The International Cessna^® 170 Association

Thanks guys!

Thanks for all the responses. Years ago the airplane had a wing replacement, so I'm now thinking it may be at the strut.

Danwaters wrote:Thanks for all the responses. Years ago the airplane had a wing replacement, so I'm now thinking it may be at the strut.

There is no adjustment at the strut. You have the correct strut or you don't.

You have a B model and therefor you need any B model strut and perhaps even early 172s might be the usable. You wouldn't want an A model strut as it is shorter and you'd have no dihedral on that side.

Bruce Fenstermacher wrote:

Danwaters wrote:Thanks for all the responses. Years ago the airplane had a wing replacement, so I'm now thinking it may be at the strut.

There is no adjustment at the strut. You have the correct strut or you don't.

You have a B model and therefor you need any B model strut and perhaps even early 172s might be the usable. You wouldn't want an A model strut as it is shorter and you'd have no dihedral on that side.

There was an airplane at the 1996 170 Convention in Alabama (I forget whether it was an A or a B) that actually had a B-model strut on one side and an A-model strut on the other. I don’t know how it flew, but it sure looked odd.

GAHorn wrote: ↑Mon Oct 18, 2021 11:51 pm The early gear can be swapped left/right…but after 170B, serial 25612, the so called “lady legs” became the standard and they are not interchangeable…they are “handed”, different PNs.
The B-model used longer struts which imparted dihedral (almost 3-degrees), so if an A-model strut were installed on one side it would remove the dihedral from that side.

Miles is correct, AM960 washers placed beneath the inside end of the landing gear leg can be used to level the aircraft. The wingtips should be level within 3”. The Cessna 100 Series Service Manual, 1962 and Prior, Para/Sec 5-6 explains:

9A0C23ED-AD4E-4739-9435-BD2EC5908496.png

Item 34 in the following illustration is the AN960 washer or shim:

45F4FA53-CE6D-45EA-A0A9-6E92C38D2D7A.png

Today I did the following to satisfy myself that the left wing low attitude is a result of the gear position:

1. Spot checked the hangar floor with a 3' level and found it to be very close in the lateral plane.

2. Let air out of the right tire until the level across the seat rails showed level. The axle on the deflated side was approx. 6" vs. 7". The turn coordinator ball also centered up.

3. Measured the wing tip heights to be even at approximately 82.5".

4. Checked the landing gear bolt attachment with a mirror to see if shims (washers) are installed and did not see any gap between the gear leg and the gearbox.

None of this was done in a very precise manner of measurement but it all seems to add up to uneven gear, either bent or in need of shimming (or both).

Questions:

1. Are these washers installed over the gear attach bolt (this is what it appears to be in the IPC) or in some other way under the gear leg?

2. What would be the process to re-shim? Seems like you would have to lift and cradle the fuselage which almost certainly not worth the time, trouble, and expense just to level it on the ground.

Thanks,

Bob

Bob,
The shim goes between the leg and the inboard gear bracket, p/n 0713495-6. Obviously, the weight needs to be off the gear to install the shim. Enter the shim part number -- 0541105 -- in the search bar to find out more about these shims. If you do add or subtract shims, follow this good advice given years ago:

n4517c wrote: ↑Tue Mar 25, 2003 12:31 pm One easy way to strengthen the gear attachment is to replace the original AN365-720 nut with the heavy version of AN363 all metal locknut.
The heavy AN363 takes an 11/16 wrench. It has an axial strength of 18,300 pounds and is 25% stronger than a AN365. You end up somewhere between the origional and P Ponk and the nut costs less than a buck.

This probably won't help you as there is no need to remove both gear legs but The Landing Gear Works has some measurements to compare gear legs -- to see if you have a tweaked gear leg.

Hi Gary that’s great thank you.

