Landing gear dimensions

How to keep the Cessna 170 flying and airworthy.

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Landing gear dimensions

Postby Showboatsix » Thu Jul 24, 2008 5:19 am

To all C-170B owners,

I am looking for the dimension (Average depends on weight) between the gear legs, measured on the inside of the gear legs between the four bolts that hold on the axles. (something like 79-80-81 inches)

This could be refered to as the "track dimension"

I am particularly interested on B models after 25612 and those that have the 36 in bend to bend gear (Lady Legs)

Gear Legs Part Numbers used listed below:

P/N 0541118-2 & 0541118-3 - Applicable to S/N 25612 and on

Early Cessna 180 Gear (also used on C-170’s)

P/N , 0741001-3 & 0741001-4

Thanks Dean
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Re: Landing gear dimensions

Postby gahorn » Thu Jul 24, 2008 4:22 pm

I'm not certain why you want that dimension. I hope you realize that it may vary considerably depending upon aircraft weight, wheel toe-in/out (as that will influence the track at rest), and the number of shims, if any, at the GEARBOX (used to adjust wingtip height.)
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Re: Landing gear dimensions

Postby Showboatsix » Thu Jul 24, 2008 7:52 pm

I realize this, however what I am trying to determine is do I have bent gear. Perhaps a hard landing has spread the gear legs out, by bending them at the upper bend. Lets say on the average gear assy, the dimension is 80-85 inches between the gear and mine is 91-1/4 inches (which is my dimension) since Cessna does not publish the degrees of angle for either the upper bend or the lower bend, the only way I can determine is by an average of other aircraft's measurments. If most respond back in the 79-81 inch range, then something is wrong with my set up.

That is why I am looking for this kind of data.

I published the old XP mods gear identification sheet they used to have on their old web site, when they were still in business, I called them about this and all of the "experts" I have talked to simply state.....what ever the part number is the bends should be the same for both gear legs when laid on top of each other.

So since my set up measures 91-1/4 inches, is mine normal or abnormal.

Dean
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Re: Landing gear dimensions

Postby markeg1964 » Thu Jul 24, 2008 10:34 pm

I’m not sure what my measurements are but I have a 170A parked at Twin Oaks. I’d be happy to fly over and let you look at my legs. :wink: I’m sure my 170 has had its share of hard landings both before and after I acquired it so it may not be much help.
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Re: Landing gear dimensions

Postby gahorn » Fri Jul 25, 2008 2:34 am

My B-model, serial 25713, with original lady legs measures exactly 80" between the lower legs, from inside to inside. The fuel tanks are at 1/2, otherwise empty. It is sitting on dry concrete, exactly as it was pushed aftwards into the hangar.

According to the dimensional drawings in The Standard Catalog of Cessna Single Engine Aircraft, the track, from tire tread center to center, all the 170's should measure 86", which makes sense with 6:00X6 tires.
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Re: Landing gear dimensions

Postby ron74887 » Fri Jul 25, 2008 2:24 pm

Dean, I don't know which plane you have but, there was a conversion that had a differeent set of legs installed on it. It was one of the first conversions out there and it is actually a 170HP engine. It has an extremely wide stance. The plane was owned by Berwin Henderson. Ron
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Re: Landing gear dimensions

Postby gahorn » Fri Jul 25, 2008 10:54 pm

Several of the Bolen 172 conversions used wide stance gears. But janetk has already indicated to me he has 180 gearlegs, so that kinda tells us it's useless to give him 170 gearleg measurements.
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Re: Landing gear dimensions

Postby N171Q » Tue Jul 29, 2008 4:42 pm

George,

Can you (or anyone) expand on your understanding about the Bolen gear?

A few years ago Avcon, now the owners of the Bolen STC (renamed to "Bush"?), told me the gear legs specific to that conversion were designed "very similar to 180 gear". I assumed they modified 180 gear legs to interface with the conversion gearbox, but my gear measures lower at the top and is visibily wider than the 170s w/ 180 gear I've seen around here.

without real diminsions, (I've been unable to reach Avcon again), it's impossible to know whether I have sprung-out gear or the Bolen "wide stance gear"? I guess it's the same as Dean's problem.

