Pushrod; defects and failures

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
We have all heard of failures of almost every part of an aircraft engine: cases, cranks, camshafts, gears, lifters, every part of a cylinder, every accessory, even oil pans.

Has anyone seen a pushrod fail through normal operation?
Especially in big bore continental engines?
Not during an interference event, that's the only time I've heard of them bending or breaking.

Has anyone found a defective pushrod either factory new or during a cylinder change?
I have not.

Just wondering, no specific event makes me think of this.
 
Heh.
 
Wow; not a single first-hand report, no link to stories, no photos of mushroomed ends or bend rods/damage to rocker arms & lifters.

Is this a component that we have not outsourced or have not forgotten how to manufacture?

Maybe there is something important here; something which could be transferred to the materials and processes we use to make all those other things (that fail on a regular basis) in engines?

What does the Continental Overhaul manual say about them, not a mandatory replacement part, no life-limit?
 
A part that nobody thinks of! Having helped build and rebuild gazillions of automobile-type stock and racing engines in my misspent youth, I have found that the pushrods themselves rarely fail without some forces way beyond what one would find in normal operations. I've removed them with scuff marks on the side from touching the head whilst in a bended state (missed shift in big block) and they still operated fine (as in didn't fall out, and still lifted the valves; they retained a tiny bit of bend and were replaced). The extremely low forces in our airplane engines don't stand a chance against the mighty pushrod; none were replaced in the two rebuilds I suffered through. I do recall a recall on some where a friction-welded ball-end wasn't fastened to specs, which could have been a mess, but that was a manufacturing issue.
Ultimately, they could be thought of as either "precisely built to withstand the forces encountered" or, more likely, "overbuilt".
 
After a top overhaul on a O-360, I noticed the engine running rough and pulled the cowling to feel the number two cylinder was cold.

I popped the rocker cover and noticed the exhaust valve rocker was tight and there was no compression.

There are a few different pushrod lengths available from Lycoming and it turns out that one was too long. It was fine for the five or so hours after the TOH, but then this happened.
 
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I've seen a lot of corrosion on the 0-200/0-300 steel tube pushrods.
 
Not on topic... I crewed on a AA/FS (that's a 499 CI Bonneville streamliner running on enhanced fuel) that had a single NA engine producing 2,400 HP on nitrous.

The pushrods were around .455" in diameter with tapered ends. :D
 
Let'sgoflying! said:
Wow; not a single first-hand report, no link to stories, no photos of mushroomed ends or bend rods/damage to rocker arms & lifters.

Is this a component that we have not outsourced or have not forgotten how to manufacture?

Maybe there is something important here; something which could be transferred to the materials and processes we use to make all those other things (that fail on a regular basis) in engines?

What does the Continental Overhaul manual say about them, not a mandatory replacement part, no life-limit?
Click to expand...

I have seen it once a couple decades ago. Not my plane and no reason to photograph.
 
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