RV-4 firewall buckle and cracks

I am building a -4 and have just heard about, and looked through the various archives, at all the messages about buckles in the firewall and various cracks around the W403 weldements. I have asked VANS if they ever made changes to solve this problem and am awaiting a response. I have seen Rob's suggestion that .040 sides solves the problem but am beyond that stage.

I would like to head the problem off before I have it. So, a couple of questions.

1) Have VANS designed the issue out in the later kits? Mine iss #4478.
2) What would you advise I do at this stage.

Thanks guys!

Steve.

Dont' panic

1.) Don't panic. The issue is real but is not the end of the world.

2.) Many Many RV4s are flying with the original configuration and have not experienced cracks.

3.) Van did do a redesign and you should hear from them with the details.

4.) If you can upgrade the parts conveniently do so.

5.) If not and you're planning to run a 200hp 360 in a very heavy airplane, then upgrade the parts no matter what.

5.) If you are planning a light 320 powered RV, then you may choose not to.

In the end, you will have to make the call. Let us know what you decide.


John

Firewall cracks, etc.

3.) Van did do a redesign and you should hear from them with the details. -John RV4

Ok, what were those 'redesign' features? Might you have some access which you could pass on?

Thanks,
Jim

try a search

Search here or the rv-list for detail. I don't have the dwgs here and don't remember the part no's off the top of my head. But this was discussed recently. Somebody just went through the update on a flying plane.

John

Thanks.
I'll do a search.

Firewall cracks

[Steve, I may be the guy who started all this. Last October we found a 1 1/2 inch crack in my firewall out of the upper left through bolt in the firewall and upon further evaluation ie. removal of the upper cover we found both weldment cracked completely through. Van's has stayed clear of this due to obvious potintial leagal issues but both Sport Aviation and Sport Aerobatics will have articles. My advice is if you have pre 1984 weldments throw them in the trash as that is wher they belong and install the post 1984 redesign. I only suggest this because the old weldment almost killed me. Roger Moore P.S. The aircraft was flown off 5000 ft concrete runways and was never overstessed

fuggedaboudit

Looking at your serial number, you must be late '90s vintage. The fix happened much earlier. I know of one RV4 that was "fixed" around 1990.
That airplane was beaten to a pulp on rough field by a pilot who must have been in the Navy .

You should be all set.

John RV-4 #3564

Mod Date

My RV-4, #1435 has modified lower weldments cf. original version. Is there a later mod to this??

I have an O-360 with wood prop (~960lbs), do aeros and fly off a grass strip. I am monitoring some small cracks on the lower engine mount bolt tubes adjacent the gear leg sockets after 250hrs and 300+ landings.

All info is good info.

Roger Moore said:

[Steve, I may be the guy who started all this. Last October we found a 1 1/2 inch crack in my firewall out of the upper left through bolt in the firewall and upon further evaluation ie. removal of the upper cover we found both weldment cracked completely through. Van's has stayed clear of this due to obvious potintial leagal issues but both Sport Aviation and Sport Aerobatics will have articles. My advice is if you have pre 1984 weldments throw them in the trash as that is wher they belong and install the post 1984 redesign. I only suggest this because the old weldment almost killed me. Roger Moore P.S. The aircraft was flown off 5000 ft concrete runways and was never overstessed

Click to expand...

Roger - no I dont think you are guilty! Over the last few days I have phoned around the UK and looked through the archives and YOUR problem appears almost unique as I understand things. As I understand it your problems were with the upper weldements. Yours is the only case I have noted.

The problem that concerns me is with the LOWER weldements. I was alerted by an article that appeared in the UK homebuilders magazine reproduced from the Ozzy version. It was written by an inspector who had observed the probem several times. My understanding is VANS made change in 87(?) and 94 but it still leaves an issue that sometimes shows up. The lower attach points cause the WD403 to flex and crack in the end with the symptom showing up as distortions in the firewall. The article also proposes a simple solution which requires tuppence halfpenny worth of additional welding to the mount.

The problem has not hit everyone but those operating off grass have experienced it quite a bit. This is much more common here than in the USA. Since in VANS mktng blurb they say "Others have used their RV-4s for sport of a different kind, flying regularly into backcountry strips for the fishing and recreation. More than one SuperCub pilot has been startled to land at a out of the way mountain strip and find an RV-4 already there. " it seems to me not an unreasonable thing to do.

I would welcome input from RV4 with post 94 engine mounts WD403 as to experience and fixes.

Thanks, Steve.

John - thanks for the support. You will see a longer reply to Roger Moore. Since I fly off grass - though pretty smooth - I would rather a little extra work now then when I have a problem. Trying to get my facts straight. Steve