Sorry, had too many glasses of wine when I wrote that and was too confrontational. Didn't mean to imply that 421 owners are suckers by any means. Wrong wording. I should have said that it just makes it less financially advantageous, that's all.

Hah. I can't even tell you how many spreadsheets I have for 421C vs Mu-2 vs C90 vs 501. None fit the "expense reduction specialist" moniker, though...

The left side of the main spreadsheet started with 182, I skipped over the P210 and Aztek columns, and I'm slowly marching to the right. I guess it's time to increase the flow into the top of the bucket...

The OP asks about Cessna and here comes the MU2 and Commander cheerleaders.
A couple positive comments by other posters about how this topic has stayed the course but some folks just want to change it.

Maintaining a GTSIO-520 and a TPE331 are not a lot different in price.

Don't forget the exhaust system on the twin Cessnas. By AD, it has to be inspected when the engine is overhauled, and that can be $10-20K a side depending on what is wrong. Very important, there were lots of accidents related to poor exhaust on turbocharged twin Cessnas.

Roughly speaking:

GTSIO-520 overhaul: $70K/1600 hours
Exhaust: $10K/1600 hours
Oil changes: $250/50 hours
Magneto work: $1500/500 hours
Top overhaul: $15K/1600 hours (one per TBO)
Fuel: 22 GPH block/hr, $5.50/gal

Total works out to $68/hour without fuel, $188/hour with fuel.

TPE331-10 overhaul: $225K/5000 hours
Exhaust: none
Oil changes: $400/900 hours
Fuel nozzles: $800/400 hours
HSI: $40K/5000 hours (one per TBO)
Fuel: 37 GPH block, $3.50/gal

Total works out to $55/hour without fuel, $185/hour with fuel.

Within the accuracy of this exercise, it is a tie. You can play with fuel prices, maintenance prices, etc, and make each engine come out a little ahead of the other, but at the end of the day, they just aren't that much different in $/hr.

Once you normalize for speed, the TPE331 engine costs less per mile than a GTSIO-520.

This doesn't put any value on the reliability difference, which is huge. Plus no misfueling accident, no threat of 100LL going away, 300 knots changes your life, etc...

This is the math that convinced me to look at MU2 numbers. The MU2 is the answer to the question "what is the most performance I can get for 421 money?".

Mike C.

Me too Jim.

Every time I open up the spreadsheets, I somehow expect the numbers to have gotten lower but they haven't. Then I go to the company bank account and expect the numbers to be much higher but they're not.

You're exactly right - gotta put some more cabbage in the funnel. No problem...

The geared Lycomings the factory orphaned decades ago. Still good parts availability because of all the GO-480's out there, but there will come a day. Also, the only guys sitting on parts (they bought Lycomings inventory) and specializing in overhauls charge you an arm and a a leg, because they know they have you over a barrell.

Are the geared Continentals still factory supported? Or is it a similar scenario where one seller sits on most of the parts?

You can buy a GTSIO-520 new from Continental today and can still get parts.

IIRC, there was a pinch on starter adapter viscous dampers a short while ago, but that was a supplier QC issue I believe.

Should be no near-term concern to operators, IMO.

Yes. You can buy a factory new one as well. They also stock many of them according to the inventory list on their website.

Steve,
Are you thinking about coming to the dark side of twin Cessnas? I love mine!!!

Apology accepted!

As others have pointed out, Continental does a great job of supporting these engines - Noting at all like the orphaned Lycoming.

You can purchase brand new GTSIO-520's from Continental and they will build them up in Mobile for you! Continental also offers factory remans and of course RAM will sell you an overhauled engine. There are a number of shops who will overhaul them for less $ as well.

The GTSIO is slightly more expensive to overhaul than the 520's that are on 340 & 414s - RAM shows $60k for a GTSIO-520 and $50k for a TSIO-520, so there's a $20k difference between a 414/340 and the 421 over the life of two engines just for overhaul costs. There are those who would argue that the difference is less because the GTSIO runs cooler and doesn't go through cylinders as fast, but that's likely offset by the starter adapter inspections.

Over 1600 hours, the $20k difference in engine overhaul costs is $12.5/hour. Worth it for me.

Robert

My research suggest this is true.

I'd rather have the GTSIO-520 than the TSIO-520. The TSIO-520 in the 340/414 feels like it is working quite a bit harder despite being lower power.

Mike C.

The cost of the 421C engines is precisely why I 1st looked for low time engines when I purchased mine.. Just look at controller and see the cost some of the owners are asking for the 421 with 200-400 hrs left till 1600.. Pretty crazy...... $140k in the engines....

I believe the new engines have a heavy case that has been designed to mitigate the case problems...

My 78 P210 has a useful load of 1370 pounds. It has tip tanks - so nearly 7 hours with no reserves. I work on 5 hours with reserves, which takes us 900 nm in nil wind. This gives us 620 pounds for passengers and baggage. Our family of 5 (3 boys, 8, 6, 3 yrs old) only weighs 480 pounds at this stage - so we can still take 140 pounds of bags. The 210 has been a wonderful travelling machine for our family - very frequently we all pile into it.

However I am very mindful of how quickly we are outgrowing the 210 - 3 boys grow before your eyes. Plus our 210 doesn't have any ice protection.

I always thought a 340 or baron would be our next plane - but like Cliff I am starting to think a 414 or 421 is what we need.

To compare to my 210 - how many pounds of people/baggage can a 421 carry going 900nm with 2 hours reserve?

Not that much different than a 340/414/P Barron though. In fact, RAM lists the PBarron engine at $54k vs $59k for the 421 engine.

For some reason many people think the GTSIO 520 is crazy expensive to overhaul. It's just not true... It's between $5 & $10k more expensive to overhaul a GTSIO-520 than a non-G TSIO520.

Robert

TSIO 520 cases definitely have cracking issues. Just replaced one w/ new that had been repaired 4 times before on the current reman (Western Skyways). Cost for the new case-5,600.