912 ULS Crankshaft Nut Torque Question

Hi guys,

I just wanted to follow up and let you know how everything came out. 

The gearbox work was due to a prop-strike on my Flyitalia MD3 Rider (registered as experimental) when the nose gear fork folded over during a crosswind landing.  I was down on the mains, had just applied right rudder to maintain center when the nose gear touched down and, apparently, that lateral load caused the fork to folder over.  The fork was aluminum and had very bad inner-granular corrosion and internal cracks which was not visible on the outside.  My A&P said it was just a matter of "when" it was going to fail, but I still felt bad about it.

Lockwood inspected my gearbox.  There was no damage from the prop strike but there was some wear of the gears so I had them replace the gears anyway.  I got a new Sensenich three blade prop and had a new nose gear fork fabricated from steel.

The crankshaft nut and gearbox reinstall went perfectly.  I studied and followed all the instruction from the manuals, made up a checklist of steps and had purchased the tools to do the job right.  It actually turned out easier than I had hoped and everything went exactly right the first time!  I really appreciate the advice from Rotax Wizard and Roger. 

The prob install was fairly easy too, although I did re-pitch twice to get to the correct ground RPM.  I now have 15 hours on the new setup (with a prop re-torque at 5 hours) and everything is looking very good.  The new prop seems to be worth about 20 extra horsepower.  Before a good climb rate was 1000fpm and now it will easily break 1200fpm. 😁

Thanks again for the help!

Glad it all worked out. Time to fly and have fun now.

I guess I will revive this question. Had Lockwood rebuild my gearbox (1,000 hr.) They told me to torque the crankshaft nut to148ft. Lbs. I asked about this change and they said the latest line manual said 147. What is the correct torque 220 or 147 ff. Lbs.? February 17 th,2025? Thanks

According to the Heavy Maint. manual of Sept. 2022 section 72-10-00 page 5 and figure 8.3 it is 300nm / 221 ft/lbs. Round off to 200 if you like. 

BUTTTTTTTT,

Line Maint. manual dated July 2021 section 05-50-00 page 12 says to torque to 200nm / 147 ft/lbs. People seemed to use 150 rounded off.

Both 912ULS and 912iS Heavy maint. say use 300nm / 221 ft/lbs

Thanks Roger