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Jabiru Bad experience

Old 23rd Aug 2015, 21:14
  #141 (permalink)  
 
Join Date: Apr 2005
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Originally Posted by no_one View Post
I doubt that the new rotax 915 will be $40k. The 914 is 28k US and the new 915 will be at least $5k more. add shipping, GST and convert to aussie and you will be north of 50k.

Add a prop to deal with the new power, the cost to install it all and you will endup with a very expensive aircraft. A 912s on the other hand makes some sense.
Unfortunately the 912s is a little underpowered for the J430 which limits options to the Camit at circa 130 hp, the 914, 915 or something else...

http://www.aircraftkits.com.au/jabiru_conversion.html

Should be adequate for the [email protected] however.

The 915 and CSU prop are a ridiculous amount of money for any aircraft. They make the Lycomings look cheap as chips.
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Old 23rd Aug 2015, 23:41
  #142 (permalink)  
 
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I've heard of Rotax installations in Jabiru airframes. I have actually met someone who claims to have flown one. I have seen a photograph of a J160 purporting to have Rotax 912 installed in it...but I have never actually seen one of these aeroplanes, nor have I seen any review of the performance (or possible lack of it), or the pros and cons of the installation, etc etc etc. Additionally, it is only an option (if it is viable) for home-builders.
In 2011 I took a lesson (out to the coast, and a couple of circuits at YWVA) in a 24-registered (ie "factory-built") J160 with a 100hp rotax in it. It was a very pleasant plane to fly (but note that this was only the third type I had ever flown). Performance was very acceptable, and definitely better than the J160s with the Jabiru 2200c. I don't remember any strong nose down tendencies.

Mind you, this was a single hour lesson 4 years ago so my memories might not be completely unbiased. My memories of it are definitely better than my current experience of J160s (underpowered).
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Old 18th Jul 2016, 19:07
  #143 (permalink)  
 
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Two engine failures in one flight, the second one to the ground (airfield)

So,

I had an interesting day with a 'new' plane (microlight) - and am trying to figure out what might have happened. Help appreciated.

I'll bullet point the bits I think important...

• Avid Flyer 4, in great condition.
• Jabiru 2200, in great condition.
• Flight across Alps, south to north.
• Average altitude 9000’, maximum 12K.
• 4 hours.

Took off as normal, but only after a weird whistling on the comms – stopped by removing the aircraft power supply and relying on the 9v battery inside.
After 3 hours, engine started running roughly, occasionally. Carb icing suspected but carb heat had no effect.

Suspected choked/choking mags (no leaning option on this one) – so attempted to lean with fuel tap. Fairly difficult – several donkey stops before I found the point on the tap (only 90 degrees between open and closed!) – but again, no real change/improvement.

Problem increasing – so I increased RPM (from 2600 to 3000) and engine ran faster than for a normal cruise but smoothly, EGT etc. all okay.
Then, silence. Long let down to valley floor (doing all the usual things) engine restarted (by itself) at about 500’ agl – I’d have made my field I think…

Nearest airfield 10 minutes away (long 10 minutes!), engine running smoothly. Made a very tight circuit and once on base reduced power – engine cut. Landing made. Tried to start engine immediately, but barely turned over then clicking from starter (typical weak battery noise). Pushed plane to taxiway and apron…

Closer analysis with a multimeter, battery reading 12.1V and once engine started with external power there was no change to this figure with RPM movement. The aircraft has no electrical system indicators.
30 years flying, and I get two engine failures in one flight!

Answers on a postcard?

Fly safe, Sam.
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Old 18th Jul 2016, 21:18
  #144 (permalink)  
 
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A bit of the 'pucker factor' in that experience, was there, Sam?
Not being a techie, I'm not able to contribute but I'll watch this one with interest.
Good to hear it ended without tears.
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Old 18th Jul 2016, 21:40
  #145 (permalink)  
 
Join Date: Aug 2004
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I love a good mystery!

"whistling" = AC voltage from failed or partially failed alternator rectifier? little or no battery charging?

gradually weakening battery voltage reduces sparks at plugs?

After shutdown, battery has enough time for recovery just enough to give you sparks again at 500'?

Why not at least an ammeter light?

Alternative: failing ignition module?
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Old 18th Jul 2016, 22:05
  #146 (permalink)  
 
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Suspected choked/choking mags
Sam please send a photo of the mags as installed.
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Old 18th Jul 2016, 23:14
  #147 (permalink)  
 
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Hi Sam,

A few notes for you...


