Today's Message Index:
----------------------
1. 06:45 AM - Re: Jabiru Flywheel Bolts [Early models] (mhubel)
2. 07:32 AM - Re: Jabiru Flywheel Bolts [Early models] (Stephen Smith)
3. 09:34 AM - Re: Jabiru Flywheel Bolts Important Notice (Joe Ronco)
4. 11:18 AM - Re: Re: Jabiru Flywheel Bolts [Early models] (Keith Pickford)
5. 11:21 AM - Re: Jabiru Flywheel Bolts Important Notice (Gilles Thesee)
6. 01:00 PM - Re: Re: Jabiru Flywheel Bolts [Early models] (Tony Graziano)
7. 01:12 PM - Re: Jabiru Flywheel Bolts Important Notice (Jim Ballenger)
8. 01:19 PM - Re: Jabiru Flywheel Bolts Important Notice (Iberplanes IGL)
9. 01:46 PM - Max prop diameter on Jab 3300 (Rob Turk)
10. 02:56 PM - Re: Jabiru Flywheel Bolts Important Notice (Keith Pickford)
11. 03:04 PM - Re: Jabiru Flywheel Bolts Important Notice (Peter Harris)
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| Subject: | Re: Jabiru Flywheel Bolts [Early models] |
Is this going to be the "official" word from Jabiru? If so, will Jabiru be supplying
the new bolt types and washers?
Given the use of loctite 620, replacing the bolts every 100 hours seems like a
possible problem in itself. Getting these bolts out is a bit scary as a lot of
heat must be applied to things. Is it being suggested that once the new bolt
types are used, 100 hour replacements would not be needed? Also at this torque
level is the use of Loctite 620 still required?
According to the manual, it sounds like removal of the timing gear for "inspection"
is a minor engine tear down requiring the removal of the engine from the
airframe. This does not sound like a practical 100 hour inspection, it effectively
kills the use of this engine type. Is there a way to do it without removing
the engine?
It would be good to post detailed pictures of "fretted" gears so those of us who
are maintaining only one engine will know what we are looking for.
Should the gear need to be replaced, it sounds like drilling for the 1/4 inch dowels
is effectively a major engine tear down to remove the crank. Am I missing
something?
100 hours is not a lot of time to put on an aircraft engine.
--------
Mark Hubelbank
N708HU
CH601XL
Jabiru 3300
Rotec TBI 40 carb
Sensenich ground adj prop.
28 hr TAF
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270935#270935
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| Subject: | Re: Jabiru Flywheel Bolts [Early models] |
What is meant by "early" engines? It would be helpful to have serial numbers.
I don't want to ignore a potential problem but also don't want to go messing with
critical bolts that seem to be working just fine.
Steve
--------
Steve Smith
N601WF
Zenair Zodiac XL
Jabiru 3300
600+ hours
Sensenich composite - ground adjustable
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270946#270946
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| Subject: | Jabiru Flywheel Bolts Important Notice |
FWIW attached is a copy of the draft report on the flywheel bolt
breakage by Anton Lawrence with pictures for those interested in seeing
what the problem looks like.
Hope this helps.
Joe R
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
Thruster87
Sent: Tuesday, November 03, 2009 9:09 PM
Subject: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
<alania@optusnet.com.au>
Contributed by Anton Lawrence
Over the last couple of years there has been an increasing awareness of
a problem with the flywheel retaining bolts in the Jabiru 2200 and 3300
engine.
The problem is simple enough to identify, the bolts are breaking and
have caused in-flight engine failure. The cause has been much harder to
identify and has been blamed on loose prop and prop extension bolts.
There can be no question that loose bolts in this area will transfer
harmonic vibrations down the crank and precipitate movement of the
flywheel parts.
-------------------------------------------------------------------------
-------
Examination of the timing gear on engines with broken bolts has
identified severe fretting of the gear against the end of the crank,
this cyclic movement is the reason the bolts are breaking. The retaining
bolts are 5/16th socket cap screws property class 12.9, although some of
these are threaded full length, which wouldn=C3=A2=82=AC=84=A2t
normally be considered best practice, all the bolts are fracturing on
the shear line.
