jbDC9
Well Known Member
Help! I've sent two emails on this question to Van's but the replies get tossed out by my spam filter... so I'll try it on y'all instead.
I have a flying -8 QB (140 hrs) and have noticed a series of cracks in a forward belly skin. My exhaust system is a 4 into 1 pipe... since I've not heard of cracks located here on other -8s, it's gotta be the exhaust causing these cracks. Reference Drawing #36, Forward Fuselage Sub Floor. The cracks are in the outer F-850PP skin where both F-836PP floor ribs attach; cracks are at the aft ends of the 836 ribs. Pics are attached; cracks are stop-drilled for now.
As far as a fix, I'm thinking of two external skin patches using some fairly thick (.032?) stock, roughly 2"x3", maybe a bit bigger, to bridge the "gap" at the aft ends of the 836 ribs and help transfer the vibration loads to the 850 skin. I can't get in there to buck solid rivets so I'd use flush 3/32 Cherry/pulled rivets instead. Would it help to smear some Pro Seal or JB Weld between the patches and skin to get a good grip and hold it all tight or would that not help at all?
So what'choo guys think? Does that sound reasonable or is there a better method to be used?
And just as an observation; sure glad I haven't painted it yet! I'd hate to mess up a nice paint job with cracks and patches...
I have a flying -8 QB (140 hrs) and have noticed a series of cracks in a forward belly skin. My exhaust system is a 4 into 1 pipe... since I've not heard of cracks located here on other -8s, it's gotta be the exhaust causing these cracks. Reference Drawing #36, Forward Fuselage Sub Floor. The cracks are in the outer F-850PP skin where both F-836PP floor ribs attach; cracks are at the aft ends of the 836 ribs. Pics are attached; cracks are stop-drilled for now.
As far as a fix, I'm thinking of two external skin patches using some fairly thick (.032?) stock, roughly 2"x3", maybe a bit bigger, to bridge the "gap" at the aft ends of the 836 ribs and help transfer the vibration loads to the 850 skin. I can't get in there to buck solid rivets so I'd use flush 3/32 Cherry/pulled rivets instead. Would it help to smear some Pro Seal or JB Weld between the patches and skin to get a good grip and hold it all tight or would that not help at all?
So what'choo guys think? Does that sound reasonable or is there a better method to be used?
And just as an observation; sure glad I haven't painted it yet! I'd hate to mess up a nice paint job with cracks and patches...
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