Today's Message Index:
----------------------
1. 04:22 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (hooverra)
2. 06:02 AM - Small Connector for Ray Allen Trim Servo Cables? (Dennis Johnson)
3. 07:19 AM - Small Connector for Ray Allen Trim Servo Cables? (Owen Baker)
4. 07:31 AM - Re: Small Connector for Ray Allen Trim Servo Cables? (user9253)
5. 09:05 AM - Re: Re: Small Connector for Ray Allen Trim Servo Cables? (Robert L. Nuckolls, III)
6. 09:44 AM - Electrical architecture with aux battery (user9253)
7. 09:46 AM - Re: Teaching vs. Propagandizing (Robert L. Nuckolls, III)
8. 10:25 AM - Re: Teaching vs. Propagandizing (Robert Borger)
9. 12:27 PM - Re: Re: Small Connector for Ray Allen Trim Servo Cables? (Robert L. Nuckolls, III)
10. 12:27 PM - Re: Teaching vs. Propagandizing (Robert L. Nuckolls, III)
11. 12:49 PM - Re: Electrical architecture with aux battery (Robert L. Nuckolls, III)
12. 12:49 PM - Re: Essential Bus question (Eric M. Jones)
13. 01:04 PM - Re: Teaching vs. Propagandizing (Tim Andres)
14. 02:17 PM - Re: Electrical architecture with aux battery (user9253)
15. 02:44 PM - Re: Electrical architecture with aux battery (user9253)
16. 04:30 PM - Re: Teaching vs. Propagandizing (Robert L. Nuckolls, III)
17. 04:31 PM - Re: Re: Electrical architecture with aux battery (Robert L. Nuckolls, III)
18. 04:33 PM - Re: Re: Electrical architecture with aux battery (Robert L. Nuckolls, III)
19. 04:35 PM - Some data points and pictures from my Rotax 91X School (Robert Borger)
20. 06:43 PM - Rotax crank failures (Robert L. Nuckolls, III)
21. 07:20 PM - Change of business model . . . (Robert L. Nuckolls, III)
22. 07:26 PM - Re: Rotax crank failures (Tim Andres)
Message 1
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| Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
http://www.digikey.com/catalog/en/partgroup/en3-series/2186
switchcraft en series is sealed, small and works well for trim cables. It takes
reasonable soldering skill but not bad.
Ralph
--------
Ralph & Laura Hoover
RV7A N527LR
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418113#418113
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| Subject: | Small Connector for Ray Allen Trim Servo Cables? |
Hi Valin,
I used mini S-VHS connectors for my Ray Allen trim servos. That is what
the company recommends and S-VHS connectors are round and have the
benefit of passing through existing round holes, unlike D-Sub
connectors. Mini S-VHS connectors from DigiKey are available with
different numbers of wire connections, depending on which servo you're
connecting them to. I don't see any need for environmentally sealed
connectors in my Legacy.
If I had it to do again, I'd go with Ron's suggestion of soldering the
wires together, with a generous service loop. Since you're flying
before final painting, that might be emotionally difficult because
you'll have to cut the wires to remove the rudder and elevator when you
paint, but it's not that big of a deal. I think soldering the wires
together for first flight, cutting them apart for painting, and then
soldering them back together is going to be less trouble and more
reliable than finding and using connectors.
If I absolutely had to have connectors instead of soldering the wires
together, I'd use Bob's method of D-Sub connectors without the shell,
covered by heat shrink. You might have to slightly enlarge some of the
pass through holes to get the connector through, but that's not a
problem.
I also recommend buying the wire from Ray Allen to connect to the
servos. I know it's tiny 28 gauge, but it comes in a very durable
sheath and will be much neater than making your own bundle from manually
twisting 22 gauge wires together.
Best,
Dennis
Lancair Legacy, 680 hours
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| Subject: | Small Connector for Ray Allen Trim Servo Cables? |
2/5/2014
Hello Valin, Why not purchase several male and female machined D sub
pins? Here is just one example:
http://www.newark.com/cinch/030-1952-000/d-sub-contact-pin-24-20awg-crimp
/dp/12M3924?mckv=sShye0Dzw|pcrid|33869844621|plid|&CMP=KNC-GPLA
(You may prefer the high density version.)
