Ernesto Sanchez wrote:

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

http://home.teleport.com/~guy_noir/images/rv/small_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
gNuOy_SnPoAiMr@teleport.com

Mark wrote:
I remember back in 1992 or so, a friend of our Squadron leaders landed in
Ohakea with his pristine RV-4, and the wheel shimmy was so severe the engine
cut. During troubleshooting they found his wheel halves poorly torqued and
with undersized bolts. His two lower firewall brackets were both cracked. He
contracted a couple of guys in our sheet metal shop to replace them, but
when the guys wanted to peel back the skin to inspect the top ones, he
"didn't think they would be damaged" (this was his opinion as an
accountant). Of course one of the two top ones was also severed.
The new design doesn't look much better to the eye, but you don't hear any
complaints, and Vans has a very solid rep.
Mark

Apparently the wheel pants can flutter at high speed. To fix it you add weight
the front of the wheel pant.

Paul Lamar

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