Experiences - Comparison "new" Rotax spark plugs vs NGK

To me the entire thing feels like a solution in search of a problem.  This is likely about corporate liability, and maybe a fortuitous trip to the cash register.  Ever heard of anyone having trouble with the old plugs?  Not likely, since most folks just run them for a year and replace them for $30.00. 

My aircraft is an SLSA, and I'm still unclear if using the old or new style plugs and caps would be better from an insurance and liability point of view. The new 90 degree cap may be a bit easier to pull test, but short of that, insurance and liability are the only metrics that could have any real consequence in this matter.  The performance of multi-electrode plugs has been tested for some time now, and finding any clear advantage is a stretch at best. 

Hi all

Perhaps this thread has run it's full course.  Seems to me that nobody cares what facts are anymore.  Simple truth is Rotax can't sell you NGK and can't support NGK because NGK forbids it.  Simple enough?  You can put in a tractor plug if you want, it is completely up to you.  The only spark plug supplier, for the aircraft engines, is the Rotax private label plug.  

And yes in 2017 Rotax had to change the head on the type 582 to fit the new smaller thread Rotax plugs due to the above noted NGK refusal to allow their plugs to be used.  There is an SI on it under the  582 bullitians.  

Cheers

Rotax Wizard,

It would be simple if the Rotax Service Instruction stated it just as you did, but they did not.  The SI states that engines with the old plugs don't need to be retrofit. However, replacement of the old plugs with the same type is not expressly allowed or forbidden. So it's left to the owners and mechanics to figure out that NGK does not want their plugs used in aircraft. Then to make it even more cloudy, the Rotax parts vendors are still offering the old style plugs without any disclaimer.  I don't think questioning these things means that any of us want to use a tractor spark plug, we just want to make the best decision with the information we have. 

Hello forum community,

Each response is an enrichment for the topic - thank you.
A small interim balance: Are there any comparison experiences - almost none! Why: the old engines may continue to operate with the NGK and NGK has worked to satisfaction. It would be economically nonsensical to use the more expensive spark plugs. The new engines are automatically equipped with the new Rotax spark plugs and for reasons of guarantee and warranty alone, no one dares to exchange them for the old NGK - cleverly threaded by Rotax!
Almost no experience - at least one (mine): I did not share my experience first because I wanted to start the topic open-ended. My experience: 912 UL (1500h) had to be replaced because the crankshaft block was stuck (probably in one batch the aluminum castings were not sufficiently tempered - not all 912 UL were affected - this is a long-term consequence and leads to rubbing together of the engine block). Old engine but good running, no vibrations, sufficient power! During a landing exercise with standing prop the starter could not move the crankshaft - after cooling down the engine everything was "OK" again.

New engine - absolutely no changes to the system - but slight vibrations (rough engine running) over the entire range of speeds and always uneven engine drop on the magneto check - 50 and 100-150 on the other ignition circuit! After eliminating all possibilities (really all that can have to do with vibrations - very expensive) I exchanged the Rotax spark plugs for the old NGK. Result: immediately the well-known soft engine run without vibrations.

The double-electrode spark plug from Rotax has negatively influenced the flame spred in my engine. The more ground electrodes the more the electrode shadow can affect ignition - which we also learned from this discussion.

Then the Rotax spark plugs complained - it was very difficult to get a new set of spark plugs (of course only on goodwill - the previous Rotax spark plugs had to be sent back) - result: exactly the same rough engine running. In my opinion the Rotax spark plugs will cause a shortened running time of the engine and some aircraft components in the long run, without being able to prove it. Maybe this is only my persoal problem or its affects only the 912 UL. Is there everyone who will make his own comparsion test?

Rotax could have solved its problem with NGK in a different way. Why always solutions that are to the detriment of the customer and to the advantage of the manufacturer? Is there no legal way to stop this arbitrariness? I myself know of two engine failures in my immediate vicinity where the cause is unclear - the carburetor or the fuel line must then hold out for a reason - that can not defend itself - no one asks about the spark plugs.

Thanks and Greetings!

Rotax Wizard wrote:

Hi all

Perhaps this thread has run it's full course.  Seems to me that nobody cares what facts are anymore.  Simple truth is Rotax can't sell you NGK and can't support NGK because NGK forbids it.  Simple enough?  You can put in a tractor plug if you want, it is completely up to you.  The only spark plug supplier, for the aircraft engines, is the Rotax private label plug.  

And yes in 2017 Rotax had to change the head on the type 582 to fit the new smaller thread Rotax plugs due to the above noted NGK refusal to allow their plugs to be used.  There is an SI on it under the  582 bullitians.  

Cheers

The above post is irrelevant to this discussion which is about whether the new very expensive plugs confer any advantages or disadvantages.

The fact of the problem with NGK did not force Rotax to change the style of plug. Presumably whichever manufacturer does now make the plugs for Rotax could have instead produced equivalents for the NGK types used which are simple basic traditional plugs.

For example, Champion list their type 809 as equivalent to the DCPR8E.  See

https://www.championautoparts.com/find-my-part/Part-Number-Results.html?part=dcpr8e and

https://drivcat.com/overlays/part-detail.aspx?brandId=CP&pNum=809&partType=