Then you just crimp the appropriate gender pin on each of the 10 Ray
Allen bare wire ends and stick the pins together. Some tips and
comments:
a) Be sure to put the appropriate sized heat shrink over the wires
before crimping the pins onto the wires so that you can slide the heat
shrink over the joined pins before heat shrinking. The heat shrink will
help keep the pins together when joined and provide some environmental
protection.
b) If you desire additional environmental protection some goop can be
applied to the ends of the heat shrink.
http://eclecticproducts.com/e6000_retail.htm
c) If you are not satisfied with how firmly the pins connect together
put a very slight bend in the male pin before inserting it into the
female pin to assure a better connection.
d) You can stagger the ends of the cut wires so that all of the pins do
not remain in one large clump when the job is finished.
e) These connections can be separated (for later reconnection) by
carefully using a razor blade or Xacto knife to split the heat shrink.
OC
=============
Time: 10:38:59 AM PST US
Subject: AeroElectric-List: Small Connector for Ray Allen Trim Servo
Cables?
From: "Valin" <thorn@starflight.aero>
Hello,
Can anyone recommend a good, small, preferably environmentally sealed
connector
to use on the five conductor cable of 22 AWG wires that run to each of
the Ray
Allen trim servos? If I werent going to be flying in primer first Id
probably
just splice the wires together for the entire run. But with paint and
control
surface removal in the known future Id like to make removal of the
control
surfaces easier with connectors on these cables. They need to be low
volume
connectors to fit in the space where theyll be.
Thanks,
Valin Thorn
Lancair Legacy Project
Boulder, Colorado
Message 4
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| Subject: | Re: Small Connector for Ray Allen Trim Servo Cables? |
I think this was Bob's idea but I could not find it on his website. Use 5 sets
of male-female D-Sub pins without any shell at all. Cover each mated pair with
heat-shrink. If the joints have to be weather proof, use adhesive lined heat-shrink.
The heat shrink will have to be cut to separate the connections, not
a big deal.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418118#418118
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| Subject: | Re: Small Connector for Ray Allen Trim Servo |
Cables?
At 06:21 AM 2/5/2014, you wrote:
>
>http://www.digikey.com/catalog/en/partgroup/en3-series/2186
>
>switchcraft en series is sealed, small and works well for trim
>cables. It takes reasonable soldering skill but not bad.
Interesting find! Thank you. According to the
data sheet
http://tinyurl.com/le3gwtp
these are available in 20AWG crimp pins. There's
a 95% chance that the el-cheepo (and platinum
plated) 4-quadrant tools will install these
pins. Unfortunately, Digikey doesn't stock the
crimp versions yet but they will do special orders
of 10 or more connectors. I'll put these on
my list of "things to go buy and evaluate" and
may add them to the AeroElectric Catalog. But
if they're popular, Digikey will eventually
stock them.
Switchcraft is a staid, old-line supplier of
electronic components . . . low risk.
Bob . . .
Message 6
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| Subject: | Electrical architecture with aux battery |
Attached is a circuit with a brownout battery (non cranking). It will be kept
charged through a diode when the E-Bus alternate feed is off. The aux battery
will be connected in parallel with the main battery when both aux battery switch
and the E-Bus switch are turned on (expected normal operation after engine
start). This circuit is not for my plane. I offer it for discussion and comments.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418123#418123
Attachments:
http://forums.matronics.com//files/z_11_modified_2_971.pdf
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| Subject: | Re: Teaching vs. Propagandizing |
At 05:01 PM 2/4/2014, you wrote:
Gents,
This thread should probably be on the Rotax list,
but sometimes we take what we can get where we can get it.
I will suggest this is an appropriate discussion
for the purpose of honing our critical analysis
tools. Most of the 'tiger teams' on which I served
at Beech were not wrestling with electrons . . .
but they were grounded in the same physics that drives
everything made up of matter and driven by energy.
