Landing Gear Support Wedge - P/N 0441115

[N1478D]

Started hearing a new sound, sort of a rattle, during taxi. By coincedence, the first time I heard it was a week before Reklaw, and I had loaded the camping chairs and tables in the baggage compartment. So that's what the sound was attributed to, the camping gear. Well, after Reklaw and the camping gear was removed, the sound was still there. Asked different passengers if they could tell where the sound was coming from, and everybody pointed to different parts of the plane. (Still teasing one knowledgable 170 owner where he was pointing and he was sitting nearly on top of it - he's now claiming that my landing approach scared him too bad ) Trying to fiqure out where the noise was coming from, started rocking the plane with the wing, kicking the tires - ahh, there's that noise - when I rock the plane with the left tire. Frank's advice was right on the money - hold your finger at the joint between the fuslage and landing gear, then kick the tire and feel for any movement. A little movement on the left, none on the right side of the plane. Removed the Landing Gear Fillet P/N 0511124 and was really surprised to see parts and a bolt laying loose in the area. One of the two support wedges and it's bolt was just laying there, allowing movement of the landing gear. With two 170 guys, Robert and Jim, pushing up on the top of the strut to get the weight of the airplane off the gear, was able to reassemble the support wedge. Checked the other side, and then the three off us attacked a 30 pack of cold beer for some really fun hangar flying with a beautiful Texas sunset - they were wore out from all of the supervision work.

My annual inspections will now include removing the Landing Gear Fillet Plates and checking those wedge bolts, a very simple and quick inspection. A wobble extension will help to test the tightness of the bolts P/N AN4-11A. The wedges do not fit completely flat, so don't get nervous when you first look in there, it's because of their shape. The plane has the P. Ponk mod and all of that looked ok.

[170C]

Glad to hear that you apparently found the problem yesterday. When you pulled the fairing, did you wedge (shim)('s) have one or two bolts? Forgot to mention to you that when I first had the problem & looked inside (mine has two bolts) they bolts weren't safetied! I went ahead and did so which should prevent them backing out. Did you find any cracks in the wedge (shim)?

[JJH55]

All right Joe, now you know that’s not how it all really went down….but I admit, your version does make a better story. You know, when you ask someone if they hear a “rattle” one would think about a pair of shades or a set of keys in the glovebox or something trivial like that. It wouldn’t have dawned on me to think to ask you if you had looked to see if your friggin LANDING GEAR was firmly attached!!! Sheesh. You might want to give some thought about rescheduling your annual a few weeks before Reklaw given the past history.
Sure am glad Frank gave you the tip before your “rattle” became something really bad.
Hey now, there’s a unique concept (170C’s comment) Safety wire!!!!! Duh

Thoroughly enjoyed the evening with you and Robert! Supervising sure is tough work though, had a nasty headache this morning…

By the way, I found a pic of 1478D in one of my back issues of the 170 News (1987).
JJH55

[N1478D]

Frank, neither the wedge or shim had any cracks, all of the parts seem to be in good condition. On each landing gear on mine, there are two wedges side by side with one bolt for each. Neither side of the airplane had safty wire for the pair of bolts. Like Jim and you say, that's the way to go. Not really looking forward to safety tieing in such a tight place though.

Jim, can't believe you would try to wiggle out of not identifying the landing gear flopping around underneath you sound by insinuating that I would embellish a story. Sure do appreciate the help from you and Robert. That would have been hard even with my long arms to pull the airplane down at the top of the strut and put the parts back in. Would enjoy seeing that picture of 1478D.

P.S. The landing gear would still stay in the airplane if both wedges worked loose, but there would be much more movement, and it would surely play havoc on the gear box using the airplane in that condition for very long.

[lowNslow]

Just for info, I got this off the old pponk site a while back (could not find this info on the new site,but it still might be there somewhere).

"Steps to Gear Installation

1) Hoist the airplane.

