Well, short of shutting down, removing the plugs and cleaning them, the only way to do it is by lean operation as you said.
But it’s highly aircraft/engine/plug specific. In my SR22, I haven’t had a single fouled plug in ten years and 1000 hours. And that is with massive electrode plugs.
boscomantico wrote:
Well, short of shutting down, removing the plugs and cleaning them
So you would cancel/postpone your flight for a direct intervention. I didn’t think it was necessary, but may consider the things again.
On the subject of cleaning plugs, you can sand blast massive electrode plugs but do not do this to fine wire plugs. They have to be ultra sonically cleaned. Trouble is I cannot remember why but I suspect it’s because the sand is too harsh for the fine wire electrodes.
I think it depends on the grade of sand used. I cleaned my URHM38S iridium plugs the other day, with the standard plug cleaner (sand and compressed air) and they came out nice, no damage to the electrodes.
As for leaning in climb, best to use the constant-EGT method – it’s described e.g. here
The “best power point” is more than 100F ROP but the curve there is fairly flat so it can be debated. What is harder to debate is where it lies when you are at FL200 and trying to climb another 100ft to stay above some buildups, the stall warner is going off… it is very obvious it lies 125-150F ROP then 
Peter, of course you CAN clean your iridium plugs with sand and they will look wonderful. But should you?
Very interesting indeed.
What about your personnal SOP in case you detect a fouled plug during your run up ?
(The last time it happened to me, I discovered that the previous short Low level flight had been conducted full rich)
Peter, of course you CAN clean your iridium plugs with sand and they will look wonderful. But should you?
here, page 13
The above is for Champion fine wire plugs. I cannot easily find the equivalent for Tempest fine wire plugs. There is some stuff on Autolite which IIRC are what Tempest bought but not fine wire.
Just found this from AOPA:
The easiest way to clean aircraft spark plugs is to use a special aircraft sparkplug cleaner. Your mechanic probably has one you can use, but if he or she doesn’t, you can purchase an inexpensive aircraft plug cleaner from any aircraft supply house. It’s a special, air-powered cleaner that lightly sandblasts the plug electrode and insulator. If you use a plug cleaner that’s not specifically design for aircraft plugs, it may be too abrasive and you can ruin your plugs. Be especially sure not to use glass-bead media. It can get embedded into the insulator gap and eventually cause arcing in the plug. This is especially true for fine-wire plugs, which should never be used in any abrasive cleaner. For massive plugs with heavy lead deposits, you can use a vibrating cleaner or a dental pick to carefully remove the lead. For fine-wires, Hoppe’s No. 9 cleaner and a dental pick should be all you need to remove the lead without damaging the insulator or the iridium electrode. Finally, the outside of the plug needs to be inspected and cleaned on the plug threads where the plug goes into the engine as well as the lead threads at the top, making sure along the way that the barrel well is clean and free of any moisture or debris.
I only pick out the lead with a dental pick, nothing else. Ultrasonic cleaner is best for iridium but only necessary if badly coked up.
STOLman wrote:
Hoppe’s No. 9 cleaner
Had to google that, I guess in the US everyone knows that product. :)
PetitCessnaVoyageur wrote:
Leaning during taxing is obviously the best preventive action, but how do you cure if that happens during the mag check ?
Don’t run full rich during runup, just enough to make it to the runup RPM.
