spark plugs for 912iS sport

Hi Kurt

The retail price of the Rotax plug is about 33 per plug, under 270 for 8.  If someone is trying to get 700 in the USA you are indeed being robbed. 

If you have experimental you can by aftermarket plugs but Rotax has not had supply of these for years.  Anyone selling them are suppling plugs from the motorcycle line.  

Cheers

PS, Roger and I argue about this everytime he brings up NGK.  NGK will not support any used in aircraft.  (that includes their connectors also) 

Kurt,

Both the new-style plug (Rotax 297 656) and the old-style plug (NGK DCPR8E) have the threaded stud. However, as Roger points out the old-style plug comes with a removable cap screwed on to the stud, whereas the new Rotax plug does not. 

Regarding the boots, both the old and new style boots are correct for the threaded stud type spark plugs, and they are both the same resistor value. The only differences are that the new boots are 90 degree (instead of 45 degree), and they are made of silicone rubber. The new boots hold up better and are (in my opinion) a legitimate upgrade. If your boots are 90 degree, they are the new style. Going by your photo, you already have the new style plugs.  

RW,

For this discussion, let's consider an SLSA. The service bulletin states that engines equipped with the older style plugs need not be upgraded. In your opinion, how does this apply to replacing the spark plugs once that is needed? Is it acceptable to buy and install the same plugs it came with, or is the intent of the SB to suggest that at the next replacement you would need to change to the new Rotax spark plugs?

If we are not supposed to replace like with like, that is not very clear by the wording in the SB. If asked, the SLSA manufacturer would likely refer us to the Rotax documents, so no help there. We know from this message board that this change was probably due to liability issues between NGK and Rotax, but the SB does not explain any of this, nor does it state that an owner would be out of compliance in any way by continuing to use the older style plugs. It would seem that an engine that was sold with the NGK spark plugs could continue to use them unless a mandatory bulletin was issued.  

I think Rotax would prefer that we upgraded to the new style plugs at the next replacement, but if so, why not state that and put an end to this question?

Jeff

Good points.  The matter as far as the factory is concerned at the time (2017) was NGK would no longer supply any product for aircraft use and Rotax had to stop supply.  If a distributor or service centre had a supply they were allowed to sell them down to zero.  Rotax from that point on only was able to use the new plug in production and then sold off inventories to zero.  

Now we are all reasonably smart and certainly know that there is no infinite supply coming from Rotax.  Anyone who told you they got NGK from Rotax after some 5 plus years is just telling a "fib" and I believe it is common knowledge that if you get them today they did not come via Rotax.  The fact that any spark plug box you get from NGK has a small aircraft with a red line across it should be a clue.  NGK does not want its plugs used in aircraft.  We are getting into territory like oil filters, there are approved and unapproved.  If you purchased NGK from a Rotax Service Centre and they claim they are approved from Rotax...big fib...They have not had Rotax NGK ones for years.  

I rather doubt us getting a listing added to the non-approved SL (like big bore kits, aftermarket starters, rebuilt crankshafts and the like) is going to stop people buying them or recommending them.  The lure of cheap parts is strong.  NGK was always a good plug so don't get me wrong.  If however approvals are not needed and the owner wants to buy them it is on them.  

When you go to the iPC today and look at the maintenance manual line today guess what?  There is no reference to the NGK at all.  That ship sailed is all I am saying.  

Cheers

example from IPC from 912/914 2021 edition and current

RW

"PS, Roger and I argue about this everytime he brings up NGK.  NGK will not support any used in aircraft.  (that includes their connectors also) " 😊

Yes, but it's always fun sharing ideas and thoughts.

Many thousands of Rotax engines still use NGK. NGK just didn't want the liability. Nothing wrong with the plugs especially since Rotax has used NGK plugs  longer than some of you have been alive. LOL

The new Rotax plugs are Bosch. With Rotax putting their name on them they now accept responsibility. 

When I buy spark plugs I buy 100 at a time. That last me about 90 - 100 days.