2) Install your gear in the aft position. This should leave you 1/16th to 3/32nds inch gap between the gear and the front of the bracket. If the gap is larger than this, check the rear portion of the bracket that touches the landing gear to see if it has compression damage due to years of use and striking objects with the landing gear. (Inspect for stress fractures and cracks in any compressed areas.) A symptom of "too large a gap" is a chronic "clunk" when you land or take off. Tightening the shims is only a temporary fix for the problem...the "clunk" usually comes back.

3) Install the wedges and shims so that they do not push all the way in and bottom out. If they bottom out, install an extra shim. (Parts Manual allows more than one shim. You also may need a thicker wedge.) There are 2 sets of shims and wedges holding each set of gear in place.

4) Tap the forward wedge lightly with an aluminum punch and hammer to set the wedge. Screw your 1/4" bolt up snug to the wedge.

5) Repeat this procedure for the rear wedge.

6) Tap the forward wedge again lightly with a punch and hammer to reset the wedge, and again snug up the 1/4" bolt.

7) Repeat this procedure for the rear wedge.

Note: Do not over tighten this bolt...it is there only to keep the wedge from backing out. DO NOT POUND IN THESE WEDGES, THINKING YOU WILL KEEP THE GEAR FROM MOVING. You only will damage the outboard brackets (and keep me in business).

For those of you who are reading this, if you are interested in seeing how your landing gear is installed in your aircraft, go to our web site http://www.pponk.com and click on the picture of the outboard gear box bracket(it takes some time to load...just wait for it. It is worth it. This is an exploded view of the landing gear box."

[lowNslow]

I forgot to post the question that produced the above mentioned procedure.

"By  Steve Knopp

March 15, 1999

Question:
I am installing 185 main gear springs on my 57 180. There is a slight amount of play fore and aft in the outer casting. In the service manual they don't show any shims in this area. If I were to shim the gear to prevent movement fore and aft at the outer casting should I shim the front or rear of the gear?

Answer:
P. Ponk Aviation manufactures a beefed up version of Cessna's outboard gearbox bracket. Many of our parts are purchased by consumers because wedges and shims were improperly installed. They were driven in too far and too hard, damaging the upper portion of the original casting by reforming the metal into a sharp edge, causing stress fractures on the upper portion of the original bracket. In my 30 some years experience, I have inspected hundreds of brackets damaged in this manner.

The wedges and shims are intended to take up any slack and hold the gear to the bottom of the bracket, and will hold the landing gear from moving forward after landing when you set the tail on the ground. They will not hold the gear from moving aft under the load of landing and braking, no matter how hard you POUND them in."

[n2582d]

... one more question though. landing gear wedges (shim), are they required ? this machine has them on one side but not the other which is making her sit a bit funny. thanks mike

Mike,
I'd highly recommend you buy or download a copy of the Illustrated Parts Catalog (IPC) for your plane. You can find a link to a catalog here. When you say "landing gear wedges (shim)" it's unclear to me whether you are referring to the wedges (C-170 IPC fig. 27-4 p/n 0441115) or the shims which are called for on the B model (C-170B fig. 26-6 p/n 0741007). The wedges are necessary to secure the landing gear in the outboard bracket. The shims which piggyback on these wedges may or may not be needed depending on whether the wedges bottom out or not. Cessna calls for a shim (p/n 0541105) between the gear leg and the inboard landing gear attach angle. These shims are to level the wingtips if they are over 3" out of level. Cessna only wants $104 for this shim.

For what it's worth note that the inboard gear attach bolts and washers on your '48 are different than on the later models. The '48 uses NAS 147-34 bolts (superseded to MS20007-34). The A model IPC depicts a NAS 147 bolt but lists it as a AN 7 bolt. The B model IPC shows and calls for a AN 7 bolt. The AN7 bolt has a min. tensile strength of 125K psi, the NAS 147 bolt has a tensile strength of 160-180K psi. The NAS 143-7C washers are countersunk for the radius at the base of the NAS 147 bolt. The current p/n for these washers is MS20002C7.

C-170 IPC Fig. 27

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C-170B Fig. 26

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[mike.bernath]

thanks for the input, mike