Cranking the engine by hand between flights

·         Olav Soendergaard Poulsen

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Hi Jabiru
In Denmark we have a quite rough coastal climate with high humidity and average temperatures during winter around 0-5 deg C and in summer around 20 deg C. I have owned my Jabiry engine for 1½ year and have been told the Jabiry cylinders can corrode inside if the engine is not run for some time. So if I have not been out flying for two weeks or so I crank the engine 15-20 turns by hand to distribute the oil inside the engine, and prevent corrosion to start inside the cylinders.
Now the other day another pilot told I should never do this, since it only add wear to the engine. If the engine is not run for a while I should spray preservation oil into th cylinder through the spark plug holes.
I have flown the plane more than 100 hours during the 1½ year I have owned it, and only a couple of times the plane has been idle for more 3-4 weeks.
What is your recommendation for care between flights? Do nothing or is it a good idea to crank the engine by hand if left idle for a few weeks?

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·         Doug Smith

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Hi Olav,
Corrosion in the cylinders is definitely a problem if the engine sits for too long. The engine Maintenance Manual recommends your procedure if the engine is to be idle for up to a month and to use an inhibitor sprayed through a spark plug hole if it will be longer than that (Section 7 of JEM0002).

The reason that the procedure changes is that turning the engine by hand will move around any oil that is in the cylinder bores - but it won't add any new oil. So eventually, by turning the engine you will actually move all the oil out of the cylinder, leaving it vulnerable to rust. The other thing I would add is that covering the openings to the engine - intake and exhaust - is very important when storing the aircraft.

Inhibiting the engine is not very convenient so it might suit you better, if you are not flying often, to start the engine, warm it and run it for a few minutes once a month or so. That way you will warm the engine and oil (which will help remove moisture from the system), charge the battery, clear out the fuel in the carburettor and check the ignition system, all in one go. Ground runs are definitely not ideal - temperatures may not get high enough or you may glaze the bores if the engine runs too long at low power - but can be an acceptable compromise between flying often and inhibiting the engine.

Regards,
Doug.

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·         Christophe BONAERT

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Dear Doug,

I had this problems with rust into cylinders. Now I found a perfect additive for oïl that prevent this .
I give you the name .. Cam Guard additive FAA approved available on Spruce Aircraft site. Since I am using this, oïl, spark plugs, and cylinder barells are in perfect state even if the plane is staying for a long period without flying.

Best Regards,

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·         Doug Smith

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Thanks Christophe,
I've not come across this one myself. What kind of climate do you have? A wet climate, near an ocean, is the worst for rust.

(As you know, Jabiru does not approve oil additives because we don't have the resources to verify all the claims made by the people selling the stuff. We have also found that some automotive additives can be very bad for the engine - so additives are used at the owner's risk.)

Regards,
Doug.

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·         Christophe BONAERT

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Hi Doug,
I live in a hot and humid climate, Madagascar, from time to time near the Mozambique Channel and the Idien Ocean.
I'm aware of the oil additives that your company has not approved, but in my case, it works well with mine ... I had two Jabiru planes and 3 engines, and maybe because of the poor quality of the aircraft. gasoline (AVGAS) that we have here, the cylinders were corroded and you know what happens to the segments ... they were stuck. Of course , with the GEN 4 engines it is not needed anymore ...
( aslcamguard.com/products-2/aviation-2/ )

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·         Tony Richardson

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Hi

Wouldn't Shell W100 Plus provide the same results as Cam Guard?

Its tested and approved for aero engines

I have used W100 Plus my 2200 engine since new (224 hours) to prevent problems with corrosion as it used to sit in a hangar with carpet covered dirt floors. (soggy in winter) No sign of cylinder rust the last time I inspected it with a led borescope.

www.shell.com/business-customers/aviatio...hart14-30071535.html 

Cheers
Tony

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·         Doug Smith

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Hi Tony,
W100 Plus is certainly better than regular W100 and it should be fine for a month or so - but it's not a dedicated inhibitor oil and it shouldn't be relied on for much longer than that.

I couldn't hazard a guess as to how it would perform compared to Cam Guard...

Regards,
Doug.