tailwheel rigging

zero.one.victor · Post by **zero.one.victor** » Mon Mar 29, 2004 7:47 am

When I bought my ragwing,the tailwheel steering was connected to the rudder via a pair of small tabs rivetted to the rudder bellcrank,extending aft,just inboard of the rudder cable attach points. A year or so ago,I changed this to comply with the approved Scott 3200 installation drawing: the t/w steering connects to a pair of eyebolts,which also serve to attach the rudder cables to the rudder bellcrank. I left the rivetted tabs in place.
Me & a friend were discussing this,and we got to wondering what the original factory t/w steering arrangement was with the standard tailwheel,which was a Scott 3-24B (AKA Scott 2000). I looked in my 1948 IPC,and it shows the rudder cable attach on the rudder control system drawing. The t/w drawing shows the t/w assembly including chains & springs. But it does not show where the front of the springs attach to the rudder. Does anyone's 1948-1954 IPC show this detail?

Eric

doug8082a · Post by **doug8082a** » Mon Mar 29, 2004 6:16 pm

Eric, My 170B IPC seems to have the same drawings as yours: rudder control system and the t/w assembly, but nothing showing how the steering chains connect to the bellcrank. Odd.

Post by **GAHorn** » Tue Mar 30, 2004 4:07 pm

The Scott drawings are....well,...Scott. I've never been certain whether or not the Scott system of attachment is Cessna approved, or FAA approved on Cessna 170's. I'm fairly confident that Cessna used the Cessna system, and Scott merely issued their drawing as a suggestion. (Sort of like the delicious meals you see on frozen food packages.)

The Cessna system was to use the bellcrank tabs per Fig. 15, page 28 of the B-model IPC. (No illus. of actual springs/chain attachment, but the tabs are shown, and their nomenclature is "Tab-Tailwheel Steering".)

Post by **Bruce Fenstermacher** » Tue Mar 30, 2004 4:34 pm

I actually set my tailwheel up following the Scott method. I was thinking that the eybolt being lower than the horn tabs would help with the steering gyometry.

It didn't.

I switched back to the tabs for this reason. The rudder cables are attached to the top of the eyebolt and the springs below the horn in the eyebolt and pull in the opposite direction. The tension on the eyebolt is sideways and I feel in a short time the hole the eyebolt goes through in the horn would be egged out. Yes the tabs wear but you can fabricate and replace the tab easily. Not so the horn itself and I understand these horns may not be available anymore.

zero.one.victor · Post by **zero.one.victor** » Tue Mar 30, 2004 5:25 pm

That's exactly the thinking that prompted me to re-rig my t/w steering a year ago,Bruce,and to consider changing it back again now. Each rudder cable is attached via a pair of straps--one above & one below the rudder bellcrank. No rock'n'roll on the bolt there. But the t/w steering pulling on the eyebolt down below does introduce some rocking or twisting motion & wear at the bolthole in the bellcrank. So I'm probably gonna go back to the tabs.
George,I have to believe that the Scott 3200 installation instructions ("bulletin No. I-168") is the approved way to do it. The 1960 337 from the TOTAL rebuild ("fuselage assembly--complete, replaced with used airworthy fuselage assembly--complete...") which documents the 3200 installation sez "new tailwheel assembly,Scott model 3200,installed in accordance with Scott bulletin I-168 and this is item 204b of Cessna 170 series aircraft specification No. A-799." The tabs as shown in your IPC (but not in mine) may be the approved arrangement for the standard tailwheel,the Scott 3-24B,but I have to assume that the Scott drawing for the 170 takes precedence for the 3200 installation.
But I'm still gonna rerig mine to use the tabs!

