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:

Physical failures of spark plug electrodes, such as missing ground lugs, can lead to catastrophic engine damage, including holed pistons and cylinder walls.
Electrical issues like out-of-tolerance resistance or open current paths in spark plugs frequently cause engine misfires, rough operation, and high ignition system voltages.
Spark plug failures can result in preignition, causing significant internal engine damage to cylinders, pistons, and bearings, often necessitating engine replacement.

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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.