Jabiru beach emergency landing. Gamtoos area.

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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by Joe S » Sun Feb 03, 2019 5:11 pm

crazeeflya wrote:
Fri Feb 01, 2019 9:45 am
Marius Schrenk wrote:
Thu Jan 31, 2019 5:57 pm
Sorry to hear about ESS Anton. Full open throttle should lead to less carb icing not more. a Jabbie is rigged to supply filtered carb heat so it might take a little longer to heat . However you could fly a Jabbie all day long with carb heat on with very little effect on the power it produce. As you eluded it is perfectly safe to do a go around with carb heat on. Not all Jabbies has the tenancy to carb ice though. The one's that does however are serial offenders. I suspect it might be due to airflow through the very tight cowling.I can honestly say I have never experienced carb icing on my Jabbie....but I live in the highveld. During the winter I normally use carb heat to enrich the mixture as they do not have a mixture control.
Agreed Marius, shortly after getting my licence, in typical midlands high humidity under the cloud base, I experienced violent vibration in my then Jab SP 2200; to the degree that I thought there was an engine break up in process - backed off throttle to try "save her" ...got worse....then the training penny dropped and I pulled carb heat...managed to nurse her over Pietermaritzburg central for a straight in landing on 16 PMB. Scottsville racecourse was looking really tempting at a point!! Lesson learnt.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by jimdavis » Sun Feb 03, 2019 9:11 pm

I am curious. If inadequate carb heating is a know problem on certain Jabby/engine combinations, why hasn't there been a mod?

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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by Redmoon » Mon Feb 04, 2019 6:40 am

Over the last year I have flown about 30 different Jabiru aircraft in all types of weather conditions. Not once did I experience carb icing. We get perfect days for carb icing at the coast. Engine management and proper basic training should most of the time keep you safely airborne. I hear a few people running the engines down but in defense of a great product, I have full confidence in a factory maintained Jabiru. The skill and workmanship down in George are top quality. I fly my family around regularly in these aircraft,and that’s from normally flying them in a KingAir. I have never experienced loss of power at sea level when using carb heat.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by jimdavis » Mon Feb 04, 2019 7:35 am

Redmoon wrote:
Mon Feb 04, 2019 6:40 am
Over the last year I have flown about 30 different Jabiru aircraft in all types of weather conditions. Not once did I experience carb icing. We get perfect days for carb icing at the coast. Engine management and proper basic training should most of the time keep you safely airborne. I hear a few people running the engines down but in defense of a great product, I have full confidence in a factory maintained Jabiru. The skill and workmanship down in George are top quality. I fly my family around regularly in these aircraft,and that’s from normally flying them in a KingAir. I have never experienced loss of power at sea level when using carb heat.

Greetings RM. I am being doff. Do you mean that there is some other problem when folks complain of loss of power, or do you mean that if you use carb-heat according to the POH there shouldn't be a problem? Genuine question.

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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by Flooi » Mon Feb 04, 2019 7:56 am

Redmoon wrote:
Mon Feb 04, 2019 6:40 am
Over the last year I have flown about 30 different Jabiru aircraft in all types of weather conditions. Not once did I experience carb icing. We get perfect days for carb icing at the coast. Engine management and proper basic training should most of the time keep you safely airborne. I hear a few people running the engines down but in defense of a great product, I have full confidence in a factory maintained Jabiru. The skill and workmanship down in George are top quality. I fly my family around regularly in these aircraft,and that’s from normally flying them in a KingAir. I have never experienced loss of power at sea level when using carb heat.
Ditto. Hundreds of hours in J430 as well as the 2200. Never had a problem in years...... I wonder about poor maintenance/technique?.
Last edited by Flooi on Tue Feb 05, 2019 6:24 am, edited 1 time in total.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by BigglesSA » Mon Feb 04, 2019 3:38 pm

jimdavis wrote:
Sun Feb 03, 2019 9:11 pm
I am curious. If inadequate carb heating is a know problem on certain Jabby/engine combinations, why hasn't there been a mod?

jim
Hi Uncle Jim

Jab has a good carb heat system. It has an advantage over some aircraft in that even the carb heat (also an alternative air source of sorts albeit hot) is also filtered. Heat shroud around exhaust muffler connected to a flip valve system on the filter box with some scud hose. Filter box connected to carburetor also with scud hose. Normal air is from naca duct on the cowl side to the flip valve with some scud hose. Pulling the carb heat opens the carb heat source and closes outside naca air intake by means of the flip valve on the air box. Simple as that.

