8KCAB Gear Strut Uneven

[flyingskier]

I have seen for awhile now what looks to be uneven gear struts. The angle appeared to be slightly different between the two, like it was leaning towards the right. Yesterday after a x-wind wheel landing on the right main there was a noticeable change in the camber of the wheel. I am just now learning about the upgraded U-bolt fittings but can not find documentation on them. The only service letters I find are re-torquing them and inspecting the fuselage for cracks. I have attached pictures of the gear post-flight. After pushing it back into the hangar they seemed to go back to a more normal position.

 

[Bartman]

Hello @flyingskier

It looks like you've got a couple of tired old spring steel gear legs. Definitely plan to replace the bent u-shape gear hardware with the bar-and-bolts style of hardware but you will have to choose between buying reconditioned gear legs from Rainbow Flying Services or upgrading to the newer aluminum gear legs from ACA. The aluminum legs are about $7000 which includes new mounting hardware but you'll also have to modify the opening in the fuselage where the gear legs plug into the frame.

 

[Big Ed]

Never seen U bolts like that. Here is what the new ones look like. Order them from ACA. I highly recommend this upgrade. When I researched accidents in Decathlons and Citabrias, failures of the gear attach hardware were common, with the usual consequence being a trashed engine, prop, and wing. Cost is about $300 per side.



I had sprung gear too. The Rainbow Flying Service reconditioned gear legs are good quality and at a very reasonable price. Upgrading the gear legs and hardware is a 1-2 weekend project, and requires no technical skill or unusual tools.

Before you do that, might as well follow the service manual procedure to check if your gear legs are bad. Load to gross weight, lift the tail, roll straight forward 20 feet, and measure the camber. Camber is the angle between the vertical plane of the wheel and the ground. It the wheel leans more than 5 degrees inward (top towards aircraft), the gear legs are "sprung" and should be replaced. That is for my 78 8KCAB, but I assume it is similar for other older variants with the spring steel gear.

From the picture, your camber angle definitely looks excessive, but follow the procedure to be sure. Camber on one wheel can sometimes look out of whack after turning. Here is what mine looked like before I repaired it:



And after:

 

[flyingskier]

Those are the stock u-bolts. Are the upgraded u-bolts even covered under preventative maintenance so that any part 61 certificate holder could do it? Wouldn't you need an a&p? My camber got better after rolling the plane back into the hangar. I'm planning to get the aluminum gear this winter because I could really use the max gross increase.

 

[Bob Turner]

Easy to install, but yes, this is A&P territory. Do what Ed does and find a mechanic who will supervise your work and sign the logbook. And I agree - get those U bolts in the recycling ASAP.

 

[Big Ed]

My stock u-bolts were round. Can't tell for sure but yours look flat ... am I wrong?



You'll need a friendly A&P to do the log entry. It's a PMA part so minor mod. I did the work and my IA checked it out and signed off as part of my annual. Not really a whole lot to check other than proper torque and a taxi check for ground handling. Most of the work is getting it jacked up and getting the old single bolts out, which is a $%@#@. If you do that, buy a ball joint pickle fork and have a selection of pry bars.

 

[flyingskier]

They are flat, correct. '91 for what it's worth. I don't think they were ever replaced but I can double check the logs.