K versus J Maintenance Costs

[Seanhoya]

I am considering my next Mooney, and I wanted to ask if anyone has any thoughts on annual maintenance costs between non turbo-charged and turbo-charged Mooneys? I know the conventional wisdom - that turbo-charged Mooneys are more expensive to maintain, but does this hold true when put to the test of actually comparing numbers?

I spend $10,000 to $15,000 annually to maintain a 1968 G to my standard of maintenance. Does anyone have estimates for Js or Ks which might be data points for comparison?

[KLRDMD]

The K has two more cylinders than the J and a Continental versus a Lycoming. Jewell's pricing shows about a $9,000 premium to overhaul the K engine versus the J engine. If you don't run the K correctly you're looking at a set (or two) of cylinders during one TBO cycle. The K also has a turbocharger and potentially a variable waste gate and intercooler. The engine TBO is 1,800 hours on the K and 2,000 hours on the J.

Is the K more expensive to own and maintain than the J? Absolutely. How much more? That's too variable to put into hard numbers.

[jlunseth]

Does your 10-15k include an accrual of the cost of an overhaul or factory reman when the engine runs out? If not, then I would say you could maintain a K for well within your range if you buy well, meaning you don’t let yourself buy a bargain thinking you are going to be able to manage the maintenance. It just does not work that way. But if the aircraft has been reasonably well maintained you would be good.

Don’t forget, though, that most of the K fleet is going to have at best, early 2000s avionics like the 530/430s, and the APs are 35 years old. If it is an original King panel it is going to be all 80s technology. With at K you are going to fly hard IMC and in the ATC system alot, it pays to have good avionics and they are not cheap.

[carusoam]

Exhaust pipes, turbos, extra cylinders...

If properly run to last... the extra expense only comes at OH...

If run in flaming dragon mode... the OH on these parts is due at half time...

If you avoid flying in the FLs... go with the extra cylinders and avoid the turbo... 

Best regards,

-a-

[Ragsf15e]

It might be a little more, but angle valve J cylinders are expensive, so that’s a wash with the 6 cylinders on a K.  You’ll get wherever you’re going faster in a K so maybe less hours?

Cost difference will be negligible by aircraft ownership standards.

[larryb]

I owned my J for 5 years and 500 hours, and my K for 4 years and 400 hours. In my ownership I replaced a cylinder on each engine. So a wash there. I had to have the turbo scavenger pump rebuilt on the K. The J does not have such a pump. The K also has built-in O2 and I have spent some money maintaining that system. A turbo airplane often has more systems and therefore will cost a bit more to maintain them. But, overall it's pretty close. 

 

Larry

[Seanhoya]

4 hours ago, larryb said:

I owned my J for 5 years and 500 hours, and my K for 4 years and 400 hours. In my ownership I replaced a cylinder on each engine. So a wash there. I had to have the turbo scavenger pump rebuilt on the K. The J does not have such a pump. The K also has built-in O2 and I have spent some money maintaining that system. A turbo airplane often has more systems and therefore will cost a bit more to maintain them. But, overall it's pretty close. 

 

Larry

Larry - Do you see a significant speed advantage of the K over the J? I recognize that this has a lot to do with altitude. I have traditionally done most of my flying down low up to 8000', although I took a normally aspirated Mooney up to 11,500 and even 12,500 once out West. So it is hard to say whether I will do more flying in the FLs, because I have never really had a need to, in the past. But I do a lot of long-distance flying, so if the benefit is there, I might start flying higher. Thanks, Sean.

Edited April 11, 2021 by Seanhoya

[ArtVandelay]

I think Js useful load are generally higher than Ks if that’s important to you.

[jlunseth]

3 hours ago, Seanhoya said:

Larry - Do you see a significant speed advantage of the K over the J? I recognize that this has a lot to do with altitude. I have traditionally done most of my flying down low up to 8000', although I took a normally aspirated Mooney up to 11,500 and even 12,500 once out West. So it is hard to say whether I will do more flying in the FLs, because I have never really had a need to, in the past. But I do a lot of long-distance flying, so if the benefit is there, I might start flying higher. Thanks, Sean.

