On Tuesday, February 3, 2015 at 3:45:05 PM UTC-5, Don Johnstone wrote:
I am well aware that in the past such modifications were made to simple
wood and fabric constructed gliders, cutting and patching a hole in fabric
or indeed metal skins is a completely different matter to drilling holes in
a GRP structure, the best that can be said is that such action has not
failed, YET, or maybe not.

Um, as one who owned one of these brutes, until it perished
in the great Barstow fire, I also made a hole to lubricate
the drive knuckles. OMG! Great Balls of Fire! The World will END!
Well no, the 3/32" hole is thru the fabric seal,
NOT through GRP structure. The track/follower assembly is
accessed via a factory-provided inspection plate.

Really now...