12.9 bolts have an ultimate tensile strength of 1220 MPa and yield
strength of 1100 MPa, it is normal to tighten these to within 90% of
yield; this is to ensure proper clamp pressure of the parts.
This would cause the Jabiru bolts to elongate by about 5 thou and is the
mechanism by which clamp pressure is maintained.
A company in Hamilton, Asseco has analysed this joint and come up with a
torque figure of 41 Nm for these bolts with lubricated threads and
washer face. I have used the formula from MIL-HDBK-60 and come up with a
figure of 43 Nm using the same lubrication and 56 Nm with no
lubrication.
The Jabiru manual states a figure of 24 Nm for these bolts with out
lubrication, it is my belief that this where the problem partly lies.
(Jabiru apparently now recommend 32 Nm but this is still almost
=C3=82=C2=BD the maximum preload the bolts can take.)
Contributed by Anton Lawrence
The CAA is working on an AD for these engines which will most likely
require the bolts to be replaced every 100hrs. It is very important that
as part of the replacement procedure the timing gear is removed and
inspected, if there is any sign of fretting the part should be replaced
and equally important is that the bolts are replaced irrespective of
their appearance.
Jabiru are now fitting three 1/4 inch dowels into the end of the crank
in an attempt to prevent this fretting, any new gear will have holes for
these dowels pre drilled. The fitting of the dowels into the crank is a
very precise job and should not be attempted by anyone other than a
qualified fitter, engineer or toolmaker. Asseco is one company which has
already completed ten of these dowel fitting operations, I
don=C3=A2=82=AC=84=A2t want this article to appear to be advert
for one company or an other, so if you want their contact details you
can contact me directly and I will pass them on to you.
=C3=82=C2=A9 Jabiru
In conclusion, if you have an unmodified Jabiru engine of either type in
any aircraft type you should immediately have the flywheel bolts and
timing gear inspected, if all looks OK you should replace the bolts
(reminder, 12.9 bolts should never be reused) and tighten them to
between 41Nm to 43Nm using molybdenum grease as a lubricant in the
threads and under the head, don=C3=A2=82=AC=84=A2t get any grease
on the bearing surfaces. If you use Loctite 620 in the threads and
grease under the head you should tighten to 46Nm, Loctite 620 and no
grease tighten to 53Nm.
If you are going to tighten these bolts to the above figures it is vital
the bolt has a =C3=82=C2=BD=C3=A2=82=AC=C2=9Ddiameter minimum
hardened washer under the head, if not the bolt will embed into the
alloy parts and preload will be lost.
Check the prop bolts and prop extension bolts for correct tightening and
also check to ensure the extension is running true and the tracking is
within 3mm, on some aircraft these have been found to be well off
centre. If you have 10mm prop flange extension cap screws installed with
Loctite 620, you can take them to 89Nm to reach 90% of yield.
I have also checked the torque for the Crankshaft Prop Flange Cap Screws
as these have also been found slightly loose, Jabiru recommends 40Nm but
these bolts are capable of taking 83Nm.
If all these bolts are tightened correctly and all the parts are running
true it should be possible to eliminate the problem of broken bolts.
When tightening bolts you should tighten to halve the required amount
following the tightening sequence, leave for an hour (no longer if using
Loctite 620) to allow for local relaxation and then complete the
tightening in one movement so as not to get stuck with static friction
at a lower level, I have calculated the turn of the nut (5/16 cap screw)
from snug tight to 43Nm be only 48deg so take care.
=C3=82=C2=A9 Loctite
Some notes on Loctite :
Jabiru has apparently changed their recommendation of Loctite 262 to 620
for the above parts. 620 is not specified as a thread lock product but
Loctite assure me it is good for the job as it has a longer time before
cure and higher temperature capabilities, you can download all the data
sheets from http://www.loctite.co.nz.
Unfortunately you won=C3=A2=82=AC=84=A2t find the friction
coefficients or nut factors on these sheets, I have had to dig deeper to
get these directly from Loctite.