I too have attended Lockwood=92s 91X class and have
seen the engine and heard the story from
Dean. There was also a second story related
which involved loss of oil due to vibrational
damage to an extended fitting to mount the oil
pressure sensor. A fitting was inserted between
the oil pressure sender and the engine case. The
fitting was put in place to add a pressure switch
to illuminate a light should the oil pressure
drop below the switch pressure set point. Now
you have a classic mass on a spring with the
sender hanging out on that extension. I don=92t
remember how long that arrangement held up but I
don=92t believe it was very long before the
extension piece broke, the gentleman=92s low oil
pressure lamp illuminated and the contents of the
oil sump were dumped overboard. Again, the
report was that the engine probably didn=92t run
longer than 10-20 second before it seized once
the oil was gone. I can=92t speak to the accuracy
of the 10-20 seconds without oil before seizure
not having been there in either case. But the
takeaway point was that the Rotax 91X engine
requires continuous lubrication and that any
interruption in that lubrication would be detrimental to your engine.
Great example!
BTW, I have moved my oil pressure sender off the
engine and onto the firewall using a length of SS
braided pressure line. Saves vibrational
stresses on the sender and the fitting to the engine.
There you go . . . this is a demonstrable example
of fitting all the puzzle pieces together. I'm
betting that the fittings which broke were brass . . .
a non-ferrous material of which all such materials
have a service life.
There's a feature in the study of strengths of
materials called the S/N to Failure. Stress
levels/Number of cycles to failure curve for
steel becomes flat at some value of S/N
below N of 10M. The rule of thumb for testing
steel parts is, "If you can't break it in
10,000,000 cycles, you aren't going to break it."
On the other hand, non-steel parts have a service
life at ANY stress level. It's just parts like
wings, struts and tail feathers are so lightly
stressed that their service lives far exceed the
expected life of an airplane. But poor attention
to details of design, operation and maintenance
have proven spectacularly catastrophic.
[]
It's that sneaky old s/n ratio thingy that makes
us attentive to adding wire support immediately
adjacent to a crimped or soldered bundle of wire
strands.
Having a rudimentary understanding of s/n ratio
is useful for stringing wires, installing rivets,
building support brackets . . . and yes . . .
evaluating cause-effect for connecting rods coming
through the crankcase. It'a all the same physics.
One of the many things I like about my Grand
Rapids EIS 4000 is that it stays up during engine
start and the default page shows oil pressure so
I know immediately upon engine start if there=92s oil pressure.
Just my 2=A2 and worth at least half that.
Undoubtedly . . .
Blue skies & tailwinds,
Bob Borger
Bob . . .
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| Subject: | Re: Teaching vs. Propagandizing |
On Feb 5, 2014, at 11:46 AM, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
At 05:01 PM 2/4/2014, you wrote:
Gents,
There you go . . . this is a demonstrable example
of fitting all the puzzle pieces together. I'm
betting that the fittings which broke were brass . . .
a non-ferrous material of which all such materials
have a service life.
Robert, If I remember correctly, the fitting was brass. Broke off just about flush
with the oil pump housing. Which is right where the maximum vibrational
stress would have been applied.
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop (50 hrs).
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger@mac.com
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| Subject: | Re: Small Connector for Ray Allen Trim Servo |
Cables?
At 09:30 AM 2/5/2014, you wrote:
>
>I think this was Bob's idea but I could not find it on his
>website. Use 5 sets of male-female D-Sub pins without any shell at
>all. Cover each mated pair with heat-shrink. If the joints have to
>be weather proof, use adhesive lined heat-shrink. The heat shrink
>will have to be cut to separate the connections, not a big deal.
Last panel on this comic book . . .
http://tinyurl.com/c5v2xvm
Bob . . .
Message 10
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| Subject: | Re: Teaching vs. Propagandizing |
>Robert, If I remember correctly, the fitting was brass. Broke off
>just about flush with the oil pump housing. Which is right where
>the maximum vibrational stress would have been applied.
Bingo . . .
Bob . . .
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| Subject: | Re: Electrical architecture with aux battery |
At 11:43 AM 2/5/2014, you wrote:
>
>Attached is a circuit with a brownout battery (non cranking). It
>will be kept charged through a diode when the E-Bus alternate feed
>is off. The aux battery will be connected in parallel with the main
>battery when both aux battery switch and the E-Bus switch are turned
>on (expected normal operation after engine start). This circuit is
>not for my plane. I offer it for discussion and comments.