Coming to think about it, I once had carb ice. Actually no, I had massive carb ice and that at cruise power setting near Rooiwal north of Wundertree.

As per training. Any non induced change in engine purr on Jabiru, fuel pump on carb heat out. Did not help so I did rather large opening and closing movement on the throttle and that almost put the fire out but after a few good throat clearing coughs she returned to a nice and even ear soothing purrrrrrr.

Never had carb ice before that and never had after that in almost a 1000 Jabi hours.

I also flew a very large amount of different Jabi variants.

Anton, I asked earlier, why do you think the crank is broken?
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by jimdavis » Mon Feb 04, 2019 5:53 pm

Thanks so much Francois. I am actually familiar with the system, and greatly applaud the fact that the hot air is filtered.

I am still not sure what's going on with various reposts of a drastic loss of power. Some folks didn't manage to keep the aircraft flying and others did, but only just, by using carb-heat. Carb-heat should do it's job swiftly and completely if used in good time. Is there a suspicion that the long drawn-out power losses are associated with the heat being applied too late?

Do Jabby engines use vacuum actuated slides/diaphragms in the carbs? and is it possible that the problems could be one slide sticking? Someone reported sudden and extremely violent vibration. That sounds much more like the loss of two cylinders, rather than carb icing.

Anyone any ideas on this?

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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by ZuluBen » Mon Feb 04, 2019 6:10 pm

Jim, on the Jab it is quite possible to detect carb iceing long before loss of power or even rough running occur.

It shows up as an imbalance between the left and right bank EGT's.

So on the old analogue guages, the needles go "out of balance", one goes high and the other one drops low.

On the digital guages, you need to look for the "Manhattan Skyline", with the EGT's alternatively high and low.

Carb heat at this time will sort the issue out before the pax are even aware of that.

And as Biggles said, in a Jab, if the engine sounds rough, only 2 things to do: 1) Carb heat ON, Aux fuel pump ON.

And you have to remember that by this time there is a LOT of ice that has to be melted, and that water has to go through the engine, so it will get worse before it gets better.

Sadly, the Destructors do not teach the Jab students the above... :shock: 8-[
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by dollar » Mon Feb 04, 2019 10:37 pm

I have often wondered why there isn't a little red light labled carb ice? I think I know the answer tho. How the hell do you measure it? EFI systems should be able to work it out however - but I wouldn't expect them to ice?

Maybe you need to measure humidity, then a profile of temperature, oxy sensor, TPI and RPM.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by dollar » Tue Feb 05, 2019 2:26 pm

They do make one. Using optics. Smart.

https://www.aircraftspruce.com/catalog/ ... etect2.php
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by heisan » Tue Feb 05, 2019 2:58 pm

dollar wrote:
Tue Feb 05, 2019 2:26 pm
They do make one. Using optics. Smart.

https://www.aircraftspruce.com/catalog/ ... etect2.php
All the MGL EFIS panels allow you to fit a temperature sensor to the carb, which then provides an ice warning when the carburetor throat temp reaches a preset limit.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by BigglesSA » Tue Feb 05, 2019 3:25 pm

heisan wrote:
Tue Feb 05, 2019 2:58 pm
dollar wrote:
Tue Feb 05, 2019 2:26 pm
They do make one. Using optics. Smart.

https://www.aircraftspruce.com/catalog/ ... etect2.php
All the MGL EFIS panels allow you to fit a temperature sensor to the carb, which then provides an ice warning when the carburetor throat temp reaches a preset limit.
Is it spoton real time Justin?
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by heisan » Tue Feb 05, 2019 3:29 pm

BigglesSA wrote:
Tue Feb 05, 2019 3:25 pm
Is it spoton real time Justin?
All depends on how/where you mount the sensor. Usually it is attached to the carb body, so there is some thermal inertia - so there is a delay for the temp inside the carb to reach the outside of the wall... If you can mount the sensor in the airstream immediately downstream of the main jet, then it will be pretty much immediate.
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by dollar » Tue Feb 05, 2019 9:07 pm

The link I shared actually uses an optical sensor in that it "sees" the ice. The carb temperature is relevant but that needs to be matched with humidity and I would guess ambient temperature. A specific mix of these parameters would lead to the onset of ice on a specific aircraft. It gets complicated.

I like the idea of an optical sensor. BUT have no idea of its effectiveness in practice? It reacts to the actual ice buildup - apparently :D
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Re: Jabiru beach emergency landing. Gamtoos area.

Unread post by Ugly Duckling » Tue Feb 05, 2019 10:56 pm

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