-------------------------------------------------------------------------
-------
Anton Lawrence, RAANZ Tech Officer
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270894#270894
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| Subject: | Re: Jabiru Flywheel Bolts [Early models] |
Hi All
-
This does not come from Jabiru - It was sent out to RAANZ members in New Ze
aland by their technical officer-over two years ago. Don't know why it ha
s resurfaced. Early models I guess refers to engines with 5/16 bolts withou
t the dowels. It is an opinion not a requirement. Check the Jabiru web site
for their recommendations. www.jabiru.net.au service bulletin JSB 012-1 -
The torque specs provided in the RAANZ bulletin are worth considering when
changing the bolts. (Been there - Done that)
-
Regards
Keith
--- On Thu, 5/11/09, Stephen Smith <sRoydSmith@hotmail.com> wrote:
From: Stephen Smith <sRoydSmith@hotmail.com>
Subject: JabiruEngine-List: Re: Jabiru Flywheel Bolts [Early models]
Received: Thursday, 5 November, 2009, 4:31 AM
l.com>
What is meant by "early" engines?- It would be helpful to have serial num
bers.
I don't want to ignore a potential problem but also don't want to go messin
g with critical bolts that seem to be working just fine.
Steve
--------
Steve Smith
N601WF
Zenair Zodiac XL
Jabiru 3300
600+ hours
Sensenich composite - ground adjustable
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270946#270946
le, List Admin.
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| Subject: | Re: Jabiru Flywheel Bolts Important Notice |
Joe Ronco a crit :
> FWIW attached is a copy of the draft report on the flywheel bolt breakage by
Anton Lawrence with pictures for those interested in seeing what the problem looks
like.
Anton's article can be found in HTML form at :
http://contrails.free.fr/engine_jab_flywheel_en.php
FWIW,
Best regards,
--
Gilles
http://contrails.free.fr
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| Subject: | Re: Jabiru Flywheel Bolts [Early models] |
If I recall correctly, the problem with the bolt failures on the NZ aircraft jabJabiru
engines was eventually attributed to "bad vibrations" caused by a prop
not approved by Jabiru Aus. Ibelieve I have a report somewhere in my archives
and the report should be available, maybe in the Jab archives. I incorporated
the Jab recommended retorqueing and loctiting about two years ago and have rechecked
the bolts on my last two annuals and will continue to do so with my s/n
engine (I think-do not have my log book available) #644.
Tony Graziano
Zodiac 601XL, Jab 3300; 541 hrs
Sent from my iPhone
On Nov 4, 2009, at 1:17 PM, Keith Pickford <kpickford@xtra.co.nz> wrote:
Hi All
This does not come from Jabiru - It was sent out to RAANZ members in New Zealand by their technical officer over two years ago. Don't know why it has resurfaced. Early models I guess refers to engines with 5/16 bolts without the dowels. It is an opinion not a requirement. Check the Jabiru web site for their recommendations. www.jabiru.net.au service bulletin JSB 012-1 - The torque specs provided in the RAANZ bulletin are worth considering when changing the bolts. (Been there - Done that)
Regards
Keith
--- On Thu, 5/11/09, Stephen Smith <sRoydSmith@hotmail.com> wrote:
From: Stephen Smith <sRoydSmith@hotmail.com>
Subject: JabiruEngine-List: Re: Jabiru Flywheel Bolts [Early models]
Received: Thursday, 5 November, 2009, 4:31 AM
What is meant by "early" engines? It would be helpful to have serial numbers.
I don't want to ignore a potential problem but also don't want to go messing with
critical bolts that seem to be working just fine.
Steve
--------
Steve Smith
N601WF
Zenair Zodiac XL
Jabiru 3300
600+ hours
Sensenich composite - ground adjustable
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270946#270946m/contribution" target=_blank>http://www.matronics.com/contributionh
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| Subject: | Re: Jabiru Flywheel Bolts Important Notice |
Joe
Thanks. Pictures are worth a thousands words.
Jim
----- Original Message -----
From: "Joe Ronco" <joe@halzel.com>
Sent: Wednesday, November 04, 2009 12:28 PM
Subject: RE: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
FWIW attached is a copy of the draft report on the flywheel bolt breakage by
Anton Lawrence with pictures for those interested in seeing what the problem
looks like.