There is a way to avoid charging the aux
battery through a diode and eliminate one
switch.
http://tinyurl.com/7ro5yuc
Bob . . .
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| Subject: | Re: Essential Bus question |
> You also have to take into account that unlike the LyCo's, the Rotax has a five
piece crank that is pressed together with nothing but the pressure of the
fit to keep it together and aligned. I would imagine the trail of tears would
include a piston seizure that causes the crank to come out of alignment which
not only destroys a bearing or two, but gives the various crank sections a chance
to beat upon each other. The reason for the multipiece crank is so that it
can be made shorter by reducing the clearance between the side of the rod, see
picture. With so little clearance between the rod and the adjacent crank web
the twisted, misaligned crank now has a chance to really start beating on the
rods, the piston skirts, and any pieces that have come loose. Of course the Rotax
engineers have reduced clearances between the rotating assembly and the case
halves to shave off more weight and by now the bearings are not only being
twisted out of their seats but the case webs are being hammered, too.
> I find this scenerio to be highly unlikely! If this were the case, then
I would wager that there would be cases of this type of failure during
> normal operation, due to the stress and vibration created during high power running.
Roger
Let me venture way outside my pay-grade and offer an opinion that the Rotax multipiece
crank is in no way an inferior design, and in fact offers lots of advantages:
1) Cost
2) The connecting rods need no end bearing caps, thus they are stronger and lighter.
3) Exceptional resistance to failure from torsional vibration.
4) The ability to use different metals for the various parts.
5) Shorter crank.
6) The ability to use roller bearings. (I have no idea if they actually should
or do).
As long as the rod and main bearings are good, the idea that the crank can come
apart is simply a distraction. Porsche 4-cam racing engines used a similar design,
although they keyed theirs. But Still... Your Mileage May Vary.
Off Topic... Do not Archive
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418137#418137
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| Subject: | Re: Teaching vs. Propagandizing |
Most of us probably know this, but cantilever mounted engine pressure senders is
bad practice, steel or brass. I have personally seen steel ones break.
Tim
> On Feb 5, 2014, at 12:25 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
>
>
>> Robert, If I remember correctly, the fitting was brass. Broke off just about
flush with the oil pump housing. Which is right where the maximum vibrational
stress would have been applied.
>
> Bingo . . .
>
>
> Bob . . .
>
>
>
>
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| Subject: | Re: Electrical architecture with aux battery |
Bob,
I had looked at Z-10/8 but neglected to notice that your circuit uses one less
switch than mine. I should have known better than to try and improve on your
architecture. :D
Thanks for the reply.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418143#418143
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| Subject: | Re: Electrical architecture with aux battery |
When the alternator is off or has failed, the extra switch in my circuit would
allow powering the E-bus by only one battery at a time. I do not know if that
is an advantage or not. The more complicated a system is, the greater the chance
for pilot error.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=418144#418144
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| Subject: | Re: Teaching vs. Propagandizing |
At 03:04 PM 2/5/2014, you wrote:
>
>Most of us probably know this, but cantilever mounted engine
>pressure senders is bad practice, steel or brass. I have personally
>seen steel ones break.
>Tim
Yeah, those threads do offer a powerful stress
riser. Coming off a crankcase with a low mass,
soft overhang is probably never wrong.
Bob . . .
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| Subject: | Re: Electrical architecture with aux battery |
At 04:17 PM 2/5/2014, you wrote:
>
>Bob,
> I had looked at Z-10/8 but neglected to notice that your circuit
> uses one less switch than mine. I should have known better than to
> try and improve on your architecture.
Don't know that it won't happen yet . . .
but had you not exercised the idea it's
comparative value would never have been
tested. Good job.
Bob . . .
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| Subject: | Re: Electrical architecture with aux battery |
At 04:44 PM 2/5/2014, you wrote:
>
>When the alternator is off or has failed, the extra switch in my
>circuit would allow powering the E-bus by only one battery at a
>time. I do not know if that is an advantage or not. The more
>complicated a system is, the greater the chance for pilot error.
>Joe
That's a point to ponder . . . I'm still mulling
over light weight, no maintenance 'band aids'
to manage the brown-out, reboot problem.
Bob . . .