Its not simple. Take the example of a trip from FCM, where I am, to Denver. Typically the winds aloft will not be favorable on the outbound, so it will be best to stay down as low as possible. The two aircraft will be a tie on that leg, or the NA aircraft might have a slight speed advantage if you are really low. On the return leg, if you get into the high teens or flight levels you will not only pick up about 30 kts. just from the altitude, you will also pick up tailwinds. They can range anywhere from 30 kts. in the summer to 100+ kts. in the winter. You will have a cruise TAS of around 170 kts. or better, plus what the tailwinds give you. I have seen groundspeeds of more than 300 kts. on a couple of trips, 230 kts. is not at all uncommon. So for the entire trip, outbound and inbound, the K will have the advantage. 

But speed alone is not the big advantage of the turbo. I live in the midwest. We have lots of what I call popcorn cumulus all summer. It ranges from bottoms of 4-5 thousand up to tops of 16k. Under the cumulus is rough. In the cumulus is just as rough and it is IMC. If you are able to get above the tops then it will be sunny and glass smooth. You may pay a ground speed penalty, but it is well worth it to avoid soldiering through the cumulus at 6 or 8k. The turbo will not only have a speed advantage up there, but it will climb full power to that altitude and higher. 

[louisut]

In addition to getting above wx, there is hardly any traffic in the 12-18k range. It's too low for jets and too high for naturally aspirated planes. Depending on your region, this may give you significantly better routing when IFR. If you do a lot of long distance flying, I'd definitely go for the K.

[A64Pilot]

If you have a real need or use for a turbo, by all means get a turbo.

‘I live in Fl and may never go over any real mountains, and if I do the J model is perfectly happy at 15,000 or 16,000, maybe higher. It just takes time to get there, and once there it’s sort of a dog compared to a turbo,but if your only going there once or twice a year or less do you need a turbo?

Which is completely different of course for those that live at altitudes that I normally fly at, and have mountains nearby 

‘A lot of how much more does it cost has to do with your familiarity of a turbo and your desire to use it, but that I mean if you always fly at max boost, it’s going to cost you more, really similar to a NA motor, run a NA motor at 65% power or less all of the time except for climb and at TBO it’s likely all the expensive parts won’t need replacing.

I’d say plan on 20% more on motor costs, it may be less and if it is, then it’s a pleasant surprise.

‘If you don’t mind me asking, what are you spending $1,000 a month on? Flying a whole lot or upgrades? I would think a turbo Mooney could be flown quite a lot and maintained perpetually on $1,000 a month, but then I’m just maintaining old avionics and not replacing with glass either.

‘So I guess I’m saying maintaining, not improving 

Edited April 11, 2021 by A64Pilot

[aviatoreb]

1 hour ago, louisut said:

In addition to getting above wx, there is hardly any traffic in the 12-18k range. It's too low for jets and too high for naturally aspirated planes. Depending on your region, this may give you significantly better routing when IFR. If you do a lot of long distance flying, I'd definitely go for the K.

Yeah - that's my experience that always also factors into my planning - flying the eastern corridor region can be pretty busy but nonetheless as you say in the 12-18 range it is usually very quiet and peaceful.  Also I tend to get much more direct routing as a consequence.

[larryb]

Using Garmin Pilot logbook reporting feature, I had an average cross country speed of 133 kt in the J and 146 kt in the K. Average block-block times. I flew the J at generally 8.5 gph and 11 k. I fly the K at 9.5 gph at 11k for short trips and 17k for long trips.  If I want to speed up the K I can fly ROP at 14.5GPH and add 20kt. But MPG drops pretty significantly when I do that, so I don't do it often.

[ArtVandelay]

Speaking of maintenance and speed, before overhaul when I had a deteriorating cam:129, since overhaul 137 knots.

[aaronk25]

If a lot of your travel is by yourself popping from 12-16000 isn’t a big deal in the J. It’s slower than the turbo but it will do it. I have about 1300 hours in my J and have went from Phoenix to MN non stop (well almost, different story, but all over at 19000-21000.

 

When the turbo would be desirable is with pax with and wish I could have the HP to blow though 9000-10000 fasted to another air.