Hope this helps.
Joe R
-----Original Message-----
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of
Thruster87
Sent: Tuesday, November 03, 2009 9:09 PM
Subject: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
<alania@optusnet.com.au>
Contributed by Anton Lawrence
Over the last couple of years there has been an increasing awareness of a
problem with the flywheel retaining bolts in the Jabiru 2200 and 3300
engine.
The problem is simple enough to identify, the bolts are breaking and have
caused in-flight engine failure. The cause has been much harder to identify
and has been blamed on loose prop and prop extension bolts.
There can be no question that loose bolts in this area will transfer
harmonic vibrations down the crank and precipitate movement of the flywheel
parts.
--------------------------------------------------------------------------------
Examination of the timing gear on engines with broken bolts has identified
severe fretting of the gear against the end of the crank, this cyclic
movement is the reason the bolts are breaking. The retaining bolts are
5/16th socket cap screws property class 12.9, although some of these are
threaded full length, which wouldnt normally be considered best practice,
all the bolts are fracturing on the shear line.
12.9 bolts have an ultimate tensile strength of 1220 MPa and yield strength
of 1100 MPa, it is normal to tighten these to within 90% of yield; this is
to ensure proper clamp pressure of the parts.
This would cause the Jabiru bolts to elongate by about 5 thou and is the
mechanism by which clamp pressure is maintained.
A company in Hamilton, Asseco has analysed this joint and come up with a
torque figure of 41 Nm for these bolts with lubricated threads and washer
face. I have used the formula from MIL-HDBK-60 and come up with a figure of
43 Nm using the same lubrication and 56 Nm with no lubrication.
The Jabiru manual states a figure of 24 Nm for these bolts with out
lubrication, it is my belief that this where the problem partly lies.
(Jabiru apparently now recommend 32 Nm but this is still almost the
maximum preload the bolts can take.)
Contributed by Anton Lawrence
The CAA is working on an AD for these engines which will most likely require
the bolts to be replaced every 100hrs. It is very important that as part of
the replacement procedure the timing gear is removed and inspected, if there
is any sign of fretting the part should be replaced and equally important is
that the bolts are replaced irrespective of their appearance.
Jabiru are now fitting three 1/4 inch dowels into the end of the crank in an
attempt to prevent this fretting, any new gear will have holes for these
dowels pre drilled. The fitting of the dowels into the crank is a very
precise job and should not be attempted by anyone other than a qualified
fitter, engineer or toolmaker. Asseco is one company which has already
completed ten of these dowel fitting operations, I dont want this article
to appear to be advert for one company or an other, so if you want their
contact details you can contact me directly and I will pass them on to you.
Jabiru
In conclusion, if you have an unmodified Jabiru engine of either type in any
aircraft type you should immediately have the flywheel bolts and timing gear
inspected, if all looks OK you should replace the bolts (reminder, 12.9
bolts should never be reused) and tighten them to between 41Nm to 43Nm using
molybdenum grease as a lubricant in the threads and under the head, dont
get any grease on the bearing surfaces. If you use Loctite 620 in the
threads and grease under the head you should tighten to 46Nm, Loctite 620
and no grease tighten to 53Nm.
If you are going to tighten these bolts to the above figures it is vital the
bolt has a diameter minimum hardened washer under the head, if not the
bolt will embed into the alloy parts and preload will be lost.
Check the prop bolts and prop extension bolts for correct tightening and
also check to ensure the extension is running true and the tracking is
within 3mm, on some aircraft these have been found to be well off centre. If
you have 10mm prop flange extension cap screws installed with Loctite 620,
you can take them to 89Nm to reach 90% of yield.
I have also checked the torque for the Crankshaft Prop Flange Cap Screws as
these have also been found slightly loose, Jabiru recommends 40Nm but these
bolts are capable of taking 83Nm.
If all these bolts are tightened correctly and all the parts are running
true it should be possible to eliminate the problem of broken bolts.
When tightening bolts you should tighten to halve the required amount
following the tightening sequence, leave for an hour (no longer if using
Loctite 620) to allow for local relaxation and then complete the tightening
in one movement so as not to get stuck with static friction at a lower
level, I have calculated the turn of the nut (5/16 cap screw) from snug
tight to 43Nm be only 48deg so take care.
