Surprise during Annual this week

[Yooper Rocketman]

I started the annual on the Rocket on Wednesday.  Right off the bat the first cylinder we compression tested (#5) after a good warm up would only make 20 PSI.  Didn't even waste time with the borescope as I could hear the air coming out the exhaust. We pulled it off and was pretty obvious the exhaust valve.  Ran perfectly normal the last flight so caught it at the right time.

Called Buldoc at 10:30 and had to leave a message with service manager.  Secretary advised they were very busy and never heard back until next day.  G&N said they could turn it around in two days so ND Air to them Wednesday afternoon.

Only the second cylinder in 2,000 hours ( not typical for TSIO520NB engine).  Since the oil filter was spotless the last oil change will keep running her until something surfaces telling me to pull it off for O.H.

Tom

[peevee]

Sucks, but I guess you can't complain at 2k hours.

[cliffy]

Just wondering if any thought was given to lapping the valve in place without removing the jug?

[N201MKTurbo]

My bosses A36 had the same problem. It had the same hours. It was time. The up side is it wouldn't make you crash. It is just the engine telling you it is time for an overhaul.

[jaylw314]

Sorry to hear that.  Out of curiousity, do you have engine monitor recordings leading up to this?  I'd be interested to see if you had the EGT spikes that Mike Busch suggests sometimes precedes exhaust valve failures.  

https://www.aopa.org/news-and-media/all-news/2014/july/08/savvy

"The symptom of an incipient failure is a slow, rhythmic EGT oscillation with a frequency of the general order of one cycle per minute and an amplitude of 30-to-100 degrees Fahrenheit"

Good luck with the new cylinder!

[sleepingsquirrel]

1 hour ago, cliffy said:

Just wondering if any thought was given to lapping the valve in place without removing the jug?

Could work if valve and seat isn't already damaged beyond repair!

14FN0000-ASI-Valve-Safey-Poster_Final.pdf

Edited June 10, 2017 by sleepingsquirrel

[Yooper Rocketman]

8 hours ago, cliffy said:

Just wondering if any thought was given to lapping the valve in place without removing the jug?

Since most my flying is pretty serious cross country (Upper Michigan to central Florida), my only thoughts were how much of an inconvenience this would be half way to Florida with the wife on board.  Then there's the cost on the road vs. me and my IA doing it in my hangar.  Choice gets pretty simplified considering those factors.  Not only that, some fellow Mooney Spacer may own this in less than a year.  I really didn't want to do a patch job.  Absent those factors, yes, I would have considered lapping the valve.

G&N reported back that the valve WAS bad and the valve guide was shot too after they tore it apart.  He was really surprised the jug passed rebuild specs, as the date code was one he was sure would be worn past limits.  Not sure if that's operator or dumb luck? 

Tom  

[cliffy]

Every choice has its plus and minus and I can't fault your choice given your perceptions of the possibilities. Lapping is just one tool in the box to be used at the appropriate time. 

[Andy95W]

And with the discoloration beginning on that exhaust valve (asymmetrical and turning green) it was starting to burn and not long for this world.  No brainer to me.

[carusoam]

Tom,

Great photo of the usual pizza image gone to something else... and fabulous description of the Compression test telling a different detail than usual...

Thanks for sharing those...

Hoping for a quick recovery...

Best regards,

-a-

[smwash02]

18 hours ago, cliffy said:

Just wondering if any thought was given to lapping the valve in place without removing the jug?

I've done this on mine when I've caught it early. His valve is already turning green at the edge, which would be pretty dangerous to keep running on.

[Bravoman]

12 hours ago, Yooper Rocketman said:

Since most my flying is pretty serious cross country (Upper Michigan to central Florida), my only thoughts were how much of an inconvenience this would be half way to Florida with the wife on board.  Then there's the cost on the road vs. me and my IA doing it in my hangar.  Choice gets pretty simplified considering those factors.  Not only that, some fellow Mooney Spacer may own this in less than a year.  I really didn't want to do a patch job.  Absent those factors, yes, I would have considered lapping the valve.

G&N reported back that the valve WAS bad and the valve guide was shot too after they tore it apart.  He was really surprised the jug passed rebuild specs, as the date code was one he was sure would be worn past limits.  Not sure if that's operator or dumb luck? 

Tom  

When you say that it reminds me how lucky I was last year to have my case go kaput ( as if there is any luck to be gleaned from the story!) as I was taking off from my msc's drome. I still shudder to think about the alternatives on that one!

 

regards, Frank

Edited June 11, 2017 by Bravoman

[RobertGary1]

On 6/10/2017 at 11:37 AM, Andy95W said:

And with the discoloration beginning on that exhaust valve (asymmetrical and turning green) it was starting to burn and not long for this world.  No brainer to me.

Idk. To me it's money down the tube for an engine already past tbo. I wouldn't have repaired it. 