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| Subject: | Some data points and pictures from my Rotax 91X School |
Bob & others out there in aeroelectric land,
I have some pictures from the Rotax 91X school I attended back in 2006. They are posted on my Europa build web site. You can go directly to the school pictures with this URL: http://www.europaowners.org/main.php?g2_itemId=64472
The first set of pictures of a piston/con-rod are from that engine in which the
gentleman reversed the in/out fittings to the oil reservoir.
The next set of pictures are of the engine which had the oil pressure sender mounted
out on the extension to allow for a pressure switch. You can see the broken
brass fitting in the housing of the oil pump, a couple pictures of the holes
in the crankcase that the thrown rods made and an overview of the engine.
Which is now the demo engine used in the course.
As I said, I dont know if the engine seized in 10 seconds or 10 minutes, but Dean
said that if you interrupt the lubrication of the Rotax 91X engine it will
usually seize like that in 10 to 30 seconds. It does not tolerate loss of lube
at all well. And Im not going to test it on my engine. You can have a total
loss of the coolant and the engine will continue to run and will usually get
you to a safe landing at a reasonably close airstrip. It may never run again
after it gets you there, but it will get you there. You loose oil pressure and
you better find a flat spot quick because the engine is going to stop very
soon.
The Rotax 91X engine has much more in common with motor cycle engines than it does
with your normal Lycoming or Continental. The 914 turbo is 74 cu.in. and
produces 115 HP @ 5800 rpm. It is recommended that you limit this power setting
to 5 minutes max on take off. It uses a gearbox with a 2.43:1 gear ratio to
drive the propeller. The gearbox has a slipper clutch to protect the engine
in case of a prop strike. Because the engine and gearbox share the lube system
special oil is required. Most of the recommended oils are motorcycle oils.
But Shell does make an oil specifically for the Rotax 91X engine. The engine
has a dual Capacitive Discharge ignition, no mags. Normal operating range of
the engine is 5000 to 5500 rpm and you must keep the idle above 1400 rpm, preferably
above 1800 if you can. This saves wear on the gearbox. It has air cooled
cylinders and liquid cooled heads. It is a dry sump engine with separate
oil reservoir and oil cooler. Oil is returned from the engine directly to the
reservoir. From the reservoir it goes through the cooler on its way to the
oil pump. Purge the oil system after every oil/filter change. Never turn the
prop backward more than half a turn or you stand a chance of ingesting air into
the oil system and into the hydraulic valve lifts. This could trash your
valves. Always burp the engine before starting. (Open the oil reservoir, turn
the prop forward slowly to get compression on each cylinder, continue till all
the residual oil has been forced from the crank case into the reservoir. You
will get a distinct gurgle or burp when all the oil is back in the reservoir.)
This allows an accurate determination of the actual oil in the system and provides
some oil into the engine so you dont get a dry start. It has dual carburetors
which must be balanced for the engine to run smoothly. When the carbs
are properly balanced, the engine is extremely smooth with almost no vibration.
Almost like an electric motor.
All in all, it is a very good little engine. Lots of power for the size and weight
of the engine. I dont think anything out there can match the power to installed
weight ratio. A very efficient engine with a fuel consumption of about
4.5 gph at a 130 kt cruise in my Europa tri-gear. 5.0 gph will get you to 140
kts. You just can not treat it like your daddys Ly/Co. If you do, you will
probably hurt it.
I HIGHLY-HIGHLY recommend anyone flying behind a Rotax 91X engine attend one of
the Rotax operators schools. They are available from several Rotax shops in
the US and Canada.
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop (50 hrs).
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger@mac.com
Message 20
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| Subject: | Rotax crank failures |
>6) The ability to use roller bearings. (I have no idea if they
>actually should or do).
Interesting point to ponder . . . if they do use
roller bearings, then in no way will a loss of
lubrication put a destructive torque moment on
the crank end of the rod in a mere ten seconds
of running . . .
but no . . .
This excerpt from the 912/914 maintenance
manual . . .
http://tinyurl.com/mresg6r
suggests that the classic pressure
lubricated sleeve bearings are used on the
connecting rods.
Emacs!
>As long as the rod and main bearings are good, the idea that the
>crank can come apart is simply a distraction. Porsche 4-cam racing
>engines used a similar design, although they keyed theirs. But
>Still... Your Mileage May Vary.