Eric

Post by **GAHorn** » Tue Aug 23, 2005 7:15 pm

This is likely a seriously UN-important matter. But it appears the only method actually ever "approved" was the Cessna method, using the tabs on the rudder bellcrank (for SN's 26505 and prior.)
I've been doing some more research on it. I still can find no approval basis from either FAA or Cessna to use the AN44 eyebolts on a 170 to attach the tailwheel steering springs/chains. Scott's drawing is apparently not approved data...only a suggestion. Scott sells the tailwheel assy (which is approved via type certificate), not the installation paperwork or hardware installation kit, which is not mentioned in the TC or supported by Cessna or Scott. Of course, the use of AN100 cable shackles (to prevent excessive wear on the bellcrank tabs) on my own airplane is probably equally unsupportable from an approval basis. I'm not trying to be the "tailwheel steering nazi",...I'm just trying to settle the issue a bit.
As far as I can tell, the only approval basis seems to be the production certificate which Cessna owned and no STC or other approval seems available for an alternate installation method. (As regards the lack of information in the earlier IPC's, Eric, if your rudder bellcrank had tabs for you to "go back to", I'd suspect that the tabs were probably intended to be used for the same purpose intended for the later airplanes. But I can see why the confusion. As you pointed out, the earlier IPC simply does not show how to attach the steering. The IPC's are not without error in other ways either.)

zero.one.victor · Post by **zero.one.victor** » Wed Aug 24, 2005 5:27 am

gahorn wrote:........................................
I've been doing some more research on it. I still can find no approval basis from either FAA or Cessna to use the AN44 eyebolts on a 170 to attach the tailwheel steering springs/chains. Scott's drawing is apparently not approved data...only a suggestion. ...........

No no no George-- do some more research. Read the 170 TCDS:
" 204(b) Scott model 3200, steerable,swiveling (installed in accordance with Scott Bulletin I-168)". Then check Scott bulletin I-168, it shows a pair of AN42-6 eyebolts at the rudder bellcrank where the steering springs/chains attach.
It's no big deal, but I don't see how or why you state this "is apparently not approved data.. just a suggestion"-- the TCDS spells things out very clearly. Whether or not your installation complies with the TCDS is up to you, and your IA, but just cuz you don't like the eyebolt method doesn't make it "only a suggestion".

Eric

Wed Aug 24, 2005 10:05 am

George I have to agree with Eric that the TCDS does say "204(b) Scott model 3200, steerable,swiveling (installed in accordance with Scott Bulletin I-168)" and so as I read it to properly install a 3200 you would have to follow Scott's instructions.

George you are partially right and may have said this somewhere in the past. Cessna did not obtain the approval for the installation but SOMEONE else did. Notice the single asterisk in front of the number 214? That according to the TCDS instructions what this means.

Post by **GAHorn** » Wed Aug 24, 2005 3:46 pm

I once had a Baron which had upgraded generators on it. The right engine failed in flight and it was discovered that the adjustable "arm" which allowed the generator to be moved so as to tighten the V-belt had rubbed/vibrated against the engine-driven fuel pump's brass fuel line elbow until it broke thru and released the fuel pressure (and sprayed fuel all over the rear of the hot, running engine and down onto the exhaust pipes before blowing overboard. Lucky the thing didn't catch fire.) It turned out that the incorrect "arm" was installed when the generators were upgraded. Apparently because the illustration in the instructions used a different "arm" than the originals. (It used the same arm as that of another airplane. We surmised it was a Cessna. So the best guess was that the installer used those Cessna arms illustrated....not the original ones to the Baron.) The instructions did not specify to remove the Baron arms, they only showed the gen's using the Cessna ones. Cessna arms in a Baron, used with the specified length V-belt will allow the problem I experienced. (Well, actually another pilot flying my plane experienced it. At night. Circumnavigating TRWs.) :{