Just so I am completely clear these washers would go on the attachment bolt between the gear leg and the inboard bracket? I cannot see or feel any gap beneath the gear leg so I assume there are no shims.
Thanks,

Bob

I have used a self-leveling laser level in situations like this. It takes all the guesswork out of it. Place it in front of the aircraft at the height of the axles. Remove air from one tire until the laser beam hits each gear leg at the same point. Then, check across the seat tracks with a level or point the laser through the windscreen at the forward spar attach bolts. Gear legs are not always perfect. I have seen a brand new set of titanium legs that were 1/4 inch off when checked with the procedure mentioned in the post above.

Hardest thing to do is supporting the aircraft on one gear. As the P-Ponk Gif suggests unload the gear, loosen the wedges, remove the gear attach bolt, support the gear leg so it doesn’t try to stretch the brake line. Place the spacer (washer) underneath the gear attach point (best to prime the steel washer) inspect bolt for any surface defects (good time to replace it), reattach bolt, torque with new self locking tall nut. Then tap in the wedges to snug up the gear in the outboard fuselage gear bracket.
On annuals I check the wedges for looseness and the attach nut for tightness, just to ensure no necking is occurring to the gear attach bolt as my landings are somewhat a work in progress. I like the idea of a laser level and have one but I also find a six foot level is almost as good. I would use it across the upper door sills across the fuselage for hand grenade effect.

Be aware that substitution of hardware can be misleading. There are so-called “equivalent” hardware sometimes offered, even by trusted Aircraft Hardware Suppliers…that are not suitable as replacements in certain applications. This landing gear spring attach is one of those that can lead to failure.

Be certain to use only the specified hardware. The IPC lists the nut on this AN7-20A bolt to be an AN365-720C … but some charts (and suppliers catalogs) will offer an alternative MS21044C nut. DON”T do that! Use the specified hardware.



Here’s a 170-B that suffered this failure:

https://asn.flightsafety.org/wikibase/297292

I would be sure to use approved hardware. Never wanted to be a test pilot.

The more I read the more confused I get on this subject.

First of all, I am confident the issue is in the gear; with the cabin level laterally the wingtips are even above the floor, but to do this I have to let air out of the right tire until the right axle is about an inch lower than the left.

The IPC shows 2 shims and a wedge:

1. Figure 26-6 0741007 Shim - Spring alignment. This is shown as a plate inside the wedge at the outboard side of the fuselage gear box.

2. Figure 26-10 0541105 Shim - Wing adjustment (Landing gear attachment). This is shown as a circular washer around the landing gear attach bolt beneath the gear spring and washer.

3. Figure 2604 0441115 Wedge -Landing gear support.

Other than what is implied by their nomenclature, what is the difference in purpose between these inner and outer shims and the wedge?

Thanks,

Bob

When you get the gear off the ground, hopefully you find the gear secure in the fuselage (no leg movement forward or aft). Note where the leg is sitting (the gaps) between the forward and aft edges of the spring in relation to the outboard fuselage gear fitting hole. Some advocate the gear should be positioned aft (maximum gap at the front). The position of the gear in the fitting will effect the gear alignment but I’ve positioned mine in about the middle (final gear alignment done at the axle shims) and have found it stays there.
The gear attachment inboard shim or washer if found its purpose is to raise the inboard end of the spring which has to rotate about the outboard gear fuselage fitting (longitudinal bulkhead) where on the outboard side, the outboard shims and (2) wedges are located. The gear does not precisely fit into that fitting until the spring gear alignment shims and wedges are (as the name suggests) are wedged into the top gap. Their purpose is to fix the gear in its position and transfer the gear loads to the fuselage, when loose, addition load would be transferred to the inboard attachment bolt likely leading to failure, hence checking them at annuals isn’t a bad idea. Any fretting between the surfaces would lead to corrosion, and a costly repair
So in my previous post I mentioned loosening the wedges before putting in the inboard shim, make sense now ?

Hi Jim,

Yes thanks!

Bob