. . . I've not heard of crank disassembly
in the field . . . those engines have been
around for a very long time. It's hard
to argue with success!
A short web-cruise did turn up this crank
failure accident
http://tinyurl.com/lzhk22s
which failed to identify any errors of manufacture.
The press-fit technology is not a high-risk
process. Interruption fits of highly stressed
parts has along history of success.
Also found an AD against a production batch
of Rotax 912 cranks for suspected vulnerability
to cracking.
All incidents of slipped assembly joints
I found were byproducts of prop strikes.
I think there's a slip clutch mod that
reduces probability of a prop-strike from
over-torque slipping of the joints.
All in all, a pretty clean track record.
do not archive.
Bob . . .
Message 21
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| Subject: | Change of business model . . . |
I was running short on several commodities and
checked back on how long the last replenishments
took to clear the shelves. It appears that I
could really use that cash and shelf space to
better advantage.
Back when Dr. Dee and I started merchandising
our work product and that of others, 50% of
our inventory rolled over about every 90 days.
90% in 180 days or less.
Now the roll-over is 3 to 4 times longer.
For low volume manufacturing to work at all,
it needs to be part of a larger stable of
activities that rolls inventory faster.
Before Dr. Dee finished her graduate work and got
a better job than I had . . . she took care
of most of the day-to-day activities on the
merchandising side. But she's busy with a
new job and my 'retirement' has been less than
free of opportunities to do what I do best.
As of this evening, I've closed the manufacturing
operations for the AeroElectric Connection. Return
on investment for the hammer-n-tongs operation is
poor compared to the writing/teaching/consulting
activities that have little overhead.
I'll continue to do the fun stuff (AeroElectric
List and seminars), get back on Revision 13
to the book, write for Kitplanes and exploit
some opportunities on the TC side of the house
as well.
I'm looking for a manufacturing operation that
would like to add current AEC original
designs to their stable along with a half dozen in
the wings that are stagnant simply because I
don't own/run a factory.
After current commitments are fulfilled, the
mechanism by which future product developments
are actualized will have to happen in somebody
else's shops.
Bob . . .
Message 22
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| Subject: | Re: Rotax crank failures |
=46rom the pics on the Europa site posted earlier, it clear they uses one pi
ece rods. Only way to do that is with roller bearings and a press assembled c
rank. The main bearings seen are typical automotive style Babbitt bearings.
Also the blueing on the rod beam shows the amount of heat generated when the
failure occurred.
Tim
> On Feb 5, 2014, at 6:41 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroel
ectric.com> wrote:
>
>> 6) The ability to use roller bearings. (I have no idea if they actually s
hould or do).
>
> Interesting point to ponder . . . if they do use
> roller bearings, then in no way will a loss of
> lubrication put a destructive torque moment on
> the crank end of the rod in a mere ten seconds
> of running . . .
>
> but no . . .
>
> This excerpt from the 912/914 maintenance
> manual . . .
>
> http://tinyurl.com/mresg6r
>
> suggests that the classic pressure
> lubricated sleeve bearings are used on the
> connecting rods.
>
>
> <34add2aa.jpg>
>
>
>
>
>
>
>> As long as the rod and main bearings are good, the idea that the crank ca
n come apart is simply a distraction. Porsche 4-cam racing engines used a si
milar design, although they keyed theirs. But Still... Your Mileage May Vary
.
>
> . . . I've not heard of crank disassembly
> in the field . . . those engines have been
> around for a very long time. It's hard
> to argue with success!
>
> A short web-cruise did turn up this crank
> failure accident
>
> http://tinyurl.com/lzhk22s
>
> which failed to identify any errors of manufacture.
> The press-fit technology is not a high-risk
> process. Interruption fits of highly stressed
> parts has along history of success.
>
> Also found an AD against a production batch
> of Rotax 912 cranks for suspected vulnerability
> to cracking.
>
> All incidents of slipped assembly joints
> I found were byproducts of prop strikes.
> I think there's a slip clutch mod that
> reduces probability of a prop-strike from
> over-torque slipping of the joints.
>
> All in all, a pretty clean track record.
>
> do not archive.
>
>
>
> Bob . . .
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