RV-4 lower cowl 'snubber' question

[rv7charlie]

The 'snubber' (best term I can think of) that keeps the cowl from being pushed up by air pressure has just broken on my -4. This is the 2nd time it's happened (2 different -4's) so I'm looking for a convenient, permanent fix. Anyone with photos to share of a reliable solution?

I've got an idea, but don't have any desire to re-invent the wheel.

This is the thing that typically mounts to the bottom of the starter or alternator & extends down & touches the inside of the bottom cowl.

Thanks,

Charlie

[Sid Lambert]

I've seen one mounted on the alternator bracket made from angle steel and covered with rubber. Sorry, I don't have a picture of it.

[szicree]

Is this something that I missed in the plans?

[rv7charlie]

Don't know if it's on the plans; I bought both already flying. However, both needed them since the 1st one started breaking hinge eyes & the current one's alternator fan sawed a hole in the cowl after losing the snubbers.

Charlie

Slobovia Outernational
Pocahontas MS

[Steve Sampson]

Charlie - are your cowls the early ones or the later (I think its called prepegged) ones? I dont have a snubber and dont think I need one.

I would be concerned that it would cause problems because the engine moves around and would stress the cowl and its hardware.

I worry for the air box a little for this reason. It allows some movement but is it enough?

[rv7charlie]

Both are older models, completed in '91 & '93. Both without doubt need the snubber. On the 1st plane, I noticed that the snubber was missing at an oil change but assumed it was unneeded since I didn't see any problems at that moment. Within about 5-10 hours of additional flight time, the spinner area hinges were destroyed & a couple of eyelets on both side hinges were broken off. The plane had seveal hundred hours on it prior to this, & no further issues after the snubber was replaced. There is an amazing amount of up-force on the front of the cowl at high speed.

I don't know if all RV's need them, but these two planes definitely do.

Charlie

[osxuser]

Cessnas use a little Lord cowl mount rubber riveted to a flange on the cowl, and that snubs up against a flat steel plate that is between the alternator and starter. They typically last about 1000 hrs.

[rv7charlie]

Ahhh, excellent thought. should be much easier to fabricate than the convoluted thing I fabbed out of 1 1/2" square tubing.

Thanks!

Charlie