180 Gear vs Lady Legs

[GAHorn]

So the answer is to avoid the really nasty sideloads...and only risk small sideloads?

<Edit> Again... certain posts in this discussion have been deleted which has permanently damaged the discussion. You'll have to use your imagination in order to realize the missing-posts proposed that airplanes without Pponk are somehow "better" because they lose their landing gearlegs more easily than the beefed-up Pponk airplanes.

Using that logic, you'll never need a seatbelt in your car.

By the way...you don't have to groundloop to benefit from the mod. Hit a chuckhole or a fireant mound and the Pponk will go a long way to preventing that single bolt from shearing off and dropping your plane onto the ground. That is how the sheared-bolt in the following link occurred...he simply hit a hole in the runway.

Take a look at this: http://www.pponk.com/HTML%20PAGES/groundloop.html

(I'll do my best to quit now.)

[hilltop170]

Last year a similar accident with a 195 on the same runway tore the gear leg off and left most of the surrounding airframe largely intact.

Arash-
You can't really compare what happened to the C-195 directly with our 170s. The C-195 has a one-piece steel truss structure for both gear boxes that goes from one side to the other. That truss is firmly attached to the airframe and will only deform usually after the gear leg has been grossly deformed or failed, usually from wrapping under the plane due to severe side loads. The light 195 gear is usually what is involved with gear failures on 195s. The heavy 195 gear fails less often.

There is no P-Ponk gear mod available for the 195 since there is no place to put it. The steel truss structure already does what the P-Ponk does on the 170. The damage you saw on the 195 is what the P-Ponk mod tries to do for our planes. So in effect, your argument is for both sides.

[ghostflyer]

When I mean Mr Cessna I do not mean poor old Clyde, but the company as a whole. I[ my staff] have refitted and rebuilt torque boxes into fuselarges of Cessna 170,180,185,206 but under the guidance of the factory engineers/repair drawings etc. Please note this torque box design is also used in other Cessna models. The design of the torque box distributes the landing loads evenly . it was explained to me the main bolt is designed to shear out the attachment areas under acute forces and the fuselarge is to take the resultant crash loads. The torque box and the door pillar does give some protection in mishaps. However this main bolt should be replaced every 500hrs or if a very hard landing and skin distortion has occurred. This area should be inspected very carefully on a annual inspection.

[Ryan Smith]

Will you at least put a P Ponk on the little 170?

I should have sent you one of those instead of that DX7.

[hilltop170]

Back to the original subject, I simply prefer heavier gear legs over lighter.

I have flown both styles for many years and just prefer the stiffer gear. However, I probably would have not upgraded to 180 gear on the 170 if a set had not been available. My C-180 had been worked fairly hard in Alaska for many years with skis and tundra tires with lots of off-airport landings since I flew it up from Texas in 1983. So I bought a new set of steel 185 gear from Tailwheel Tom for the 180, then had the 180 gear tested and reconditioned by Jim Hayton in Sedrow Woolley, WA. They were then put on the 170 and I have been thoroughly pleased with them since. I also happen to think the extra few inches of height makes the plane look better as well.

I also had light gear on the 195 which is very flimsy like the early 170 gear. I found a set of slightly damaged heavy 195 gear at an A/C parts store in Anchorage which had been on the shelf for 30+ years that had a very reasonable price tag on them. Jim Hayton was again used to repair and recondition the heavy legs which were put on the 195. I have been thoroughly pleased with them ever since.

The main advantage of the light 170 gear and interestingly enough, the heavy 195 gear, is that they are interchangeable. Since they are symmetrical, they can be used on either side. This makes them more desirable in the fact that all of those gear legs are available for replacement on either side. The later style C-170 Lady Legs, all C-180 gear, and the light C-195 gear are not symmetrical and not interchangeable which makes them harder to find replacements.

