[jcadwell]

I'm considering the purchase of an older RV-4 that hasn't flown in a few years, for the right price.

One of the items that the seller mentioned is that the engine mount brackets are of the older/weaker type. He has purchased the newer brackets.

How hard is it to replace those brackets? Is it a bolt-in part, or do you have to disassemble part of the structure that requires aluminum work? I'm not a builder, and am not trying to become one if this is a major rework.

Thanks.

 

[gasman]

You would definitely want to talk to someone that has done this.

 

[WAM120RV]

Big Job.

My advice would be to inspect the lower half of the firewall, the engine mount and these weldments to see if there is any sign of cracking. If its all Ok leave it but have it as a regular inspection point.

If there is deformity or cracking then its a big job as these carry the load from the engine onto the longeron. The weight of the engine needs to be supported, bottom mount through bolt taken out, then the rivets that hold the weldment on need drilling out. Thats not an easy task as they are relatively long rivets and you need to make sure you follow their centre and not enlarge the hole.

This will mean you drill through the paint on the outside of the fuselage skin, so retouching in of the paint will be required. If the holes become oversize you may have to replace with larger rivets.

If you do this job or get it done it is worthwhile putting the extra gusset in as well which is shown in my blog.

Bottom line....... is this is something you need to factor into the negotiations. Its something someone who is skilled could do in a couple of days, but its also something that the unskilled could cause themselves a lot of pain on.

Fitting the gussets to an already built aeroplane requires a lot of crawling about upside down in that footwell.

I would not walk away from a good buy because of this, especially if there is no sign of a problem on inspection........ but even if there is not it needs to be factored in as it is work you may have to get done in the future. I wold guess that as the owner has bought the new weldments that there may be some cracking so get this checked carefully.