Questions about the 231/252 K models

[Doggtyred]

Howdy gang. 
New guy to this forum. First post is to ask a question of the K model owners about the operating costs for their birds... I am getting back into flying after a hiatus, and once I'm current again I am looking at something that can make the trip from Houston to the East coast a little more practical, which is where I've settled on the Mooney and most particularly the K models as what I would be interested in... Mission is wife and I going places, to see family, explore the country.. Occasionally 4 pax doing local stuff, but mostly 2 seats, full fuel and some bags going for long hops. 

I am trying to get an educated estimate on what others budget for their operating costs and was hoping some of you might share. A little about me: 450 hr PP, will have IR before purchasing anything, Roughly 130 hrs retract, split amongst A36, Pa200R, C177RG, C182RG and M20E. 125 at night, 250 XC. 

Looking at what you use for cruise settings: power, MP/RPM, altitude, fuel flow...Do you go high enough to need oxygen or keep to 12k or lower?
What sort of costs do you budget for: average problem free annual, engine reserve, other hourly reserves....
Locally maintained? or do you use a specialty shop? Recommendations for engine rebuild?
Any mods to avoid? Any mods you'd recommend

Looking forward to reading up on this forum.... 

[carusoam]

Welcome aboard DoggT.

Nicely detailed first post.

Why the preference for a TC'd engine? 

The ultimate traveling Moonies are TC'd and TN'd.   The annual costs creep up in expense with each system that gets added.  

Flying comfortably without using O2 systems is pretty good too.

Enjoy the hunt!

Best regards,

-a-

[DonMuncy]

Just to answer one of your questions. If you plan on staying under 12,000, you don't want a K. Under about 8, a J will outperform a K at a lower fuel burn. At 10 - 12,000 the K begins to shine. So, yes, if you have a K, you need to have Oxygen.

Just my opinion.

[Doggtyred]

I want to be able to have the ability to get above SOME weather, to be able to cruise climb reasonably quickly, to be able to keep sea level power up to cruise altitude, and to have the higher true air speeds. I'm ok with oxygen. Most of the ones I'm seeing listed for sale have factory 02. After a long XC at 10-12k in an A36 years ago I was pretty wiped out. I'm sure some of that was hypoxia.. this was before pulse ox's were as cheap and plentiful as they are now.

Mountains aren't in my immediate future but I would have the occasional reason to head to SLC or Reno so the capability of up and over would be a plus. But most of my intended flights would be from Texas coastal region to Boston area, Charleston SC area, Destin, Key West, Bahamas, etc. Been kicking around potential plans/routes on the computer and looking at times and guestimated fuel burns and operating costs and wanted to talk to the folks who have the plane I THiNK I want... 


 

Edited August 16, 2016 by Doggtyred

[GeorgePerry]

You might also want to consider an IO-550 equipped mooney.  Missile, Eagle, or Ovation.  You'll get much better speed than a 231 down low and as good up to O2 required altitudes.  Oh and none of the maintenance headaches associated with forced induction.

[carusoam]

The TC is nice for flying in the FLs.  Some pilots around here will catch tail winds in the high teens regularly.  Crossing a Great Lake and staying within gliding distance to the shore gets straighter with altitude.

my preference is fast, efficient, and below 12,500'.  The IO550 does this really well. 175 kts ROP, 165 kts LOP....

Using the turbo is a great way to gain efficiency, but it only occurs in thin air. The turbo produces SL power while the airframe experiences 18k' of air drag...(generally).  There can be cooling challenges regarding SL power.

Flying a turbo at 12k' kinda of adds complexity without getting the gains.  Pretty much the reason that many of the TC'd Mooneys have the built in O₂ system....

Find the thread of pilots discussing Mooney TC operations including LOP at altitude.  They are some of the most interesting discussions on engine OPs in the Mooney world.  If you like engines this much, discussing MP controllers, inter coolers and TIT is for you! 

TN'd planes also have some interesting attributes that may be of interest while you are looking...

Best regards,

-a-

[peevee]

I like to cruise high. If the leg is long enough to justify it I go 170, 180 or 190 pretty much every flight, but I also cross the Rockies almost every flight and the mvas are 14 to 16k

 

If our plane had tks it would be perfect. 

Edited August 16, 2016 by peevee

[FBCK]

Here is a great thread on the 231 engine management with lots of good information that will save your 231 engine.

 

 

[dlthig]

3 hours ago, GeorgePerry said:

You might also want to consider an IO-550 equipped mooney.  Missile, Eagle, or Ovation.  You'll get much better speed than a 231 down low and as good up to O2 required altitudes.  Oh and non of the maintenance headaches associated with forced induction.

I completely agree with George. However, and there is always a however, M, E and O actually spells MORE as in MORE MONEY. I have a similar mission and desires and just can't justify a 150-175K for a toy. I'm not smart enough to get anyone else to pay for it for me, so writing it off as a business expense isn't likely.

[milotron]

I am an new-ish owner of a M20K with the 252 upgrade about 50 hours since April. Fantastically capable aircraft, especially with the TKS and 02.  Great for getting over the rockies or over weather.  The 252 with the MB engine is not much more difficult than normally aspirated ( in fact easier as MAP doesn't really change from where you set it ) with the intercooler and pressure controller. Keep an eye on leaning and TIT, but it isn't really a big deal keeping things under control. I came from Cessnas and a DA40 and the biggest learning curve was speed management on an approach, but speed brakes help with lack of planning.

[carusoam]

Timeline and horizon help make these things affordable...

My first plane needed to be bought with cash. Expecting it could fail miserably.  As simple as flying didn't work out as expected for the family...

