Rudders

[Kyle]

Evening everyone. Just over a week ago we had a Nor'Easter pass thru Cape Cod. My 170B rudder was damaged. It will need both lower skins and the Bell crank replaced. The trusty leather / bungie cord "rudder saver" could not resist the winds.

One of our fellow 170 members loaned me one of his rudders - from an "A" model. Out to the airport we go - anticipating being able to fly in a couple of days to my sons football game on Nantucket...

Slight problem. With one bolt in the top hinge, the middle hinge and bellcrank holes did not line up (about 1/2" - 5/8+" out respectively) because the elevator torque tube was already hitting the lower skin at the aft most part of the notch for the torque tube.

Anyone else found similar issues between A and B model rudders?

[Bruce Fenstermacher]

Can't figure out why the rudder wouldn't fit. Pictures pictures. Most of us are carrying a phone with a camera yet we don't think to take a picture.

I'm curious about "The trusty leather / bungie cord "rudder saver" ". Did you have bungee cords as part of the "Saver". I had to replace a control horn on a 170 and nearly reskin it after I secured it because of a trusty bungie cord "rudder saver" system. Bungee cord has NOT proven to be Nor'Easter proof and I don't recommend their use, even in Texas.

[jlwild]

Kyle, Have you measured the spacing between the two rudder hinges and rudder bellcrank on the damage rudder and compared them to the loaner rudder? If they are different you have a rudder issue to solve. If they are the same, then your reinstall procedure of the loaner may be the issue.

[cessna170bdriver]

I have both new undrilled bottom rudder skins that I bought at a 170 convention auction a few years ago. I don't know whether A and B models have the same part, and if not, which I have. I can check them against the ones on my '55 B-model, and if they are the same you can make me an offer.

[Lopez]

The A and B model rudders are different. The B model elevator hinge line is approximately 1" further aft than an A model. The notch in the rudder is therefore bigger on a B model rudder. You can install a B model rudder on an A model, but you can't put an A on a B. I too learned this the hard way, after I did a beautiful job reskinning the A model rudder.

[GAHorn]

The A and B model rudders are different. The B model elevator hinge line is approximately 1" further aft than an A model. The notch in the rudder is therefore bigger on a B model rudder. You can install a B model rudder on an A model, but you can't put an A on a B. I too learned this the hard way, after I did a beautiful job reskinning the A model rudder.

Well.....there ya' go! 'splains why they have DIFFERENT PART NUMBERS!!!

Thanks, Lopez.

The (rudder) front and rear/aux spars are the same as are the (rudder) bearings/hinges. Lopez,... if one were willing to cut the skins back... any other reason you can think of an A rudder mightn't fit? (I think you've already answered this in the above statement, but I'm asking if any other modification than skins are required.)

[Lopez]

The "bellcrank support" is different between the A and B rudders in addition to the lower skins.

A part number - 0533000-7
B part number - 0533000-13

Other than that, they are the same.

[minton]

The A and B model rudders are different. The B model elevator hinge line is approximately 1" further aft than an A model. The notch in the rudder is therefore bigger on a B model rudder. You can install a B model rudder on an A model, but you can't put an A on a B. I too learned this the hard way, after I did a beautiful job reskinning the A model rudder.

Well.....there ya' go! 'splains why they have DIFFERENT PART NUMBERS!!!

Thanks, Lopez.

The (rudder) front and rear/aux spars are the same as are the (rudder) bearings/hinges. Lopez,... if one were willing to cut the skins back... any other reason you can think of an A rudder mightn't fit? (I think you've already answered this in the above statement, but I'm asking if any other modification than skins are required.)

We need both the "Groan" and the "Can of Worms" added!!

[Kyle]

All, Many thanks for the replys and the offers to assist, here and PM,d. I thought I would post a few pictures.

P1090102.JPG

P1090091.JPG

My Bungie system was designed after reading some posts on our site. If anyone has a better system I would love to hear what it is, and maybe see a picture if you have one.
We have the parts on the way and hope to get this back in action soon...

[Bruce Fenstermacher]

Kyle, there is nothing wrong with your bungee system except as you and I have found out, the bungees you included in it. The system as you have it seems to be sufficient and it is for normal lower winds. Hard to believe higher winds will move the rudder against the stops overpowering the bungees, but it will.

Get rid of the bungees in the system. Go with the simple cheap nylon rope solution George pictured elsewhere. Leather or rubber bra like you have is an option.

[GAHorn]

Here's pics of the way I secured the rudder Gust Lock (after securing the elevators-up/ailerons into-expected-wind with the seat belt.):

[Bruce Fenstermacher]

My opinion is it is not important where the end is secured either in the front like George shows or at the elevator hings. And it is not important whether the bra around the light is leather, thick rubber or nylon rope as in George's example. The key is not to introduce a bungee into the system. Bungee's have to much stretch.

[GAHorn]

My opinion is it is not important where the end is secured either in the front like George shows or at the elevator hings. And it is not important whether the bra around the light is leather, thick rubber or nylon rope as in George's example. The key is not to introduce a bungee into the system. Bungee's have to much stretch.

I agree completely. I only prefer to route it below the elevator because the rope in that position offers additional support to the elevators even if the seatbelts should slip....and if the elevators are locked in the UP position...it's easier than kneeling down to hook underneath the elevator hinge.

Whatever you do...... NEVER attempt to restrict the rudder movement at the counter-balance (top) or the rudder bellcrank (bottom) DESPITE THE EXAMPLES SHOWN IN THE SRAM (Service Related Articles Manual) our dear assoc'n produced! Such methods are virtually guaranteed to damage your airplane!