 

But, how often would you have pax with and want to deal with all the o2 masks? So for me a turbo would be nice at gross weights combined with higher altitudes and desired climb rates.

 

 

Sent from my iPhone using Tapatalk Pro

 

[A64Pilot]

You guys are really only getting 130ish kts true out of your J’s ?

[Eduleo]

32 minutes ago, A64Pilot said:

You guys are really only getting 130ish kts true out of your J’s ?

I thought those were ground speeds. Since I seem to always have a headwind, mine are probably even slower.

[ArtVandelay]

I thought those were ground speeds. Since I seem to always have a headwind, mine are probably even slower.

Yes, ground speeds.

Two things to remember,

1) when the wind is 90° to your course, you’ll need to turn into the wind to maintain your course. Even if the wind is 100° or more, it will actually slow you down if strong enough.

2) You’ll spend more time flying into the wind than you spend flying with it, so average over time will be lower. I don’t know how GP calculates it.

[EricJ]

8 hours ago, louisut said:

In addition to getting above wx, there is hardly any traffic in the 12-18k range. It's too low for jets and too high for naturally aspirated planes. Depending on your region, this may give you significantly better routing when IFR. If you do a lot of long distance flying, I'd definitely go for the K.

I cruise 12-14k pretty routinely in my naturally-aspirated J, sometimes higher, usually to avoid terrain.   I've been up to 17,500 with it with no significant issues.   I could have easily gone higher but I was VFR at the time.

[aviatoreb]

19 minutes ago, EricJ said:

I cruise 12-14k pretty routinely in my naturally-aspirated J, sometimes higher, usually to avoid terrain.   I've been up to 17,500 with it with no significant issues.   I could have easily gone higher but I was VFR at the time.

Climb rate too if 17.5 is to be a useful altitude.  I once timed a climb to 17 in under 13 min.

[EricJ]

Just now, aviatoreb said:

Climb rate too if 17.5 is to be a useful altitude.  I once timed a climb to 17 in under 13 min.

Admittedly I was getting a little help from a mountain wave at the time. 

I've found climb rates in the J up through about 15k to be not too bad, certainly not bad enough to make me wish I had a turbo.

[201Steve]

I need to get an oxygen rig it sounds like; with you other J’s rippin on up there. All other factors aside, the bumpy air in the hot southeast would be nice to regularly avoid. If not for my own sake, the passengers going for the puke bag. 

[Ethan]

The best part of the turbo K model is the amazing ability to climb out of icing and get into smooth air. I hate the pucker factor of climbing 300 fpm at 15k just to get out of the whispy cloud tops where lots of the ice accretes.

[WilliamR]

Attached is the model I built to capture all costs except upgrades for my 252.  15 years (1600 hours) of information summarized on the Ops Cost Summary sheet.  Note, I do my own oil changes and minor work as allowed by the CFRs.  Cost of parts but not labor are included in those cases.  I also do not include costs associated with detailing/washing the plane.  I do not abuse the engine and stay out of the red box but have had to replace cylinders (happy to show anyone 15 years of JPI downloads). 

I do keep the plane maintained to high standards as I work to maintain 100% dispatch reliability.  So, I'm sure my costs are somewhat on the high side.

Hope this helps.

William

AircraftStatusSheet 12-27-20.xlsx

[Ragsf15e]

1 hour ago, WilliamR said:

Attached is the model I built to capture all costs except upgrades for my 252.  15 years (1600 hours) of information summarized on the Ops Cost Summary sheet.  Note, I do my own oil changes and minor work as allowed by the CFRs.  Cost of parts but not labor are included in those cases.  I also do not include costs associated with detailing/washing the plane.  I do not abuse the engine and stay out of the red box but have had to replace cylinders (happy to show anyone 15 years of JPI downloads). 

I do keep the plane maintained to high standards as I work to maintain 100% dispatch reliability.  So, I'm sure my costs are somewhat on the high side.

Hope this helps.

William

AircraftStatusSheet 12-27-20.xlsx 167.72 kB · 6 downloads

Never ever share that with my wife.