Cessna 172N Skyhawk
Broken Pushrod
The #3 cylinder exhaust valve pushrod broke due to a valve stuck in the closed position. No marks were seen on the top of the piston through a borescope. The lifter came apart as a result of the broken pushrod but appears to have been operating properly previously.
Part total time: 1567.0 hours
Cessna 172S Skyhawk SP
Abnormal Wear
During an unscheduled inspection, the #2 cylinder intake pushrod and rocker arm were found abnormally worn. (They were replaced 64.7 hours earlier.) The #3 cylinder exhaust pushrod and rocker arm also were abnormally worn.
Part total time: 64.7 hours
Cessna 172S Skyhawk SP
Excessive Wear/Oil Starvation
Due to a failed compression check on the #2 cylinder, a defective rocker arm and pushrod were discovered. All rocker arms and pushrods were subsequently inspected and excessive wear found. Defects appear to be due to oil starvation.
Part total time: 1117.0 hours
Cessna 402C Utililiner
Broken Pushrod
Pilot reported the left engine running rough in flight and oil pressure at zero. Inspection found metal contamination in oil filter, #4 cylinder intake push rod broken and a large gap at the exhaust rocker arm. The engine was replaced and sent to the manufacturer for analysis.
Part total time: 168.0 hours
Piper PA-28-181 Archer II/III
Extremely Worn Pushrod Ends
Customer reported trace metal in oil filter. Cylinders were removed from engine, and extreme wear was found on the pushrod ends and the rocker arm sockets. This wear seems to be a design flaw on Lycoming’s new-style roller tappet engines. It appears that not enough oil is reaching the top of the cylinders and the rocker arms.
Part total time: 565.0 hours
Piper PA-31-350 Navajo
Bent Pushrod
A few miles from the airport, the #2 engine began to run rough; the pilot performed a precautionary shutdown. Inspection revealed the #6 cylinder intake tube and pushrod were bent. While attempting to change the cylinder, it was determined to be damaged to the point of not being able to be removed from the crankcase. The #4 cylinder was removed and borescope inspection found a #6 connecting rod failure and internal damage.
Part total time: 1741.0 hours
Piper PA-44-180 Seminole
Abnormal Wear
During visual inspection, both engines’ rocker arms and the right engine #3 cylinder exhaust pushrod showed abnormal wear at rocker arm end.
Part total time: 1044.0 hours
