Failed Spark Plugs

The following is derived from maintenance facility submissions to the FAA’s Service Difficulty Reports database.

Sunday, December 24, 2023 at 08:00 AM ET

Verified

The U.S. Coast Guard has not yet located a missing Cirrus SR22T that was last tracked heading toward the Gulf of Mexico. Cirrus Aircraft

Key Takeaways:

Various spark plug defects, including missing ground lugs, out-of-tolerance resistance, and broken ceramics, are common causes of engine performance issues.
These failures can lead to severe engine damage, ranging from rough running and loss of power to preignition, holing of pistons, and complete engine replacement.
Several incidents highlight that spark plug failures can occur with relatively low operating hours, emphasizing the critical need for vigilant inspection beyond typical service intervals.

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American Champion 8GCBC Scout

Failed Electrode/Engine Damage

After a scheduled spark plugs change, pilot reported a rough engine with loss of power. Found lower plug in the #4 cylinder was missing the ground lug portion of the electrode. Inspection included cylinder borescoping, oil filter and screens. No contamination was noted. Champion REB37E plug replaced. About eight engine hours later, another rough engine event occurred, with no compression in the #3 cylinder and loss of oil. That spark plug was missing the same ground lug on the electrode. It appears the lug became lodged between the piston and ring, holing the piston and cylinder wall.