Today's Message Index:
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1. 02:49 AM - Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts (Terminator)
2. 09:43 AM - Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts (rickpitcher)
3. 02:58 PM - Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts (jetboy)
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| Subject: | Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts |
Hi Chuck, I have flown a short time in a Jab 400 with a total time of 250hrs, here
in South Africa, with a good friend of mine. Three weeks ago we were in the
air at 2000ft ASL and fortunatly 5 miles from an arifield, when we heard a lowd
screech from the motor.
The noise stopped but we decided to land and inspect and gues what we saw ?!
Two sheared bolts!
I believe a Jab 80hp 2 seater had all 6 bolts sheer in Cape Town and now the preflight
procedure is to hold the fly wheel and turn the prop.
You will have noticed that washers have been placed on the bolts. This is simply
because the AMO was unable to tighten the bolts as they appeared to be too long,
although they are stock standard.
I will send this thread to the AMO, as you may have a good tip in your post.
Mark
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=101185#101185
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Message 2
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| Subject: | Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts |
Terminator wrote:
> Hi Chuck, I have flown a short time in a Jab 400 with a total time of 250hrs,
here in South Africa, with a good friend of mine. Three weeks ago we were in
the air at 2000ft ASL and fortunatly 5 miles from an arifield, when we heard a
lowd screech from the motor.
>
> The noise stopped but we decided to land and inspect and gues what we saw ?!
>
> Two sheared bolts!
>
> I believe a Jab 80hp 2 seater had all 6 bolts sheer in Cape Town and now the
preflight procedure is to hold the fly wheel and turn the prop.
>
> You will have noticed that washers have been placed on the bolts. This is simply
because the AMO was unable to tighten the bolts as they appeared to be too
long, although they are stock standard.
>
> I will send this thread to the AMO, as you may have a good tip in your post.
>
> Mark
Looking at the photo, I have a couple of questions/comments?:
1) I see that the 2 bolts are NOT sheared, but appear to have backed out. The 2
are opposite each other as if the mecahanic was torquing in the standard "star
pattern" where we torque opposite sides progressively to equally spread the
tension, and the 2 opposite bolts were inadvertantly missed?
2) The pic shows some red stuff on the washer that your AME added. Is that loctite?
Curious because the loctite 620 that is called for in the service bulletin
is green, not red.
3) I don't see any evidence of loctite in the threads that are showing, my bolts
had a residue of loctite along the shank that had to be cleaned off before replacing
the bolts with a fresh coat of Loctite 620.
4) The washers under the heads bother seem odd. The new bolts were not the same
length as the originals?
Curious.
Rick Pitcher
Jabiru 3300
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=101231#101231
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| Subject: | Re: Jab Service Bulletin JSB 012-1 Fly wheel bolts |
Hi,
Re the failed bolts it would be hepful to know if the SB had been done or if
they are original bolts at 250 hrs, and originally installed at the low torque,
for which the SB was issued to correct?
>From the photo I cannot tell if the bolts have sheared but this is likely as they
will shear at the crankshaft flange which is 1" in from the head.
Mention is made about washers. Standard fitting includes six belleville washers.
When I carried out the SB I hand threaded new bolts all the way without washers
to test for possible bottoming, and had no problems.
As for the colour of threadlock, only the SB and new engines use green 620, earlier
assembly would be red I expect - in my engine the old threadlock did not
have much colour and was only evident around the thread ends.
Seems like doing the SB or more will be less troublesome than replacing the alternator.
Regards, Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=101272#101272
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