ORIGINAL: Bax
ORIGINAL: fadi81
Hello All
My Sig 4* 40 manual says not to drill and tap the glass filled adjustable engine mount as this is going to weaken it.
But then how can I install my engine? What bollt shall I buy?
Please help, I've never assembled a plane before, and I am stuck at this phase
Thanks
Fadi
They said "drill and tap". It's tapping the hole for the screws that's the problem. They don't want you to use the mount, itself. to retain the screws. Drill for bolts and use nylon locknuts. Put a washer under the head of the bolt, and one between the nut and the mount. If you tapped the mount and properly-tightened the bolts, then you've also put a strain on the mount. This would also go for drilling slightly undersized and using sheet-metal screws. Another no-no. That effectively does the same thing as tapping the mount.
Of course everyone has their opinion, but if you read Dave Brown's tech sheet for thier mounts, they recommend using the sheet metal screws provided.
Tapping the nylon is not the same as using sheet metal screws (in my opinion).
[link=http://www.dbproducts.com/downloads/pdf/mm_tech_sheet.pdf]Dave Brown Engine Mounts Technical Data Sheet[/link]