This could have ruined my day and then some!

[Joe Larussa]

Was doing my run up prior to departing to fly over the Sierras on the way to Reno. Advanced throttle for the run up and engine started running real rough. I'm thinking fouled plug maybe? Advanced one more time and thought oh hell no. Pulled the cowl and found the two nuts that hold a plate on cylinder 4 were gone and the intake rocket arm shaft had left the cylinder through said hole! I am pissed but glad it happened on the ground. Engine was overhauled one year ago and has 180 hours on it. Just came out of annual three weeks ago. Thoughts on who you might point your disappointment at?

[Guest]

Both, but whoever did the annual more so.  There must be an interesting story, where is the cover, the lock washers and nuts?

Clarence

[Oldguy]

Any flight time between annual and this? If so, very glad it did NOT happen on the previous flight.

Any sign of missing parts in the bottom cowl or on the engine?

[carusoam]

Would have thought oil would be running out all over the place...?

Best regards,

-a-

 

[Joe Larussa]

We found the plate and one nut on the cylinder. 

[Guitarmaster]

Dang!!!


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[Danb]

48 minutes ago, Joe Larussa said:

We found the plate and one nut on the cylinder. 

Wow!

[takair]

2 hours ago, Joe Larussa said:

We found the plate and one nut on the cylinder. 

Could you see any evidence of lock washer markings on the nut?  I too am surprised there was not some oil leaking.  Any damage to the rocker or anyplace else?

[MyNameIsNobody]

So glad that worked out for you.  Man, THAT would of left a pit in my stomach.  I look forward to hearing the chain as it unfolds.  Somebody really failed you here.

[aviatoreb]

Thank goodness for the run-up.

Goodness and thank you found it on the ground.

Is this overhaul still under warranty?

[Joe Larussa]

39 minutes ago, takair said:

Could you see any evidence of lock washer markings on the nut?  I too am surprised there was not some oil leaking.  Any damage to the rocker or anyplace else?

We only found one nut and the plate. Didn't look at the nut for washer marks. After much investigation it looks like the only damage was the rocker arm. Had a little gouge in it. Will order a new one Monday and install. 

[Joe Larussa]

3 minutes ago, MyNameIsNobody said:

So glad that worked out for you.  Man, THAT would of left a pit in my stomach.  I look forward to hearing the chain as it unfolds.  Somebody really failed you here.

I'm still in shock in many ways honestly. Twenty more minutes and I would be putting it down in the mountains. I'm happy and pissed at the same time!

[DAVIDWH]

Buy a lottery ticket.

With luck like that, you can't lose.

[Joe Larussa]

4 hours ago, M20Doc said:

Both, but whoever did the annual more so.  There must be an interesting story, where is the cover, the lock washers and nuts?

Clarence

Hey Clarence, are these nuts that you would check at annual and mark?

[Guest]

5 minutes ago, Joe Larussa said:

Hey Clarence, are these nuts that you would check at annual and mark?

Hi Joe,

The nuts are not specifically listed on an inspection sheet, (as in "inspect rocker shaft cover nuts for security") however a general inspection of the cylinders should have revealed loosened or backed off nut or nuts.  They would not normally be marked with inspectors lacquer.

The cover plate in question is immediately beside the fuel injection nozzle and line on the cylinder which does have a recurring 100 hour inspection AD so someone's eyes must have been looking there.

Clarence

[jetdriven]

They are just plain nuts with internal Tooth star washers. The 3 most common ways they would have come loose is they didn't have lock washers, the lock washers were re-used, or they weren't torqued down to begin with. 

[Guest]

Or someone was doing some maintenance and didn't finish it.  Some questions for the shop/maintainer to answer.

Clarence

[cbarry]

As a precautionary measure, I would absolutely check the other plates' nuts.  Heck, you might consider taking some time (or have a solid mechanic) and just go over the entire engine, motor mounts.... 

[Guest]

10 hours ago, Joe Larussa said:

We only found one nut and the plate. Didn't look at the nut for washer marks. After much investigation it looks like the only damage was the rocker arm. Had a little gouge in it. Will order a new one Monday and install. 

Joe,

I'm not sure, but I think you may have to remove the cover on the exhaust rocker for cylinder 2 in order to remove and replace the shaft.  In that case you'll need an extra gasket and lock washers.

Clarence

[Yetti]

Engine builder.  Would have to change out the length of push rod to correct length after putting the cylinders on.  The nuts have no pressure on them.  The nuts have been loose a long time to have the nuts fall off, then work the rocker arm rod out the hole.   Check all the other nuts.

[Yetti]

Not part of annual.   The annual would probably not re torque cylinder head bolts either, or accessory bolts or other bolts on the engine.

[Guest]

We don't know if there was any maintenance on the rocker shaft cover plate since the overhaul.  We do know that it just had an annual inspection.  The fuel injection injection line immediately beside the cover should have been inspected per AD 2015-19-07 at 100 hours since the engine was installed and again at the recent annual inspection.  This provided someone at least a few opportunities to spot this, as well there should have been a few oil changes along the way offering further chance to spot this.

Clarence

[Joe Larussa]

20 minutes ago, M20Doc said:

We don't know if there was any maintenance on the rocker shaft cover plate since the overhaul.  We do know that it just had an annual inspection.  The fuel injection injection line immediately beside the cover should have been inspected per AD 2015-19-07 at 100 hours since the engine was installed and again at the recent annual inspection.  This provided someone at least a few opportunities to spot this, as well there should have been a few oil changes along the way offering further chance to spot this.

Clarence

No maintenance on the cover has been done. I can say all the other nuts were tight. Some tighter than others however.

[Yetti]

33 minutes ago, Joe Larussa said:

No maintenance on the cover has been done. I can say all the other nuts were tight. Some tighter than others however.

Good mechanics can get things properly torqued without a torque wrench.    Would they ever do a propeller without one, No. sounds like they made it half way through the covers and then went to lunch.  The experience comes from going too far and having to extract a bolt.   I introduced a new term to my mechanic when he was going through the hoses.  "Tractor tight"  You snug it and then give a "ummph" to the wrench. 

I never use a torque wrench on my bike and have never had anything fall off.   Also the process of double checking your work was something that was not happening at the engine builder if they are all different torques.

If one had fallen out, I would have gone through the whole engine and figured out the torque values for each and every cover.  all 14 of the them and then called the engine builder.

[Joe Larussa]

13 minutes ago, Yetti said:

Good mechanics can get things properly torqued without a torque wrench.    Would they ever do a propeller without one, No. sounds like they made it half way through the covers and then went to lunch.  The experience comes from going too far and having to extract a bolt.   I introduced a new term to my mechanic when he was going through the hoses.  "Tractor tight"  You snug it and then give a "ummph" to the wrench. 

I never use a torque wrench on my bike and have never had anything fall off.   Also the process of double checking your work was something that was not happening at the engine builder if they are all different torques.

If one had fallen out, I would have gone through the whole engine and figured out the torque values for each and every cover.  all 14 of the them and then called the engine builder.

Maybe a dumb question but these were factory new cylinders. Can I assume then they were installed by Lycoming? Not to say the overhauler shouldn't double check.