UH-18SP Lift Duct - Page 3

The next thing we needed to do was to start making the inlet lip for the lift duct. We decided to make the rings for this before we cut the duct to the right highth because we werent sure where it needed to be cut because the plans said to cut the back of the cut even with the cockpit walls(no proble) and the front 2" below the wall(it was about 6" or 7" so we knew there was a mistake in the plans) We ended up cutting the back 1" below the walls and the front we just left where it was.

The first thing we did was cut 1 ring to fit around the duct. This first ring had to be cut into 4 pieces to get it on but This ring was the first ring in the front of the duct and the top ring on the back of the duct.

Here is a good pic on how that first ring works.

Here is a close up of the 2 rings that go on the back. We made the bottom one 3" wide and the top one 4" wide.

Then we added the next ring in the front.