Carb icing suspected but carb heat had no effect.
Make sure you leave it on for a while and don't just pull on and then off fairly quickly.

Suspected choked/choking mags (no leaning option on this one)
The Jabiru engine has dual ignition coils. It does not have traditional magnetos. As the magnets on the flywheel pass the coils, a spark is generated. In theory no battery power is required, however the battery is required (a flat battery is ok) to complete the circuit. When you talk of "choking the mags" you are talking of fouling spark plugs. Indeed this is possible (whilst fairly unlikely) with the Jabiru / bing carby configuration, particularly at high altitude as the bing carby is not altitide compensating. It allegedly is to an extent but practical experience says otherwise. Who knows how your needle and main jet are configured... potentially it's set as rich as hell and you were very rich up top which should show up with rough running. If that's the case, you'll be so rich that you'll be washing your cylinders with fuel and causing excess wear to your rings and cylinders.

so attempted to lean with fuel tap. Fairly difficult – several donkey stops before I found the point on the tap (only 90 degrees between open and closed!) – but again, no real change/improvement.
You could be safely assured that this is not a great idea. What you're doing is running the carby bowl out of fuel and then drip feeding from the tap. If you believe you had a flat battery you'd be in strife if the engine stopped on you!

Problem increasing – so I increased RPM (from 2600 to 3000) and engine ran faster than for a normal cruise but smoothly, EGT etc. all okay.
Then, silence. Long let down to valley floor (doing all the usual things) engine restarted (by itself) at about 500’ agl – I’d have made my field I think…
How did the engine start by itself, was it turning over during the descent? Sure, if it turns over fast enough 280rpm approx, it will indeed start if the ignitions are on.


Closer analysis with a multimeter, battery reading 12.1V and once engine started with external power there was no change to this figure with RPM movement. The aircraft has no electrical system indicators.
30 years flying, and I get two engine failures in one flight!
Sounds like your stator isn't working and you simply aren't getting charge. It's pretty common for the two wires that come out of the stator to touch and short out as the plastic covers on the spade terminals are a very soft clear plastic and they rub and melt through. Either that or you have a wiring issue elsewhere. Check the wires running from the stator to the regulator. The light blue 16 gauge wires are the ones that are connected to the stator.

Consider fitting an AMPS meter or a volts meter as a minimum. There are plenty on EBay, in fact some simply plug into a cigarette lighter socket - can't get much easier than that.

If you are regularly going to fly at high altitudes and you already have EGT gauges, I recommend fitting a Hacman mixture controller. It's a needle valve on the dash with a couple of plastic hoses - one is tapped into the carby vent line and the other to the vacuum under the carby. You will then be able to lean your mixture at higher altitudes which will not only keep the EGT's the same as sea level, but also reduce fuel consumption and premature wear (as above). I have one and it works brilliantly. Very easy to fit and if you buy their version perhaps around $200. You could do it yourself by using hose and a dentist style needle valve with tap - all available from Ebay.

Last edited by Squawk7700; 18th Jul 2016 at 23:25.
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Old 18th Jul 2016, 23:39
  #148 (permalink)  
 
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so jabs have mag coils, does this exonerate the battery?
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Old 19th Jul 2016, 02:42
  #149 (permalink)  
 
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The Jabiru engine has dual ignition coils. It does not have traditional magnetos. As the magnets on the flywheel pass the coils, a spark is generated. In theory no battery power is required, however the battery is required (a flat battery is ok) to complete the circuit.
First part is correct. Second part is not unless this particular aircraft has a non Jabiru wiring arrangement. On a standard Jabiru the battery can fall out of the plane and the engine will run normally till the fuel runs out.

As this aircraft is not a Jabiru (only it's engine) a few questions come to mind:-

Why cruise at 2,600 RPM when Jabiru recommends 2,850 - 2,950 RPM ? Jabiru does not recommend cruising at 2,600 revs You can run it at higher than 2,950 revs but it will chew fuel.

Does the aircraft cruise fast enough to provide adequate cooling?

Are cooling tubes installed to direct cool air onto the ignition coils as called out in Jabiru aircraft? If you don't have them the coils can overheat and run intermittently.