Loctite
Some notes on Loctite :
Jabiru has apparently changed their recommendation of Loctite 262 to 620 for
the above parts. 620 is not specified as a thread lock product but Loctite
assure me it is good for the job as it has a longer time before cure and
higher temperature capabilities, you can download all the data sheets from
http://www.loctite.co.nz.
Unfortunately you wont find the friction coefficients or nut factors on
these sheets, I have had to dig deeper to get these directly from Loctite.
--------------------------------------------------------------------------------
Anton Lawrence, RAANZ Tech Officer
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=270894#270894
Message 8
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| Subject: | Re: Jabiru Flywheel Bolts Important Notice |
Hello guys,
How can we be sure If all this problems were caused by using an improper
propeller? so we can rule that out. I=B4m planning to use a DUC Swirl
propeller. I know a few guys that have used them with great success.
Bye !
Alberto Martin
www.iberplanes.es
Igualada - Barcelona - Spain
----------------------------------------------
Zodiac 601 XL Builder
Serial: 6-7011
Tail Kit: Finished
Wings: Not Started
Fuselage: Started
Engine: Jabiru 3300
Message 9
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| Subject: | Max prop diameter on Jab 3300 |
The Jabiru 3300 installation manual lists the max prop diameter as 70".
Does anyone actually use that diameter or something close to it? If so,
on what plane and what are your experiences?
Rob
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| Subject: | Re: Jabiru Flywheel Bolts Important Notice |
Other thoughts were loose prop bolts and 4 inch prop extensions or prop ext
ensions not true
--- On Thu, 5/11/09, Iberplanes IGL <iberplanes@gmail.com> wrote:
From: Iberplanes IGL <iberplanes@gmail.com>
Subject: Re: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
Received: Thursday, 5 November, 2009, 10:19 AM
Hello guys,
How can we be sure If all this problems were caused by using an improper pr
opeller? so we can rule that out. I=B4m planning to use a DUC Swirl propell
er. I know a few guys that have used them with great success.
Bye !
Alberto Martin
www.iberplanes.es
Igualada - Barcelona - Spain
----------------------------------------------
Zodiac 601 XL Builder
Serial: 6-7011
Tail Kit: Finished
Wings: Not Started
Fuselage: Started
Engine: Jabiru 3300
Message 11
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| Subject: | Jabiru Flywheel Bolts Important Notice |
I found my engine shaking at various times (sometimes scary) depending
on
the power setting and I think it is caused by imbalance when mixture is
distributed unevenly L to R because of the lack of a regular symmetrical
induction plenum. It is also well worth getting the prop dynamic
balanced.
Although my prop was carefully static balanced it required 3 g weight to
get
a dynamic balance and now the prop is a long way from static balance. It
seems to mean that we had to compensate for imbalance in the engine
itself.
Peter
_____
From: owner-jabiruengine-list-server@matronics.com
[mailto:owner-jabiruengine-list-server@matronics.com] On Behalf Of Keith
Pickford
Sent: Thursday, 5 November 2009 8:26 AM
Subject: Re: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
Other thoughts were loose prop bolts and 4 inch prop extensions or prop
extensions not true
--- On Thu, 5/11/09, Iberplanes IGL <iberplanes@gmail.com> wrote:
From: Iberplanes IGL <iberplanes@gmail.com>
Subject: Re: JabiruEngine-List: Jabiru Flywheel Bolts Important Notice
Received: Thursday, 5 November, 2009, 10:19 AM
Hello guys,
How can we be sure If all this problems were caused by using an improper
propeller? so we can rule that out... I=B4m planning to use a DUC Swirl
propeller. I know a few guys that have used them with great success.
Bye !
Alberto Martin
www.iberplanes.es <http://www.iberplanes.es/>
Igualada - Barcelona - Spain
----------------------------------------------
Zodiac 601 XL Builder
Serial: 6-7011
Tail Kit: Finished
Wings: Not Started
Fuselage: Started
Engine: Jabiru 3300
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11/03/09
19:38:00
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