-Robert

[N201MKTurbo]

On ‎6‎/‎9‎/‎2017 at 9:39 PM, cliffy said:

Just wondering if any thought was given to lapping the valve in place without removing the jug?

When the bosses engine started to have this problem we both did a lot of research into this. Most engine experts think that this is caused by worn valve guides, so re-lapping the valve would be a temporary fix at best.

[Yooper Rocketman]

On 6/13/2017 at 8:39 AM, RobertGary1 said:

Idk. To me it's money down the tube for an engine already past tbo. I wouldn't have repaired it. 

-Robert

You're flying an F, which was my last Mooney.  I bought it with 1900 hours on the engine (1996) and had to perform the oil pump AD at 2000 hours and a few said the same thing you just did.  The job cost me $500 and at that time an overhaul cost divided by TBO time put the cost of engine at $12 an hour.  I got 400 more hours out of it (worth $4800 in engine time) and sold the F with 800 SMOH.  The extra 400 that would have been on the engine had I rebuilt at 2,000 hours would have devalued the airplane another $4,000 at the time of sale.  So.......that $500 saved (or earned) me a lot of money.

The cylinder work will be under $2k.  With a 1600 TBO engine on the Rocket and recently substantiated overhaul costs on this list, engine time is worth $32-$40 and hour.  That means this is a break even investment at 60 hours.  The math seems pretty easy for me, especially when considering oil consumption (very low) and oil filter contamination (displayed in O.P.).  I guess if I was in the aircraft maintenance business I would hope for more aircraft owners with your opinion than mine.

Tom

[cliffy]

Just an observation NOT being picky (as mine is the same way) and it goes back as far as I can remember, BUT, why is it in every shop I go in, work in or even mine, I find all the shop work tables looking like the one under the cylinder picture? Well worn, stained and just ugly? I'm going to make a nice one with a white melamine plastic top so it looks neat and cool for my shop now!!! Make it look like an operating theater. Wipe it clean with a rag and WD40. I'll put a couple of black rubber door mats on it to cushion the cylinders I'm working on. .

[Yooper Rocketman]

6 hours ago, cliffy said:

Just an observation NOT being picky (as mine is the same way) and it goes back as far as I can remember, BUT, why is it in every shop I go in, work in or even mine, I find all the shop work tables looking like the one under the cylinder picture? Well worn, stained and just ugly? I'm going to make a nice one with a white melamine plastic top so it looks neat and cool for my shop now!!! Make it look like an operating theater. Wipe it clean with a rag and WD40. I'll put a couple of black rubber door mats on it to cushion the cylinders I'm working on. .

That IS what my main bench looks like (white Teflon).  The one in the picture is a "rolling bench" for holding tools and parts for disassembly work right by the airplane.  I don't put dirty parts on my good bench.  :>)  I also have two rolling benches with covers them, one carpeting, the other an old comforter.  My IA knew better than to put dirty parts on one of those benches.  

Tom

[RobertGary1]

7 hours ago, Yooper Rocketman said:

You're flying an F, which was my last Mooney.  I bought it with 1900 hours on the engine (1996) and had to perform the oil pump AD at 2000 hours and a few said the same thing you just did.  The job cost me $500 and at that time an overhaul cost divided by TBO time put the cost of engine at $12 an hour.  I got 400 more hours out of it (worth $4800 in engine time) and sold the F with 800 SMOH.  The extra 400 that would have been on the engine had I rebuilt at 2,000 hours would have devalued the airplane another $4,000 at the time of sale.  So.......that $500 saved (or earned) me a lot of money.

Tom

The hard part is knowing if you'll get 400 past TBO or 40. I've seen a few guys who have piecemeal'd themselves a full overhaul over the years but now can't claim 0 SMOH.

-Robert

[Yooper Rocketman]

1 hour ago, RobertGary1 said:

The hard part is knowing if you'll get 400 past TBO or 40. I've seen a few guys who have piecemeal'd themselves a full overhaul over the years but now can't claim 0 SMOH.

-Robert

That's fair.  I think my personal guidelines on managing high time engines SHOULD help me make the right decision.  I doubt I will look at another expensive investment before O.H.'ing.  Obviously I hope I don't end up with an "I told you so" (be it from you, or someone that thought the same but didn't say it).  

At this time, with the Lancair paint and interior expense looming, delaying the OH until I get past that expense (will likely be the cost of that OH or more) works better for my budget.

Tom

[Yooper Rocketman]

Finished the cylinder work and the Annual today.  The cylinder repair was well under my previous estimate so pretty happy with that.  Probably less than 40 hours to the break even point on that decision.  Did a good ground run and then cowled it up and did a 15 minute test flight.  Ready to fly some Young Eagles tomorrow. 

Definately a tight fit in the hangar now that Steve's E model got moved back in for a new prop and Avionics upgrades.  With the Basic Med he's going to start flying again.

Tom

[Hank]

Yaay, Tom! Two successes---your Mooney is up again, and Basic Med is getting another Mooney pilot back in the air!