Rotax Sparkplugs

Is this a joke? You are not supposed to run your plugs for 200 hours! Between 25-50 hours max.

The 912 manual section 05-20-00 page 10 states that the plugs should be replaced at intervals of 400 h if unleaded fuel is used.  They should be replaced at intervals of 200 h if leaded fuel has been used for more than 30% of operation.   They should be removed and inspected at intervals of 100 h. 

Cracked porcelain can be a symptom of detonation or pre ignition.

Cracked porcelain is bad and they should be replaced. Plus it looks like someone used anti-seize on the plug threads instead of the thermal paste.

Mirek is correct on the Rotax plug time change.

Hello again!
The sparkplugs are installed with thermal paste of course...I can complete with additional information. We have had 3 912 before and every one has been working very well to the last hour. I had made the services and have never seen that type of damage. Perhaps sometimes on a single sparkplug.
 So my question is still...can it be bad quality? The sparkplugs we had earlier seems to be better or?
Interesting to hear if someone else had met the same problem.

Torleif Hiort