Ultralight crashes at Gawler 16/05/07

[Geoff]

To Dam Right Ian, I know of a mate that had a small oil leak in this area and has just tighten these bolts.

 

 

[Captain]

Based on this thread (bit of a freudian there) we have 1 reported problem from this cause in Gawler, but no other J owners are rushing forward to report similar incidents .... or are there?

 

I still have trouble grasping 5 mm stretching of these bolts as I suspect that they would fail before that.

 

So it could be a faulty manufacture, or crook material, or over torqued at some time in its life, or 5 mm longer originally or some combination.

 

Grant. We need a photo of the area of the failure on the stud. Can you post a closeup of the failed stud please?

 

Grant, please also advise whether that engine had ever been apart or any studs or other items replaced.

 

Given that I have spoken with numerous J owners who have done many hours more than 450 on their engines without issue, it seems to me that more careful consideration is needed before labelling this anything more than an isolated incident.

 

Now, can anyone list any other specific examples of this problem where we can collectively ferret out more details?

 

I'll also post this in a new thread in the J owners area in case this Clubroom location is missing someone.

 

Regards Geoff

 

 

[Captain]

Thanks for your input Donk.

 

Do you know what "maintenance" was supposedly over-done or not done to contribute to such a failure?

 

And did it just "fail" there or stretch as well?

 

 

[Guest brentc]

The engine that Donkey speaks of had been the subject of a recent rebuild where the stud bolts were torqued to the factory specs at the time which in the end appeared to be incorrect when it snapped off. It also snapped off at the base of the nut when being fitted and torque settings of less than those specfied were applied.

 

 

[Yenn]

We have to be aware of the correct method of torquing up studs. It can vary from location to location. What was the requirement for lubricating the bolt? Was the torque wrench calibrated?

 

I am not aware of any requirement to torque up barrel bolts, only to check all nuts as part of ongoing maintenance, and those barrel bolts can be difficult to get at, in my experience.

 

 

[Guest Teenie2]

True Ian, I'm thinking the same thing. They are to be replaced at 1,000 for the top end as a precautionary, so I'm surprised they could stretch 5mm. 5mm stretch from a solid stainless steel bolt to me defies the laws of physics and metalurgy. If you've seen them they appear to be around 1.5cm across and very heavy. I just removed my studs after 440 hours and they are within original spec on my 6 cylinder.

Stainless steel bolts are you sure ? I very much doubt it.