premature engine failure at 400 hrs

The Jabiru Engine which is used in many other aircraft.

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foxdog
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premature engine failure at 400 hrs

Unread post by foxdog » Tue Sep 18, 2018 4:27 pm

Hi Guys,
I was very disappointed with the premature engine failure of my Jabiru SP 120 on 01 07 2018 .
The engine was well cared for and operated correctly .
How i got away with my life and not scratching the aircraft is another story.
The failure was caused by an exhaust valve head breaking off and smashing a hole through the piston on No 3.
This was on a flight with everything in the green as it has always been.
Would you think this was just bad luck.
What precautions are there to stop this sort of failure.
Regards,
Foxdog
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Re: premature engine failure at 400 hrs

Unread post by V5 - LEO » Tue Sep 18, 2018 4:39 pm

....was it the Jabiru engine?
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Re: premature engine failure at 400 hrs

Unread post by Marius Schrenk » Tue Sep 18, 2018 6:01 pm

V5 - LEO wrote:
Tue Sep 18, 2018 4:39 pm
....was it the Jabiru engine?
How many lycoming/conti engines has had valve problems ??
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Re: premature engine failure at 400 hrs

Unread post by cage » Tue Sep 18, 2018 6:18 pm

foxdog wrote:
Tue Sep 18, 2018 4:27 pm
...
I was very disappointed with the premature engine failure of my Jabiru SP 120 on 01 07 2018 .
..
Isn't every engine failure premature?
Some may say that on a Jabi it is actually a feature ;)

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Re: premature engine failure at 400 hrs

Unread post by foxdog » Tue Sep 18, 2018 6:48 pm

Hi Cage,
Yes the 2.2 85 hp Jab motor
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Re: premature engine failure at 400 hrs

Unread post by foxdog » Tue Sep 18, 2018 6:53 pm

Hi Marius,
Can you answer your question is it many or not
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Re: premature engine failure at 400 hrs

Unread post by V5 - LEO » Tue Sep 18, 2018 8:04 pm

Marius Schrenk wrote:
Tue Sep 18, 2018 6:01 pm
V5 - LEO wrote:
Tue Sep 18, 2018 4:39 pm
....was it the Jabiru engine?
How many lycoming/conti engines has had valve problems ??


....lots, all engines are prone to a breakdown, it is mechanical after all - just seems that the Jab engines get more publicity on it :D
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Re: premature engine failure at 400 hrs

Unread post by Flooi » Wed Sep 19, 2018 6:06 am

Pity.... otherwise a great aircraft...
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Re: premature engine failure at 400 hrs

Unread post by Flooi » Fri Sep 28, 2018 9:01 pm

Foxdog. Any news? What was cause?
Pray tell......
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Re: premature engine failure at 400 hrs

Unread post by IWG » Mon Oct 01, 2018 10:30 am

Hi Foxdog,
Was the remaining valve stem bent or was it straight ?
This is an important indicator as to was the valve stuck open and hit by the piston,
or did the valve head drop and was then hit by the piston.

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Re: premature engine failure at 400 hrs

Unread post by Flooi » Tue Oct 02, 2018 6:39 am

IWG wrote: Hi Foxdog,
Was the remaining valve stem bent or was it straight ?
This is an important indicator as to was the valve stuck open and hit by the piston,
or did the valve head drop and was then hit by the piston.

IWG
Very inquisitive as well.......
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Re: premature engine failure at 400 hrs

Unread post by foxdog » Tue Oct 02, 2018 7:51 pm

Hi Flooi and IWG,
I will get back to you mid month,
Regards
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Re: premature engine failure at 400 hrs

Unread post by Shaunus » Wed Oct 03, 2018 7:44 am

Am also interested on your forced lob story, sounds like you did an excellent job!
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Re: premature engine failure at 400 hrs

Unread post by Flooi » Sat Oct 06, 2018 4:14 pm

I've been keeping an eye on Jabi issues for about ten years or so. My Jabi's have never
ever given an ounce of problems..... been cared for by Legair in Springs. I have noticed
some interesting stats though..... Avgas diet is better- especially if you fly little. Secondly,
engines that are run hard - 3000rpm cruise, seem to last longer. Lastly- If run too hot,
even for short periods- it WILL complain. It seems they need more TLC, but consider-
What can you buy for such competitive prices that can do so much? And I've got some
hours on plenty LSA....
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Re: premature engine failure at 400 hrs

Unread post by Chalkie » Mon Oct 08, 2018 8:05 am

Maybe some metallurgist can comment here...

As far as I know, all valves are made from two bits of metal, the valve stem and head are then friction welded together. IE the two parts forced together and spun to generate enough heat to melt the metal in the area of the joint. This will explain why occasionally an engine 'drops a valve.'

This could be for a number of reasons, such as a valve stuck open which the piston then hits. Or a failed valve spring allowing the collets and 'keeper' (Spring retainer) being dislodged, or the weld simply failing, etc.

Jabi use automotive parts, I wonder if the valves are made as described above, or not?
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