When you went to 3,000 revs did you return the fuel tap to full flow? If you didn't the fuel flow wouldn't have been enough to keep the engine going.
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Old 19th Jul 2016, 04:48
  #150 (permalink)  
 
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First part is correct. Second part is not unless this particular aircraft has a non Jabiru wiring arrangement. On a standard Jabiru the battery can fall out of the plane and the engine will run normally till the fuel runs out.
Correct you are. I didn't go into too much detail as you generally need the battery to start it :-)

I had discounted the coils breaking down because they generally don't go U/S at the same time. I find with dodgey ones that they start to run rough about 5 minutes after takeoff (and over a certain RPM - around 2,800+ usually) and even though they are redundant, you can still notice things aren't going well when one of them is misbehaving.

The issue described smells like the stator but I'm at a loss to know why it would have stopped the engine. Doesn't sound like fuel, but does sound a little like coils, but being redundant... not sure.
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Old 19th Jul 2016, 22:18
  #151 (permalink)  
 
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Warning. Thread drift but still relevant.
Over the last 12 months for various reasons there has been dramatic increase in compliance to the Service bulletins/ Letters and maintenance procedures issued by Jabiru This combined with Jabiru engine training workshops has resulted in fewer incidents and has put Jabiru engines well ahead of Rotax for reliability, the standard by which CASA based their aggressive actions.
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Old 20th Jul 2016, 06:59
  #152 (permalink)  
 
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does anyone have numbers for the Jab fleet in the last 2 years?

Last edited by Ultralights; 20th Jul 2016 at 08:47.
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Old 20th Jul 2016, 08:58
  #153 (permalink)  
 
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Majority of engines with problems were in flight training........all maintained by L2 or LAME
Self maintained others saw very few problems. Older versions even less

I heard 7000 engines, 2000 Jab airframes
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Old 20th Jul 2016, 10:12
  #154 (permalink)  
 
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Majority of engines with problems were in flight training........all maintained by L2 or LAME Self maintained others saw very few problems. Older versions even less
Jetjr, I think you have this backwards. Flying training has a far better record than owner maintained. The private self maintained ones I have seen seldom do 500 hours between major work. The ones in the flying school I worked for regularly reached 1000 hours untouched and were returned to the factory for an exchange in lieu of doing a top end overhaul. Ditto for other flying schools that I know that operate Jabs

Using a Jab engine daily seems to be good for reliability. Ones that sit in hangers for weeks or months at a time don't seem to last many hours. Outdoor storage with infrequent use is a recipe for early failure.
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Old 21st Jul 2016, 05:06
  #155 (permalink)  
 
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(Over the last 12 months for various reasons there has been dramatic increase in compliance to the Service bulletins/ Letters and maintenance procedures issued by Jabiru This combined with Jabiru engine training workshops has resulted in fewer incidents and has put Jabiru engines well ahead of Rotax for reliability, the standard by which CASA based their aggressive actions.)

Surely you jest (If your comparing 912/914 4 stroke and not two stroke)
Absolutely no comparison,, the Rotax beats them hands down no question.
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Old 21st Jul 2016, 06:44
  #156 (permalink)  
 
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Hi Zac, can you please provide a link or cite the evidence that suggests that Rotax are "hands down no question" are more reliable than Jabiru engines?

Thanks.
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Old 21st Jul 2016, 06:48
  #157 (permalink)  
 
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i think the ATSB has some data on engine failures by type per 100,000 flight hours.
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Old 21st Jul 2016, 07:10
  #158 (permalink)  
 
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That's the data that is a problem... it's the skewed data that CASA used to put limitations on Jabiru engines that included fuel exhaustion and other non-engine related stoppages.

The blue text above has been quoted from Jabiru directly in an email that went out to operators. They have been working closely with CASA and the ATSB to go analyse the information and to carefully monitor each and every failure and document it, including since the release of said data. The result of this has been a more accurate set of statistics that I believe based on what I've heard from higher sources will prove what is written above.

At a guess, we are not likely to see an update of these statistics any time soon, just through regular reporting.
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Old 21st Jul 2016, 10:39
  #159 (permalink)  
 
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No Bob its from Jabiru/casa/atsb themselves and is built into most recent head inspection SB
Majority of engine failures were in flight training aircraft, mostly 4 cyl and almost all hydraulic lfter type

The link with poor maintenece is misleading. This problem is that concept forms the basis of keeping restrictions on experimental and modified aircraft. They have to "upgrade" to latest spec to hve them remove I think

Last edited by Jetjr; 21st Jul 2016 at 10:52.
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Old 21st Jul 2016, 22:58
  #160 (permalink)  
 
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S7700,,
2200 hours training and mustering in a 912 trouble free while I watched the Jabber's fail one after another with very low hours. But I won't fly a 2 stroke either !!
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