PPonk STC

[jrenwick]

I'd be curious to know the accident history of Cessnas equipped with the Pponk kit. Anybody have actual statistics?

John

[Bruce Fenstermacher]

Voorheesh no problem. What you think there might be different opinions in the aviation industry?

John I don't know how the data could be kept. You would have to come up with some type or accident rating system to tell if the accident with the Pponk was greater or just equal to one without it. You would also have to know how many accidents and damage, if any, were averted due to the mod.

About the only way I could see would be to take two or more examples of a stock and modified aircraft and crash them the same and compare and no one is going to do that.

[jrenwick]

I was thinking of something simple, maybe just anecdotal reports of ground-loop accidents with Pponk installed, where there was damage to the gear box. Anybody know of any?

John

[GAHorn]

Pponk has very convincing pics/video to help them sell their product. I suggest anyone curious about it go to visit that website.

As for the argument "which is better...to be beefed up? ...or not?..." I consider it to be like the use of automoble seat belts, air-bags, and 5 mph bumpers.... If you need them you're probably saved. But if you have a head-on with an 18-wheeler .....Tell me what speed you are going to hit him and what he's carrying..... and we might predict the outcome.

Most ground-loops are minor and a Pponk can potentially save the airplane. The really bad ones make no difference....both airplanes will take extensive work to repair. Tear out a standard gearbox or tear out a Pponk gearbox...they both need gearboxes and adjacent structure and the Pponk does not add any repair difficulties. (It does, however, add value to the airplane and may keep the airplane from being totalled by the ins. co. if you document it and pay the added premiums.)

voorheesh, (not picking on you, just using your query as a comparative example)... Do you have shoulder harnesses? If you crash and rip them out you will surely damage the airplane more than if you hadn't installed them. Is it logical therefore, to not have shoulder harnesses?

Your mechanic will certainly enjoy greater income from your aircraft repairs when your parking brakes lock-up. (Versus...how much need do you actually find for them? And, even should you utilize them.... do you actually trust them?)

[voorheesh]

I have shoulder harnesses and consider them the most important safety feature after a pilot who is thinking clearly and a well maintained airplane. I removed the parking brake from my 170 but not before the mechanic who did it demonstrated to me that you would have to apply major pressure to get the pedal near the firewall blanket, let alone actually touch it. He then showed me the strength of the little springs that the parking brake handle has to stretch/compress in order to get the parking brake set and he told me you would have to intentionally manipulate the system to get a properly adjusted Cessna parking brake to engage in flight. But, I dont want to start that argument again Please!!!! I am just pointing out that some very highly experienced mechanics don't necessarily agree with us pilots when it comes to these issues. I did remove the parking brake due to the experienced advice I received from this website and I don't regret it because it is one less hazard to think about. After considering P-Ponk, I am beginning to see your point that it wouldn't hurt to beef up the gear in this old plane despite my mechanics protest that I would be adding a "boat anchor".

[jrenwick]

Hardly a boat anchor! It weighs almost nothing, and is quite inexpensive and easy to install (less than 1 AMU, all done). Cheap insurance in every respect, IMHO.

Happy New Year!

John

[GAHorn]

The little springs do not have to move at all to set the parking brake inflight. All that is necessary is to lift the locking lever with the pedal depressed.

[Brad Brady]

The little springs do not have to move at all to set the parking brake inflight. All that is necessary is to lift the locking lever with the pedal depressed.

Which can create a hug problem......which is why I recomend that the parking brake be removed..Just my thought.....Brad

[Green Bean]

Another thought about the P Ponk mod, is that the gear leg is held in place by a 4 bolt secured block, where as the Cessna design is held on by the one main bolt. A few years ago, at King Salmon, Alaska, a 185 was taxiing for take-off, and both main gear bolts failed at the same time (the head of bolts sheared off, (due to age, stress and fatigue). Result was a short low taxi. The aircraft had a history of remote airport operations as well as winter ski operations. If it had the P Ponk kit it would not have happened. Paul Knop (P Ponk spelled backwards) also makes a kit to repair aircraft that have had gear box failures due to ground loops, and other gear box issues.
The P Ponk mod is easy and quick mod to install. It should also be noted that it is George's number 3 item on the list of good modifications to your 170. Good Choice.

[mit]

Another thought about the P Ponk mod, is that the gear leg is held in place by a 4 bolt secured block, where as the Cessna design is held on by the one main bolt. A few years ago, at King Salmon, Alaska, a 185 was taxiing for take-off, and both main gear bolts failed at the same time (the head of bolts sheared off, (due to age, stress and fatigue). Result was a short low taxi. The aircraft had a history of remote airport operations as well as winter ski operations. If it had the P Ponk kit it would not have happened. Paul Knop (P Ponk spelled backwards) also makes a kit to repair aircraft that have had gear box failures due to ground loops, and other gear box issues.
The P Ponk mod is easy and quick mod to install. It should also be noted that it is George's number 3 item on the list of good modifications to your 170. Good Choice.

Better inspections would have prevented the 185 incident.

[Green Bean]

Since it belonged to an Air Taxi, makes you wonder?

[cholzer]

It really does make you wonder. I watched an annual inspection on a C-172 completed, from start to finish, one noon time while having lunch at the local airport restaurant. The owner and the IA never even removed the tie down ropes. Don't know where they went, but neither is around the airport now.

I was approached by the owner of a 1956 C-172 to do a 'quick inspection' for a pending sale several years ago. Did a standard annual, found 17 items that were grounding, including main spar corrosion in the cabin, (poked a hole in the spar with a ball point pen, it was that bad). Gave the list to the owner, and signed the inspection off as C/W, but unairworthy. A week later, the plane was gone. Asked the airport manager if the owner had gotten someone else to work on it? She said a gentleman had flown up from North Carolina with his mechanic, who signed off the 17 items, money changed hands, and the new owner flew it back to NC. I guess God really does watch over fools.......

[GAHorn]

Unless that was simply a "ferry permit" his A/P signed (and faxed, of course) .... Yep, there are some scary things that go on out there, and the odd part is...a lot of folks actually feel good about pulling off one of those stunts.

[hilltop170]

Back to the P-Ponk main gear mod, the inboard main gear bolt head on un-modified gearboxes has been known to fail on Cessnas, due to fatigue, overload, or whatever cause. When that bolt head comes off, your plane is wrecked. The P-Ponk mod will prevent the bolt head from breaking off.

If the plane is abused enough for the P-Ponk modified gear to fail, it will tear out a larger piece of the airplane when it does fail. But, the P-Ponk modified airplane will withstand more abuse before the failure. If the P-Ponk fails, the plane would have already been wrecked if it had not been modified.

Bottom line is: there is no downside to installing the P-Ponk gear mod but there is more risk of gear box failure if the P-Ponk mod is not installed.

[lowNslow]

Question: I do not have a Pponk installed yet but was wondering how they have you install it and provide for level adjustment. Cessna states that if there is in excess of 3 inches difference in height above the ground at the wing tips to install shims (washers) under the gear before installing the bolt.