Tapered Flange Adapter Torque

[N-43121]

I've been surfing the forum a lot lately, but haven't found a solid answer yet to my question. The attached article (from a Luscombe / Cub Club newsletter) is a great discussion of the technique for removal and reinstallation of tapered shaft hub adapters. But I wonder if it is correct for the torque value for attaching the hub adapter to the crank. It says 200 - 225 ft-lbs. That seems too high.

I am using a Sensenich 76AK-2 metal prop on a C85 tapered shaft engine. Does anyone have a technical authority reference for me on the proper torque for the flange adapter to crank installation?

Thanks,

Rod

[Robert Lees]

Re: Tapered Flange Adapter Torque

Deleted due to me providing duff info. Garry is correct below.

[Garry Crookham]

Re: Tapered Flange Adapter Torque

The reference on page 118 is for the 3/8" prop bolts, which are to be torqued to 200-220 inch/lbs.

The hub nut torque is 220-225 foot pounds, per O/H Manual X-30010 page 38 and 39, Propeller Installation, item i.

220-225 foot pounds might seem excessive but it's not, if the hub nut is torqued to 220-225 inch/lb the hub will work on the shaft and at minimum eventually damage the shaft.

Garry Crookham
Tulsa

[N-43121]

Re: Tapered Flange Adapter Torque

Thanks,

I should have checked the "bible" before posting the question. I looked at the Continental overhaul manual and found the info. The 220 - 225 [U]foot[U]-pounds is the corrrect torque for the flange adapter. When I read the article (attached to my first post), it seemed too high to me, but that is the right number.

Thanks for the responses. I should have checked the manual before posting.

Rod

[Robert Lees]

Re: Tapered Flange Adapter Torque

Oops! My misreading of the manual...thanks for the timely correction, Garry; I'll edit my post above.

Rob

[Guest]

Re: Tapered Flange Adapter Torque

The reference on page 118 is for the 3/8" prop bolts, which are to be torqued to 200-220 inch/lbs.

The hub nut torque is 220-225 foot pounds, per O/H Manual X-30010 page 38 and 39, Propeller Installation, item i.

220-225 foot pounds might seem excessive but it's not, if the hub nut is torqued to 220-225 inch/lb the hub will work on the shaft and at minimum eventually damage the shaft.

Garry Crookham
Tulsa

Hi all,

I have we seen an Aeronca service bulletin that describes a different method. Will try to find it later tonight.

Here is my opinion and the experience that I had.

I torqued the bolts to 185-225 inch pound range on by new Sensenich wood prop and new taper hub (yes a new taper hub) according to the Sensenich wood prop instruction that was published at that time.

The result was that hub flange got dimpled around the boltholes where it pulled into the large holes in the prop's hub (the big holes that allow the prop to fit on a flanged crank). I did have the prop bushings in.

After that I stopped using the torque method and used the other method for wood props that was on the old Sensenich sheet which is to basically take the slop up in the prop bolt plus one half turn more to press the wood a bit to provide friction.

I just removed a taper shaft hub adapter from a crank last week that was cracked along the key way. It was on so tight that I could not get it off with a 20 press and medium effort. I actually cut it off to avoid damage to the crank.

I think that they get overtightened and cause that crack and other damage. I have not been tightening mine to 200 ft-lbs but rather use the method that I read. Will try to find a copy.

I do have a metal and wood prop, both on their own hub so I change the prop and hub together ever couple years. I install the hub with lots of anti-seize and some times bee wax as well. It comes off every time. Actually about once a year (even if I do not change the prop) I take it off just to make sure it is free (since 1998).

And I just realized that my overhaul manual is old its a x-30008, has no prop torque section. But that does not change my experience.

Dave

[Guest]

Re: Tapered Flange Adapter Torque

found it!

Champion Service helps and hints #14

I know its not a Continental or Taylorcraft document but it is a manufacturers document (for an a-65 installation) and it is informative.

Dave

[Garry Crookham]

Re: Tapered Flange Adapter Torque

Dave
Hope you can find the write-up, I would like to see how it is tightened. I agree that a lot of hubs are way too tight. Most installers use a bar and pull until they think the torque is correct instead of using a torque wrench.

There is a bulletin on the Sensenich website that gives a couple of methods of installing the prop on the hub. I prefer the method you described of taking the slop out plus one-half turn. The Sensenich bulletin actually gives a procedure on how to calculate how much to snug the nut down after taking the slop out.

Pulling the prop hub off the shaft at each annual is a must if your airplane sits outside and it's a good practice to pull it every couple of years if it's hangared. I've had a couple of hubs that were almost impossible to pull off the shaft due to rust and corrosion. A Stearman owner brought his airplane to me for an annual a couple of years ago. The prop was starting to delaminate and a check of the logs showed the prop and hub had not been removed for 18 years. I had to fabricate a puller to remove the hub from the crankshaft and sent the hub in for ndt and replating. The owner was lucky, the crankshaft wasn't damaged.

Garry Crookham
Tulsa

[Guest]

Re: Tapered Flange Adapter Torque

link to the Champion Service helps and hints 14 is;

http://www.aeronca.com/docs/HelpsAndHints/14/21-Feb-1961/SHH_14_Champion_21-Feb-1961.pdf

I have the file but cannot attach because it is too big 1.01MB but can send to your email address.

Dave