Replacement Time for New Rotax Spark Plugs

Rotax-Owner wrote:

In essence, the issue boils down to NGK's unwillingness to allow their plugs to be utilized in aircraft engines, which compelled Rotax to cease their sales and provision of NGK plugs with their engines. As a result, Rotax had to pursue an alternative path by introducing its own branded spark plugs to avoid encountering a similar situation in the future. Due to the relatively low demand for these plugs, Rotax has been left with little choice but to set higher prices. It is worth noting that NGK spark plugs had been used in Rotax engines since the early 80s, and they would likely have continued to do so if NGK had not intervened.

Additionally, it is worth mentioning that the NGK plug caps are not compatible with the new style spark plugs. To use the new style ROTAX spark plugs, it is necessary to switch to the corresponding new style plug caps. This is an important consideration for anyone using or planning to use the new spark plugs in their Rotax engines.

Furthermore, this issue extends beyond just spark plugs and encompasses other branded components used in Rotax engines. Carburetors, specifically those from BING, are also a subject of discussion regarding the rising prices of parts. Rotax not only had to develop its own brand of carburetors but the entire industry itself is transitioning away from carburetors, resulting in lower production volumes and increased prices for components. This trend has contributed to the challenges faced by Rotax and the overall pricing situation in the market.

The Note from SI-912-027 reads "In case of interchange/repair/maintenance it is not allowed to exchange individual parts. Mixing of spark plug types and spark plug connector types is not allowed. All spark plugs and spark plug connectors must be of the same part number for the entire engine."

The spark plugs and connectors (obviously) have different part numbers. Hence, I read this as all connectors must have the same part number, whether new or old style. And all spark plugs must have the same part number, whether new or old.

I see no prohibition in this service instruction of using 8 new style plugs with 8 old style caps.

Is there another reference that states this explicitly?

Although the above explaination to the new plugs makes sense, it is not the official explaination on the SI-912-027_SI-912i-013_SI-914-028-new plugs. The explaination there is: 

"Reason

In the course of continuous development and standardization, a new spark plug (part no. 297656) and new spark plug connector (part no. 265249) has been introduced."

In addition, the new plugs fit the old connectors (we replaced plugs only) which were redesigned to:

"New spark plug connectors:

Spark plug connectors now have a 90o angle, which have a slight influence on the outline of the engine shape and simplifies the measuring of pull-off force."

The NOTE statement reiterates that the use of old-style plug caps with new-style spark plugs is not allowed. It emphasizes the need to replace both the spark plug caps and plugs with the new style throughout the entire engine. Mixing old and new components, such as having a combination of three new caps and plugs with five old-style plugs and caps, is prohibited. This clarification can be found in multiple sections of the bulletin.

NOTE: In case of interchange/repair/maintenance it is not allowed to exchange individual parts. Mixing of spark plug types and spark plug connector types is not allowed.  All spark plugs and spark plug connectors must be of the same part number for the entire engine. 

1.3) Reason:  In the course of continuous development and standardization, a new spark plug (part no. 297656) and new spark plug connector (part no. 265249) has been introduced.  

This is the standard explanation provided whenever Rotax makes a modification or update to a part or component, as stated in all Service Instructions released by Rotax.

If you have any doubts or uncertainties about the information we have provided, we encourage you to reach out to your local Rotax Distributor or Service Center. They will be able to offer further clarification and address any questions or concerns you may have. - https://dealerlocator.flyrotax.com/

The NOTE simply doesn't say that, unless one interprets it as "all spark plugs and connectors must have the same part number". If so, flying is prohibited. Assuming this wasn't the intent, "all spark plugs must have the same part number" AND "all connectors must have the same part number" is the logical interpretation.

I've searched the OM, LMM, and HMM for any statement prohibiting the use of a set of old-style connectors with new-style plugs, or the opposite, and have yet to find a prohibition or caution against doing so. Can you provide any documentation besides the NOTE showing such a prohibition exists?

Don’t clean spark plugs with glass bead blasting or standard soda basting. Most blasting abrasives are too small and will eat away at the cement around the insulator and become lodged there.  You need to use a specific (larger) abrasive that won’t penetrate these areas. Also, walnut shell abrasive works well.  Here is a good document about this.  

https://tempestplus.com/wp-content/uploads/2019/01/Sparkplug-Cleaning-The-Right-Way-081412.pdf

Aircraft Spruce and others sell both the basting type and vibratory type spark cleaners at a reasonable price.