Repair question

[sixfivelrp]

Here is my dilemma, I had a small slip with the multitool trimming the canard cutout on the fuselage. My issue is if i do the standard repair of one inch per layer, i will end up grinding way out into the good stuff, as this is in the corner where the f22 reinforcement layup is.  See pics.  Second opinions are appreciated.

[Marc Zeitlin]

34 minutes ago, sixfivelrp said:

Here is my dilemma, I had a small slip with the multitool trimming the canard cutout on the fuselage. My issue is if i do the standard repair of one inch per layer, i will end up grinding way out into the good stuff, as this is in the corner where the f22 reinforcement layup is.  See pics.  Second opinions are appreciated.

While this cut seems to go through the inside layups, including the 4 BID reinforcement (given what the pic looks like), the area under the torque tube cutout is a low stress region. What _I_ would do here is to fill the cut with flox and then add 4 plies of BID in the same orientation as the reinforcement layups, feathering them in. The first ply would be 1" long, the next 2" long, etc.

And call it good.

And obviously, in the future, be really careful when grinding/cutting/drilling into major structural members.

[Anthony P]

What are your thoughts about carefully grinding and smoothing a 0.5" dia. or larger "stop crack" before the flox and reinforcement layups?

Not suggesting this, just wondering if this pre-layup geometry would make the repair worse, only a little better, or no change.

Thanks,

[Kent Ashton]

Stop-crack drilling doesn't work on fiberglass like it works on aluminum or plexiglass.  On fiberglass it just cuts more of the individual strands and makes things weaker.  Marc's fix will be fine.  After the surface is filled, you will likely not be able to detect any bump

[Marc Zeitlin]

11 hours ago, Kent Ashton said:

Stop-crack drilling doesn't work on fiberglass like it works on aluminum or plexiglass.  On fiberglass it just cuts more of the individual strands and makes things weaker.  Marc's fix will be fine.  After the surface is filled, you will likely not be able to detect any bump

And it's the inside, so it won't be filled or finished, so no one even cares what it looks like :-).

[sixfivelrp]

Thanks Marc, doesn’t get any easier than that.  On inside cosmetics, it still has to be good enough so one doesn’t stay up nights obsessing about it. Lol. Peel ply is my friend.