Engine mounting bolt sheared

N8DAV8R said:

In the context of what started this thread, that seems like a great way to skip over a broken bolt and assume everything is good because the colors are lined up.

If you are checking that a bolt that has been in service and you can't see anything about the faster on the other side, the only way to know is to put a tool on it.

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Then why use torque seal inspection lacquer at all? This is an aviation standard practice....

Piper J3 said:

Then why use torque seal inspection lacquer at all? This is an aviation standard practice....

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Since it is a standard practice there would be reference documents that explain both why and more specifically how it should be used. You can review and apply those practices as you see fit, I'm not arguing that there is no use for it. The fact remains that it will tell you nothing about a fastener that is broken, elongated, or otherwise damaged threads. This happens to be the subject of this thread.

One very clear and good reason to use torque seal is to verify and document fastener tightening during assembly. There are good reasons to do this that are distinct from the of inspection of fasteners that have been in service.

The problem with checking the torque in a bolt secured with Loctite is that an under-torqued bolt will still likely show a high reading. When I built my 12 the instructions did not say to use Loctite but I and many others did anyway. Now the latest Rotax advice is to use it, so how do you then do a meaningful torque check?

I think the answer to RGMWA post # 53 is that you cannot do a meaningful torque check with a Loctite product used on the bolts in question here. An attempt to check the torque might result in the Loctite seal being broken requiring complete removal of the bolt, cleaning of the bolt and case, and then reinstallation with correct torque and Loctite 243.

That said, I believe that if the engine suspension bolts are installed at the MMH specification of 44 ft-lbs with Loctite 243 there is nothing in the Rotax MMH or MML that require rechecking the torque. The latest reference to checking the engine suspension that I have found is at 12-20-00, Page 4, February 01/2023 and it refers to the “Visual Inspection” of the engine suspension. There is no reference to checking torque. I respectfully disagree with rvbuilder2002's belief that the “Notice” in blue mandates a torque check, Rotax refers to it as a “General note”. To me it's a reminder to make sure we did the torque properly in the first place.