hohoho...
after more ivestigating,here's what i find..

here...http://microlighters.co.za/viewtopic...6fb17ec0137cbc


912S and late model 912 80 hp 75 mm flange pattern for Ultrailght model propeller bolt holes are not threaded

so we use the stronger AN5 BOLTS,


so my flange are not thread (early model)
maybe AN5 is my option...
what do you think gentleman

Jf