Pushrods

The number 3 cylinder exhaust pushrod broke, due to a valve stuck in the closed position. The valve was not stuck at the time of the investigation. No marks were seen on the top of the piston as viewed through a borescope. The lifter came apart as a result of the broken push rod but appears to have been operating properly prior to the event.

Editorial Staff

Wednesday, May 17, 2017 at 12:00 AM ET

Verified

Key Takeaways:

Multiple aircraft models experienced significant wear, damage, or failure of cylinder pushrods and associated rocker arms.
Common causes identified for these engine component issues included manufacturing defects (e.g., undrilled oil passages), insufficient lubrication, and secondary damage from a stuck valve.
An isolated incident also reported bent aileron control pushrods, suggesting potential ambiguities in maintenance manual guidance for control surfaces.

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Cessna 172N Skyhawk
Broken Exhaust Pushrod

Part total time: 1567.0 hours

Cessna 182T Skylane
Worn Cylinder Pushrods

Inspection revealed 10 of the 12 pushrods are worn. At 578.9 hours tach time, abnormal pushrod wear was noted when changing cylinder number 3. At 627.0 tach hours, the number 2 cylinder was replaced and all pushrods were re-inspected. All were found to have abnormal wear.

Part total time: 1971.0 hours

Cessna T206H Stationair
Worn Cylinder Pushrods/Rocker Arms

Inspection performed IAW SA-167A. Four pushrods and 4 rocker arms were found scored. All parts were replaced due to being worn beyond acceptable limits.

Part total time: 906.0 hours

Diamond DA42 Twin Star
Bent Aileron Pushrod

After receiving a report from another operator regarding an anomaly found with the aileron control rods, inspected the rod ends on our aircraft. Found rod ends on both the left and right ailerons bent. The rod ends appear to have been bent to accommodate the movement of the aileron but we cannot find a description of this process in the maintenance manual.

Part total time: 9.0 hours

Maule M5-235C
Defective Cylinder Pushrods

The number 1 cylinder intake and exhaust pushrods were not drilled through on one end. This defect would not allow oil to travel up the pushrod to the rocker.

Part total time: 1235.0 hours

Damaged Cylinder Pushrod
Piper PA-28-181 Archer II/III

Customer reported metal in oil filter. Extreme wear was found on pushrod ends and the rocker arm sockets. It appears that not enough lubricating oil is reaching the top of the cylinders were the rocker arms are located.

Part total time: 565.0 hours

Piper PA-44-180 Seminole
Worn Cylinder Pushrods

Inspection IAW SA-167 found cylinder numbers 2 and 4 intake and exhaust pushrods and rocker arms were abnormally worn. Number 3 intake pushrod and rocker arm also were abnormally worn.

Part total time: 1103.8 hours