Quote:
Originally Posted by Mark Burns
Due to the recent loss of a VAF'er I decided to inspect my empennage very carefully.
I found a crack in the right elevator spar at the outboard attach point.
This is how it looked upon inspection. Just a black line.
I wiped the black off the left side but you can still see the crack below.
And here it is after the dye penetrant test.
It's an RV7A serial number 72183 with 908 hours.
Everyone please check your elevators carefully before your next flight!
Mark
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Mark thank you for an excellent post.
My knee-jerk response comes from looking at the pictures:
1 - In the first picture the crack looks like it is radiating from the rivet hole. This could be from:
a> None or incomplete de-burring of the rivet hole.
b> Too small a rivet hole as the rivet is stressing the hole from the inside.
c> Too big a rivet hole.
2 - Second picture: The dye penatrent is showing up around the nut and looks like it is even under the nut. This could be because:
a> Loss of chromate conversion protection in the area.
b> Movement of the nut - YET! It is only on one side so I doubt that is the issue.
c> Something in the order of Hard Dirt under the nut causing a stress point.
AHA! I also notice your 'witness mark' and that is looking good - So not a loose nut.
2 - In the second picture:
Notice the crescent shape of the dye. this indicates:
a> Uneven stresses across an area. It could be as unusual as the grain of the aluminum.
b> What is behind that area?
c> Sure looks like a Double is required in this area - Maybe an inner and an outer.
Please keep all of us posted with your findings and pictures.
Thank you very much for taking the time and effort.
Barry
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