FOULED PLUGS CAUSE PRECAUTIONARY LNDG.

Narrative

AFTER A SUCCESSFUL PRECAUTIONARY LNDG DUE TO A PARTIAL LOSS OF ENG PWR; EXAMINATION OF THE ENG REVEALED THE CAUSE OF PWR LOSS. 2 OF THE SPARK PLUGS WERE LEAD-FOULED TO THE POINT THAT THEY WOULD NO LONGER OPERATE AND ALL OF THE LOWER SPARK PLUGS IN THE ENG HAD SOME DEG OF LEAD FOULING ON THEM. THIS FOULING OCCURRED VERY RAPIDLY IN FLT AFTER A NORMAL ENG RUN-UP; AND AFTER ONLY APPROX 20 ELAPSED FLT HRS SINCE THE SPARK PLUGS WERE CLEANED AND SVCED. LEAD FOULING OF ACFT SPARK PLUGS CONTINUES TO BE AN EVERYDAY PROB FOR ALL RECIPROCATING ACFT ENGS; SOME ENGS APPEAR TO BE MORE PRONE TO FOULING PROBS THAN OTHERS; BUT ALL ENGS WILL OCCASIONALLY FOUL THE SPARK PLUGS. IN THIS OBSERVER'S OPINION THE ONLY REAL CURE FOR THIS PROB WOULD BE LESS LEAD IN AVIATION GASOLINE; MAINLY 100 LOW LEAD FUEL; BECAUSE THE MANUFACTURERS HAVE TRIED VARIOUS MECHANICAL MEANS TO PREVENT THIS PROB SUCH AS CHANGING THE DESIGN OF SPARK PLUGS; ETC; WHICH HAVE NOT BEEN SUCCESSFUL IN PREVENTING THE LEAD FOULING PROB. THE RECENCY OF SPARK PLUG CLEANING AND SVCING SEEMS TO HAVE LITTLE TO DO WITH PLUG FOULING; AS MANY TIMES; PLUGS THAT HAVE JUST BEEN CLEANED WILL FOUL OUT PRIOR TO THE FIRST RUN-UP; LESS THAN 5 MINS ENG RUNT TIME. IN CLOSING; I DO NOT HAVE AN ANSWER FOR THIS PROB; BUT IT IS ONE THAT CONTINUES TO PLAGUE THE RECIPROCATING ACFT FLEET AND; AT TIMES; CAN BECOME A HAZARD TO FLT OPS. PERHAPS IT COULD BE ADDRESSED AT THE INDUSTRY-WIDE LEVEL TO FIND A SOLUTION FOR AN INDUSTRY-WIDE PROB.