Finishing the Trim Tab Preparation

Tue 10th Dec 2hr 30 min

Prepared the trim tab skin and spar edges. Deburred spar and skin. Countersunk the spar top flange and dimpled the bottom flange holes. Prepared and dimpled the horn pieces. Assembled HS-902 r & L with the HS-907 doubler and match-drilled them.

While I am thinking about getting a replacement trim tab skin, I went ahead and prepped this one, in case I decide to use it. This is not the easiest of jobs. It would have been better to prep the edges at the end of the skin before bending the tabs for instance. I tackled the leading edges initially with the spar clecoed in. This was okay for the lower edge but the spar was interfering with getting a good surface on the upper edge so I disassembled it and worked 'free-hand' with the small Scotchbrite wheel in the die grinder.

There is no more I can do on the trim tab for the moment so I began work on the recently arrived replacement parts. I started with the HS-902 L and R and the HS-907 front spar doubler. The trick here (and in any situation where you are preparing replacement parts) is to use the holes in the parts that have not been replaced as the 'master' holes for match-drilling the new part. If you drill from the new part into the old, you can get mismatched elongated holes. In this case, there was no problem on the right as both the spar and doubler were new but I was careful to drill from the aft side through the spar into the doubler on the left. This is the opposite direction to the original match-drilling.