I've had the legs out, and there are no visible part numbers...

can gear be re-bent to correct angles?
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Re: Landing gear dimensions

Postby gahorn » Tue Jul 29, 2008 5:44 pm

If you're not sure what type gear you have.... then I'd advise you not to try to "bend" it to some configuration other than what they presently are. You have an identification issue, and the best way to address the problem (if any) is to make that determination. You should start with your maintenance records. Those should inform as to what STC is installed. The STC installation instructions should identify the part numbers and source of all parts.

Don't have the installation instructions? Then you must contact the STC holder.

They won't respond? You may be in for an expensive journey. If you can't determine what you have, then how can an IA relicense (annual) the aircraft? You may have to return the aircraft to original status. This is one of the potential problems of modifying aircraft.

IF YOU HAVE A MODIFIED AIRCRAFT.... or IF YOU ARE CONSIDERING PURCHASING A MODIFIED AIRCRAFT..... GET THE PAPERWORK! ALL OF IT! (And even then, there's a distinct possibility that at some point in the future your aircraft will no longer be able to be kept airworthy due to lack of support.)

(There's a reason my motto is what it is.)
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Re: Landing gear dimensions

Postby N171Q » Tue Jul 29, 2008 6:19 pm

good points.

Does anyone know what the diminsions for Bolen gear legs should be?
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Re: Landing gear dimensions

Postby Roesbery » Wed Jul 30, 2008 12:46 am

Many years ago a local 172 had the Bolen conversion done and I remember the gear had a wider ,lower stance. Wasn't long till it had early 180 gear installed and the Bolen gear removed. Made for better prop clearance with the 180 gear.
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Re: Landing gear dimensions

Postby 15A » Wed Jul 30, 2008 1:15 am

WOW!

I find that hard to believe :roll: The Bolen gear legs on my 172 stand tall. Unlike a 170 with only 4" after the bend to the bottom of the leg, mine has at least 6" and maybe more. Won't be to the hangar 'til later this week, but I'll measure it.

You can see on this pic how it looks.Image
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Re: Landing gear dimensions

Postby N171Q » Wed Jul 30, 2008 1:43 am

Here are the measurements from my Bolen main gear when I had the 8.50s on. The plane was at empty weight plus full fuel (1,508#):

Height from ground to gear at belly skin:33"

Height from ground to axle center:9.5"

Length of gear between bends:30.5"

Width between gear legs at axle:???" (Didn't think that was a reliable measurement)

I'd be interested in seeing what the others w. Bolen gear and 180 gear had...
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Re: Landing gear dimensions

Postby mod cessna » Wed Jul 30, 2008 8:18 am

I do not think you can put a cessna gear leg in a Bolen gear box. The bolen gear box is not cessna parts like some of the other conversions. Besides the stc probably calls out the bolen gear pn not cessna gear.
JR N171Q. I know you have bolen gear. You can tell by just looking at it. I thought there were two more bolen gear conversions over by Aero Tech. I would go measure those guys.
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Re: Landing gear dimensions

Postby Showboatsix » Wed Jul 30, 2008 3:43 pm

As my saga continues, I have called every one I can think of, renewed my CPA dues (they will not talk to you with out it), read all of the posts, so the CPA guys told me to call the old XP-MODS guys, they stated (XP Mods) "yes I know the angles of the bends" but I will not disclose them to you, (business secret) but for a MERE $150.00 EACH, I will check your gear legs and tell you if those bends are correct or incorrect! This does not include magnaflux, die penetrating checks, just the ANGLE checks! Lets see.... $300.00 plus shipping and he will tell me my gear are correct or not correct! You know I was born at night.....BUT not last night!

So it appears I am back where I started, normal or abnormal gear legs, I just don't know?

Wishing I had my nose wheel back again!

Dean
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