912 ULS Crankshaft Nut Torque Question
in 912 / 914 Technical Questions
11 months ago
Re: 912 ULS Crankshaft Nut Torque Question
by Stephen Ford » 2 days ago
Lockwood is still using the 147 inch Lbs. torque, but is checking with hi-up’s at Rotax? Can anyone explain to me the part about checking the radial runout of the crankshaft after tightening the nut? It says if it is off some ( more than 0.08) , then to reinstall the nut and measure again? How does installing the nut affect the crankshaft radical alinement? And the taking it off and reinstalling it change it? Thanks
Re: 912 ULS Crankshaft Nut Torque Question
by Rotax-Owner » 2 days ago
We are looking into the crankshaft hex nut torque value conflict between the LMM and HMM manuals to see if Rotax has provided any updates.
The alignment may shift slightly when tightening the hex nut on the crankshaft. If the radial runout exceeds acceptable levels after the initial tightening, loosening and retightening the nut can help realign the crankshaft. This is a standard procedure in precision engine assembly, where correct alignment is critical.
Re: 912 ULS Crankshaft Nut Torque Question
by Rotax-Owner » 2 days ago
UPDATE!
The July 2021 Line Maintenance Manual (LMM) incorrectly lists the torque value for the crankshaft hex nut on Rotax 912, 912 ULS/S, and 914 as 200 Nm (147 ft-lbs.)
The 2021 Heavy Maintenance Manual (HMM) lists the correct torque value as 300 Nm (221 ft-lbs.)
Recap:
- 300 Nm (221 ft-lbs.) - CORRECT!
- 200 Nm (147 ft-lbs.) - WRONG!
Rotax will release an updated Line Maintenance manual that will reflect the correct torque spec very soon.
Re: 912 ULS Crankshaft Nut Torque Question
by Todd Bailey » 2 days ago
Bummer. I torqued mine to 219 foot pounds. Hope that isn't going to cause any problems.
Re: 912 ULS Crankshaft Nut Torque Question
by Rotax-Owner » 2 days ago
Todd, we will look into this and get back to you ASAP!
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