Here's a picture of the steel longeron fitting that cracked on a
friend's RV-4:

http://home.teleport.com/~guy_noir/i...ll_fitting.JPG
(The photo is an RV-3, which is similar).

I don't remember where it cracked, but the two ears connected to the
longeron were completely separated from the forward gusset, leaving the
lower corner engine mount attachments pretty much unconstrained. Not to
worry, though, he believes that they broke within the first 20 hours of
flight, operating from a fairly rough strip (Dietz Airpark in Canby,
OR). He managed to log hundreds of hours over many years before he saw
that his engine mount was cracked during an oil change, and he decided
he needed to do something about it.

His first indication that he had a problem ("...from day one", he said,
"From day one?" I asked, "Really?" "Yes", he said) was that his
landing gear was sagging, which he could see from the gap forming at the
front of the landing gear fairing, and the compression at the back side.
He also noticed a popping noise during taxiing, which he initially
thought was oil canning, but now believes were the broken edges of the
fitting rubbing together. He thinks it's likely that many RV-4's flying
around now have the same problem.

He told me that Van's was aware of the problem, and had re-designed the
lower fittings, but they never told him about it. He showed me the
re-designed fitting. It still looks pretty flimsy, the main difference
is that the two ears which bolt and rivet to the longeron have been
combined into one bent up angle.

So, RV-4 (and RV-3) owners, have you inspected the nether regions of
your firewall recently? Is this problem well known in the RV community?
Does it apply to -6 and later models? Has anyone gotten a service
bulletin from Van's on this matter?

Thanks,
--
John Kimmel


I think it will be quiet around here now. So long.