elevator torque tubes ... again

[Buck]

What's the difference between 170A and 170B elevator torque tubes?

[Bruce Fenstermacher]

Besides they are both called torque tubes, everything is different. Well at least the part numbers are different. I just compared the pictures of both for an A and B model and the Pylon Assembly which I would describe as the bell crank where the control rod is connected is different. At least the illustrations of both appears different.

You would also want to compare the length of the tubes and the angle and shape of the rib they are attached to.

I'm always surprised how many long time 170 owners don't know the elevators and horizontal stabilizers are different between the A and B model.

[Buck]

Thanks to george for the info- we have set about having torque tubes fabricated. Shop here in YYZ is doing a terrific job.

[LakeHood170B]

I'm looking for a replacement for my spar-damaged 1952 170B horiz stab, also right elevator/trim tab, and rudder.

I see above that the horiz stab and elevators are different for the B.
What's different about them? Is there an easy way to tell what parts I'm looking at? Is it so obvious that I can tell from photographs of offered parts?

How about the vertical stab and rudder? Are they specific to the 170B? If so, how can I tell what I'm being shown?

[Bruce Fenstermacher]

Comparing the Rag Wing and A model elevator to the B model the changes would be obvious, at least to me. Once I point them out to others that never looked twice at them they go, OH YEA I NEVER NOTICED THAT.

Looking at the trim tab of the Rag Wing and A model the hinge line for the tab itself runs from the rear edge to the rear edge of the elevator. The B model elevator has the hinge line inset into the elevator a few inches and the hinge line of the tab never touches the rear edge.

There are other differences as well and even thought they look similar they are not the same.

I understand that the vertical stab and rudder are the same on all models of 170. Of course the Rag Wing didn't have the dorsal fin (forward extension) from the factory but it can be added according to the TCDS.

[cessna170bdriver]

Also, as I recall, the A-Model elevators don't have the lead counterweights in the forward tip, as do the B-models. Also, if you ever look from behind at an A-model parked next to a B-model, you'll notice the different outline shape of the elevators. I don't know if there's a difference in the horizontal stabilizers or not.

If someone is having a hard time locating a right elevator (trim tab side) for a B, I have one being stored for me in the top of a hangar in Slidell, LA. It needs reskinning (due to a broken tailwheel spring before I bought the airplane), but as far as I know the internal structure is sound. I found a new old stock elevator at a good price (it was 1984), so I never bothered to fix the old one.

Miles

[Bruce Fenstermacher]

Miles

As I said the elevators and stabilizers at a glance look the same but they are not.

The shape, whether they are weighted or balanced the trim system and elevator hinges and positions are all different. There may be some common skins and ribs between the different stabilizers but I think even those are different.

Bottom line you can not intermix any assembly of the horizontal tail surfaces with any other assembly between an A and B model.

Now changing the entire assembly of horizontal stabilizers and elevators may be another story. I know of at least one A model and possibly two that have the entire B model system installed.