The manual says you only have one chance to get the rear spar attachment holes right, so we decided to have some drill bushes made.
The base of the bush which is clamped to the rear spar is machined to 1 1/4" so its easy to ensure that the minimum edge distance of 5/8" is maintained to the top and bottom edges.
There are four drill bushes (M16 bolts) which are screwed into the base depending on the drill size being used.
