Cylinder Reassembly Question

by Danny Willis in 912 / 914 Technical Questions 6 years ago

Hi Guys,

I am having to replace the oil return tube and pushrod on one of my cylinders.
I followed the procedure in the HMM and have reassembled the cylinder to the engine.

Question 1: Do you have to prime the pushrod?
Question 2: Also is an oil purge necessary?
Question 3: I torqued the cylinders using the new torque method and when I went to the + 150 degrees and released the tension on the torque wrench, the nuts would unwind a small amount, like the stud was preloading, is this normal?

Thanks for your help,
Dan

Re: Cylinder Reassembly Question

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

The Hydraulic Valve Tappets will refill themselves as soon as the engine starts.
You may hear some chattering at first start. It should quiet up within 30 seconds.

If you have not opened the oil hose between the Oil Tank and the Oil Pump, a purge is not needed.
Hand Prop the engine before the first start until it registers some oil pressure.
If you have replaced the oil filter, this might require 50 or more turns.

The 912 heads are tightened in two stages.
They are first Pre-Loaded to 90 in-lbs.
And then "Torqued to Yield" by rotating them another 120°. (Not 150°)

Are you sure you have installed the Washers under the Flange Nuts?
Without the washers, you may be running out of thread and are twisting the stud instead of rotating the Nut.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: Cylinder Reassembly Question

by Danny Willis » 6 years ago

Danny Willis

4 5 2

Hi Bill,

Thank you for your response.

This is the new style case and requires the new torque method from the video on this site.

1st torque to 90 inlbs
2nd torque to 265 inlbs
Follow the pattern
Then one at a time loosen each nut 360 degrees
Then torque to 90 inlbs
Then an additional 150 degrees not 120

I confirmed this with Ronnie from South Mississippi Light Aircraft and he said the unloading was normal.

Thanks again!
Dan

Thank you said by: Wayne Fowler

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Re: Cylinder Reassembly Question

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 7.97k

Good to know!
It looks like the flat washers were also eliminated.
I hope they update the Heavy Maintenance Manuals soon as it is easy to miss the service instruction and video.

Ref:
The Service Instruction...
https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-025.pdf

The video...
https://www.rotax-owner.com/en/videos-topmenu/expanded-video-instructions/463-new-torque

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Capt. Siva,

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Cylinder Reassembly Question

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