I really learned how to fly taildraggers in my 170, with the flimsy light gear, even though I had about 200 hrs of Cub and Taylorcraft time when I bought it. It was a challenge to make smooth landings for probably 50 hours or so. But after that time, I finally "got it" and started making consistently good landings and flew the 170 for 1100 hrs with the light gear, part of which was off-airport in Alaska. I never had any problems with it being the light gear. But again, I prefer the stiffer legs.

So, in my opinion, it really does not matter what type of gear you have on a 170, what counts is to fly it enough to "get it" on making good landings. Once you do that, it boils down to personal preference what type of gear is best.

[Ryan Smith]

Richard,

I never would have guessed your airplane was on 180 gear. As silly as it sounds, the wheelpants threw me off. I understand Greg's use of the 180 gear as it fit his mission profile of a backcountry airplane, but for someone that spends (has in the past, and will when I start flying again) most of their time on either asphalt or reasonably groomed grass, I was simply curious if 180 gear would be overkill. I don't like the lightweight, stock gear on asphalt.

As I very much respect your opinion on the matter, Richard, I have to say I've had a bit of a change of heart in the matter. Maybe the 180 gear isn't so bad after all.

Now to get back to the P Ponk argument ( ), does the use of heavier gear on the airplane induce a different failure point than lighter-weight gear? Obviously hollow aluminum axles are the Achilles heel in any situation, but assuming solid axles or ski axles, is the gear box the weak link with a more robust gear setup? Is it still the gear leg? Axles?

Maybe I should spend Zenda's money so that I don't have to.

[edbooth]

Thought I would weigh in on this P Ponk thing. All the pictures and speculation do not hold much water for me. I installed the kit on my 53 with the lady legs back in 85. I hate to tell on myself, but within about five years of installing the kit, I had two ground loops. The first one was caused by hitting deep water on the runway taking off after a heavy thunderstorm. I slid off the runway and spun 360 degrees in the grass ("missed the runway lights). The only damage was some fiberglass worn off the bottom edge of the wheel pant and grass between the tire and rim. The second one was landing in a very brisk direct cross wind that was somewhat beyond the capabilities of the plane even though I was landing almost diagonally across the runway to cut down on the x-wind component. Again, off into the grass and spun 180 degrees. This time, no damage. Was it the p-Ponk kit that helped, the severity of the ground loop, the grass ???? Guess we don't really know unless I could duplicate those excursions without the kit. I'm thinking it might have helped.

[hilltop170]

Ed-
That was exactly the point of my earlier post. There is no way to tell whether or not the P-Ponk mod will or will not prevent failure in any given situation. Personally, I believe it does no harm, is a good idea, and most likely IMO will protect the gear from failure beyond the point it would fail with no mod. Whether or not damage would be greater with the mod is a moot point.

It is purely the decision of the owner whether or not they want the mod. If someone does not want them, that's their decision and it's ok with me if they don't. I'm not a betting man so I will reduce the risk by using the mod. If you never hit anything or loose control of the plane, you have nothing to worry about either way but any one of us could be the next one so I choose to install the P-Ponk gear mod.

[hilltop170]

.........Now to get back to the P Ponk argument ( ), does the use of heavier gear on the airplane induce a different failure point than lighter-weight gear? Obviously hollow aluminum axles are the Achilles heel in any situation, but assuming solid axles or ski axles, is the gear box the weak link with a more robust gear setup? Is it still the gear leg?

Ryan-
To answer your question, I don't know but again, I think it depends on the situation. The heavier gear will change the loads imposed on the gearbox but I can't say how or how much. It's the owner's choice and I choose heavy gear, I just like the extra stiffness.

[GAHorn]

...

Now to get back to the P Ponk argument ( ), does the use of heavier gear on the airplane induce a different failure point than lighter-weight gear? Obviously hollow aluminum axles are the Achilles heel in any situation, but assuming solid axles or ski axles, is the gear box the weak link with a more robust gear setup? Is it still the gear leg? Axles?

Maybe I should spend Zenda's money so that I don't have to.

The problem isn't the gear box.... it's the manner in which the gear leg is attached without Pponk.

