AA website?

[Mark Moyle]

I know supercubs are very capable, but I am concerned about installing a fitting designed for a lighter aircraft on the Bearhawk that is approved for 2700 lbs on floats. I would love to be enlightened though.

Also, could someone point me to the correct fitting on the AA website?

The gear fittings on the Trimmer PA18 gear STC are also part of the oleo strut strut structure. The STC omits the need for the hydrosorb structure which very similar to the bearhawk oleo strut structure....where they connect. (Wish I could have cut out that structure for a flat floor) The gear fittings are substantially stronger when compared to the bearhawk gear fittings.
In the picture..Kent White of TM Technologies. The Tin Man! Is checking the fit for some fairings we're working on... You can get an idea of the geometry for installing floats.. The difference here being the gear fittings are in tension...if it were floats the gear fitting would be in compression.....edit that...they'd be in tension as well.

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[nichzimmerman]

That pacer is a piece of art.

The PA18 fitting idea is growing on me. But I still can't find them on the AA website.

Alternatively, here is a pic (don't remember what website I stole it from) of a bolt-on fitting. Seems like this could be adapted to work with the BH fittings prescribed by the old Beartracks. What is the drawback of bolt-on fittings?

boltfitting.jpg

[Mark Moyle]

That's a picture of Rocket Ron's Bat Pacer. Trying to recall who it was that bought a float plane that was equipped with bolt on fittings...required fabric work and welding to add a new tubing splice to repair the kink in the tube right at the inboard edge of the bolt on fitting. The bolt on uses "U" bolts.... I don't think I'd want a muffler clamp...so to speak on 3/4" .035" tubing.


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[Mark Moyle]

[QUOTE=nichzimmerman;26047]That pacer is a piece of art. Thank you

The PA18 fitting idea is growing on me. But I still can't find them on the AA web site.

You'd have to call Jason at Alaska Airframes.... I'll post up the drawings of the mount. They're made using 4130 square tubing and bushings machined from 4130 rod.

Can send a drawing PDF...reply to moylemc@gmail.com


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[nichzimmerman]

Mark, in your first post the fitting looks like it bends up around the longeron and spreads out around the weld cluster. Was that to strengthen the fitting or just a fuselage repair? I don't see it in the drawing.

Secondly, the bushings have a flange on the inside, which means (I assume) they need to be fabricated on a lathe. Is there a reason they cant be made from plain tube? It would sure simplify things for a guy like me that only has a saw, hammer, and drill press.

[Mark Moyle]

Piper reinforces the mount cluster with a plate. I believe I used .080". Tack welded to the mount and tubing to plate tangent points. Then used a rose bud to heat the plate and hammer form around the tubing. Then welded. I'll have to get you the Piper gear fitting installation drawing. On the bushing....I...um...perhaps two bushings longer than the square tubing is wide. Weld..then cut out the center.


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