I'm not questioning whether or not the 3200 is legal on the 170. I realize the original basis of approval is the TCDS and that was obtained by Scott, not Cessna.
I guess my query stems from my not having seen any textual instructions of I-168. I've seen a drawing of a 3200 installation, but no textual description of how to perform it. Does I-168 instruct the installer to remove the steering chains from the rudder bellcrank tabs and install them using AN44 eyebolts? Or is there only an illustration which imply's that the eyebolts might be there already (perhaps even, on another type aircraft?) Eric, you have a copy of that document I believe. Does your copy have text instructions along with a pic?

zero.one.victor · Post by **zero.one.victor** » Wed Aug 24, 2005 5:05 pm

George, the title at the top of Scott bulletin #i-168 sez "installation instructions / scott 3200 tail wheel for Cessna 120,140,& 170 aircraft". An arrown pointing to the eyebolts sez "AN42-6 eyebolt (2) NOTE: install eye bolts at rudder cable connections". There is a indication that these eyebolts, along with p/n 3241-3A spacer & 3241-2 bushing , were available as p/n 3241-1A kit.
Down at the bottom of the page it sez "this method of installation is approved by the CAA. Use CAA repair alteration form #337 and submit installation to your local CAA inspector for approval." The Scott bulletin is dated 4-8-49.
I'll make a copy of this Scott drawing & mail it off to you for your files,George, maybe you can make another copy & send it in for the Assn files. I would think they already have one but who knows.....

Eric

Post by **GAHorn** » Wed Aug 24, 2005 5:23 pm

Thank you, Eric! I appreciate the info! And I'll see that the library gets a copy. I wish I had a gallon of mogas for every hour I've wasted on this subject.

(I mowed my grass runway last weekend. The 9N Ford tractor was certified on leaded gasoline but I've been running it on mogas, and it's loved it. I grabbed my two 5-gallon cans and drove down to the general-store here in Spicewood to get some cheap mogas and ....horrors....the stuff is $2.75 a gallon!

So I drove over to the local airport and bought 10 gallons of 100LL for $2.55 a gallon and mowed my runway with AVGAS!
The old Ford tractor will probably stick a valve now.)

cessna170bdriver · Post by **cessna170bdriver** » Wed Aug 24, 2005 5:47 pm

gahorn wrote:...I grabbed my two 5-gallon cans and drove down to the general-store here in Spicewood to get some cheap mogas and ....horrors....the stuff is $2.75 a gallon! So I drove over to the local airport and bought 10 gallons of 100LL for $2.55 a gallon and mowed my runway with AVGAS!
The old Ford tractor will probably stick a valve now.)

On July 18, 2005,

cessna170bdriver wrote:...I wonder if 100LL were 50 cents/gallon cheaper than mogas, how many would still swear by mogas?

George, it looks like Texas is catching up with California

The day before yesterday I paid $2.819/gallon to fill my saturn with 87 octane mogas. Early last week it was $2.699. California charges extra for adding oxygen to our gasoline that we could just suck directly out of the air.

I haven't flown in 6 or 7 weeks, so I don't know what 100LL has gone to out here; I'm afraid to look! At 3.12 the fuel for a 170 hits $25/hour.

Miles

Post by **Bruce Fenstermacher** » Wed Aug 24, 2005 5:57 pm

Funny tractor story George. Mogas about $2.70 AvGas about $3.40 or worse here in eastern PA. Did add TCP to the tractor?

doug8082a · Post by **doug8082a** » Wed Aug 24, 2005 6:13 pm

N9149A wrote: Mogas about $2.70 AvGas about $3.40 or worse here in eastern PA.

Ditto in MA.

blueldr · Post by **blueldr** » Thu Aug 25, 2005 3:55 am

Speaking of fuel prices:
You guys should see my truck fly!
I have a '78 Ford F-250 with a Nissan Diesel engine conversion.
Diesel fuel is now $3.05 and up. ---- mostly up!
Jet A is selling for $2.69. ---- but you have to have at least a class 3 medical to be legal.

BL

P.S. The truck also has custom tanks and holds 92 gallons. Talk about sticker shock---- I put in $225 worth and it wasn't even full!