The problem is Archimedean....the AN7 bolt that so many have installed at the upper attach-end of the gear leg. When that wheel starts hopping in the direction of moving underneath the fuselage...the leverage is so great, it pulls the bolt out of it's nut...or pulls the head off the bolt because of the extreme leverage. (The stronger NAS147-34 bolt is what should be there. And it should have a NAS143-7C washer properly installed with the radius beneath it's head.) However that will indeed make the weak-link the common AN365-720 nut, which can strip off the end of the bolt. Pponk helps prevent that by adding a bracket to physically capture the upper end of the gear leg and to spread the load out on the gear box bulkhead.

[buzzlatka]

I figure I ought to reply to this considering the pics are of my airframe.
I put the 180 gear on the 52 170. I liked the results with stiffer gear and better off airport landing characteristics. On pavement it was very stiff and tended to bounce more and was less forgiving for the super smooth landing.
When we did the 180 gear we also did the pponk gear box mod. At the time we were happy we did it because we found some corrosion in the gear box on what we thought was a corrosion free airframe.
What we did not do at the time was upgrade the axles.
When the accident happened I started a swerve to the right. I was slow and just getting ready to put the tail down. I locked up the left brake and was still on the runway when the left axle failed. I was probably only pointed 30 right of centerline. The gear then folded behind and slightly under the fuse. I came to rest on the right side of the runway pointed about 80 degrees to the right of centerline. If the axle had not failed I am convinced I would have either gone off the runway into the dirt at an angle or looped at a slow speed.

In my opinion the 180 gear is not necessary, just something different if you like it. You sit a little higher and the gear is stiffer. I know of one 170 that has bushwheels and does a lot of backcountry landings with the original gear.
The pponk mod was good at exposing hidden corrosion. It completely ripped the floor of the 170 out. I was surprised at how much damage was done to the fuse. The 180 gear was slightly bent the box was intact. If the old gear was still in I'm convinced there would have been less damage to the fuse.
Moral of the story. UPGRADE AXLES first! That is the part that failed and caused all my problems.

[edbooth]

Now we have the rest of the story! Solid axels are a must for piece of mind. Thanks for the clarification.

[Ryan Smith]

Thanks for chiming in here, Stephen. I'm scared for this airplane to have the same fate as yours, as it's got the recipe for the same outcome with regard to landing gear setup. The airplane is due for a new set of tires soon, so hopefully I can catch their replacement so I can see which axles are currently installed. I'm not even sure my father would know. My fear is that you are an experienced tailwheel driver...the people flying my family's old airplane are just learning. I'm not sure if there is any rush to put the 180 gear on the airplane, but it sounds like the old gear may be more forgiving in the end for the current operation.

To muddle Arash's question, there are two types of hollow (steel) axles, if memory serves. The original hollow axles, and the thicker/reinforced "ski axles". I'm curious as to whether the ski axles are any better or worse than solid axles from the perspective of durability. Also, does the use of wheelpants make any difference, or are wheelpants just not strong enough to act as any form of structural support?

With the L-19 being a military airplane, I would assume that solid axles, or at the very least ski axles would be standard equipment on the L-19s. Blueldr has been conspicuously quiet lately, perhaps he can chime in on the matter?

[edbooth]

Ryan, I have only seen three types of axels. The hollow aluminum, the solid aluminum and the solid steel. I'm thinking the steel were the ski axels...you Alaska folks chime in here. The solid aluminum are very robust also, never heard of one of these breaking. These are what I have on mine. As far as the wheel pants, there is nothing structural about them. If you take the axel nut off, you can very easily tell whether it is solid or hollow

[ptporebski]

As a nose dragger pilot I follow this with an academic interest. But I noted the comment about the main bolt recommendation to be replaced every 500 hrs. My question is - does this main bolt recommendation also apply to 172s? I have never heard of a 172 gear failing so I doubt it, but is it something a straight tail driver with leaf spring gear (similar to the 170s) should be aware of?

Thanks for tolerating us fair-haired stepchildren!!