How much punishment?

Skyhook · #1 01-04-2005, 02:07 AM

My turf field goes from bumpy to *really* bumpy when the frost settles in and I have noticed that operating on that surface is what I imagine operating on cobblestones would be like.
Question: Just how likely am I to start seeing weldment cracks or other nightmare results from those gear getting beat so badly? I do recall the guy in UK who noticed engine mount welds cracking... Comments, anyone?

Vince Koehn · #2 01-04-2005, 07:30 AM

I know of a guy that replaced his engine mount because of multiple cracks after 2000 hrs. However some believe that was due to gear leg stiffners transfering too much of the shock to the engine mount. I fly off of a grass strip daily but fortunately it is really smooth.

VK

f1rocket · #3 01-06-2005, 07:38 AM

You're probably going to have engine mount cracks regardless. Of the 30 or so flying RV's around here, most have seen mount cracking right behind the lower, aft edge of the gear mount tube. I would check this area frequently. I'm not sure whether the stiffners make a difference or not since we have examples of both.

My own opinion is that it comes from trying to three point land these things. The rate of decent gets pretty high down around 65 kts and it's hard to three-point softly on a regular basis. That puts a lot of stress on the lower gear mount. I almost exclusively use a tail low wheel landing technique.

Skyhook · #4 01-06-2005, 08:57 AM

Thanks for the input, guys.
A couple of thoughts come to mind: 1) Gear stiffiners role.. I was thinking of installing those next warm spell, but, maybe not. 2) '..cracks regardless..' hmmmm. Maybe some premption move like reinforcing that weld point somehow would be reasonable?
If I get convinced operation from this field is causing or will cause the little red bird arthritis or worse, I will sell it and go back to the Citabria-type. I really don't want to do that yet.

f1rocket · #5 01-06-2005, 10:43 AM

I know the RV-7 mount (and I then assume the RV-9 mount as well) have gussets welded into the offending area. I don't know whether they fix the problem or not. I doubt it. I think it's a factor of the Whittman-syle gear legs flexing. In any event, it's not that big a deal to fix if it happens. Just loosen up the firewall bolts, slide the mount forward about 1/2 inch, and weld up the crack.

penguin · #6 01-06-2005, 11:46 AM

You're right that there have been several people in the UK who have cracked their engine mounts, but some of the strips there are really quite bumpy. There is mod that strengthens the gear mounts by welding gussets in the relevant area. I have posted your question on the "RV Squadron" yahoo group (English RVers news group) and invited you to join to read the replies!

Yours, Peter

Skyhook · #7 01-08-2005, 05:19 AM

Peter, that sounds like some input I need to access. Now, how would I get to that Yahoo group? Gotta plan that one out.

penguin · #8 01-11-2005, 06:56 AM

Skyhook,

Go to Yahoo groups and search for "RV Squadron", then apply to join, you will be approved in a day or so. There have been some replies to the question I posted - you need something called "the Netherthorpe Mod". However, newer RV-7 mounts may have the strengthening already installed.

Peter