Engine mount lower bolt clearance issue

[runbjo]

After haveing lined up and drilled the jab 3300 std gear engine mount to the fuselage, I am left with limited clearance for the self locking nuts on the lower bolts on both sides. I have to cut back on the length of the lower bolt on both sides to not interfere with the landing gear tubes inside, and may have to look for a nut with less height. Anyone else had the same issue? any suggestions is highly appreciated.

Kind regards
Rune Bjørkelid
www.flyfabrikken.com

[peter anson]

Hi Rune, I had exactly the same problem. I managed to get enough clearance by cutting down the screw and filing the top of the nut on one side. I think I was able to retain the washer. If you haven't cut the countersink for the screw head yet I would advise not doing it. Grind some clearance in the fibre-glass cowl and use AN-4 bolts.

Peter,
Sonex 894

[Bryan Cotton]

Rune,
I had space for the nuts but not the excess thread. Picture and note down the page here:
viewtopic.php?f=39&t=578&start=380

[LarryEWaiex121]

Rune,
On condition inspection I ran across a similar situation on my Waiex. The bottom machine screw on the left gear leg was in place but I could turn the machine screw with some effort with a Phillips screwdriver. I had previously ground a small wrench to a very thin profile to get it on the nut next to the gear tube. No matter how hard I tried, I was unable to get the proper preload (torque) on the screw.
The unit will continue to work in shear but there was no tension on the screw.
Frustrated, I assessed that more might be better than less and drilled another hole just above the bottom hole and installed a 3rd screw that had access to the nut. So now I have 3 bolts in shear and two in tension. Properly torqued up.
Sometimes you can only fight something for so long and have to go a different direction. Right or wrong, this is how I addressed the matter.
Gook luck and hope you get your mount securely installed.

Larry
Waiex121YX, Camit 3300

[runbjo]

Hello again and thanks for sharing ideas and experiences. I ended up using the MS21042 self locking nut, since there were no room for the AN363. This is copied from Aircraft Spruce part description:

"The MS21042 all-metal stop nuts are designed for use in high temp installations (up to 450°F). MS21042 nuts are shorter than the AN363 nut but develop the same tensile strength"

So I figured this will do the same job as the original AN363 nut, but take up much less space. The picture is showing the r/h lower corner of the engine mount. Problem solved :D

Engine mount lower bolt