Once you can see flying being part of your life out into the future, it is easier to make payments on something that can last for decades.

The same payment can buy a C or an R.  The R will just have more payments.  Interest rates are as low as they are ever going to be.

A nice 252 is in the long horizon category like any of the LBs...

Best regards,

-a-

[Zwaustin]

Welcome aboard. As others have said take a good look at your type of mission but for what it's worth I have a 231 with intercooler and couldn't be happier. Fly frequent trips from Austin to Arizona at 15k-19k but I fly where best winds are so will go lower. Due to usual above std temps where I live power settings are around 25-27/2500 at those altitudes for 70 percent power. Usually burn around 10gph LOP, about 12ish ROP but can burn less if you throttle back. 

Most of my maintenance is done locally at home base but I took it to Don Maxwell this year for annual to get a MSC set of eyes. 40 bucks dry covers my engine overhaul and prop overhaul along with some maintenance. I would gladly send you a full cost spreadsheet if you would like that breaks everything down, just send me your email. Good luck in your search. 231 and 252 are great planes for the money in my opinion. 

[Doggtyred]

1 hour ago, Zwaustin said:

Welcome aboard. As others have said take a good look at your type of mission but for what it's worth I have a 231 with intercooler and couldn't be happier. Fly frequent trips from Austin to Arizona at 15k-19k but I fly where best winds are so will go lower. Due to usual above std temps where I live power settings are around 25-27/2500 at those altitudes for 70 percent power. Usually burn around 10gph LOP, about 12ish ROP but can burn less if you throttle back. 

Most of my maintenance is done locally at home base but I took it to Don Maxwell this year for annual to get a MSC set of eyes. 40 bucks dry covers my engine overhaul and prop overhaul along with some maintenance. I would gladly send you a full cost spreadsheet if you would like that breaks everything down, just send me your email. Good luck in your search. 231 and 252 are great planes for the money in my opinion. 

PM sent.. thank you... 

[Ron McBride]

What is the effect of density altitude on takeoff with a turbo plane.  I know that my F, the takeoff gets a lot longer with density altitude.   I aborted a takeoff a couple of weeks ago, I made a plan, and the plane did not perform. I spent the night, and left at 8 am the next morning exactly as my plan was.

Landing distance's should be about the same for a F, J or K at the same weights.

Ron

[carusoam]

A few things come to mind...

1) less density = less thrust + less lift

2) requires longer time to get up to speed, higher ground speed to get the usual airspeed.

3) higher AOA to generate the lift required.  More AOA is additional drag.

The TC solves one of the technical challenges.  Making power.  The other challenges are airframe ones and don't go away without a lot more power.

As usual, these are PP discussion points.  I am not a CFI...

Best regards,

-a-

[kortopates]

A few things come to mind...

1) less density = less thrust + less lift

2) requires longer time to get up to speed, higher ground speed to get the usual airspeed.

3) higher AOA to generate the lift required.  More AOA is additional drag.

The TC solves one of the technical challenges.  Making power.  The other challenges are airframe ones and don't go away without a lot more power.

As usual, these are PP discussion points.  I am not a CFI...

Best regards,

-a-

Really it's all about Anthony's #2 - the only real effect is that it will seem like it takes forever to accelerate to rotation speed as a lot more runway goes by and once airborne it will seem like a long time to accelerate to Vy - because it is. But the difference is entirely because the higher the DA the more TAS becomes greater than IAS. The airplane pretty much performs identically at any altitude at the same IAS - it obviously just takes a lot longer to get up to a faster TAS. #1 is actually a plus and why a TC aircraft will go ~2 Kts TAS faster for every 1000' DA increase in altitude with the same power (IAS will be the same) which is why us turbo guys don't like to stay low and share the crowded sub-teen airspace with the likes of the NA crowds that have no clue on what they're missing out on. The inexperienced NA pilot will suggest a turbo only becomes useful with a tailwind - typically going east. Although there is some truth to that, the reality is more often the NA pilot will be flying lower under, in or between layers with the weather and turbulence while the turbo pilot will find smooth sunny VMC conditions on top of it all. What about those fierce head winds? They're there alright, but rarely does the head wind component go up with altitude uniformly and faster than the 2kts per 1000' we gain in TAS meaning that by closely looking at the winds aloft you'll find an altitude that minimizes the headwind component and very rarely is it less than 10K out west were I fly. (Good flight planning apps take this into account for us). But even when it's is, I'll gladly take a few minutes penalty to climb to smooth sunny VMC air than cruise in the bumps to save some time. After all, the bumps rob you of a significant amount of airspeed anyway.

Read the other thread of the K owner that just bought the 231 and flew his first x-xctry trip from Ohio to the west coast - he sure gets the utility now as you will hopefully too.

Lastly I highly recommend you skip the 231's and go for the 252's or MB modified 231 (e.g. 262 mod) if you can afford it. With the MB you get a true complete turbo with a hydraulic controller that is often referred to as the "set and forget controller" which makes its an entirely different engine with numerous advantages discussed at length elsewhere. But they're rare and hence why we have many more 231 pilots on these pages that will argue they'll get much of the same performance with a highly mod'd 231 - there is a lot of truth to that but the MB is vastly simpler to operate and much better adapted to flying in the flight levels. If useful load is a concern; go for the 252 encore conversion or encore.

Sent from my iPhone using Tapatalk

[GeorgePerry]

You don't have to fly a Turbo to go high. I take my eagle up to FL180 regularly esp if winds make the climb worth while. In the high teens there's nobody to share that airspace with and getting direct is a no brainier. When winds are bad an NA ALSO gives you performance down low at 4-10k feet.

also from a safety standpoint flying an unpressurized airplane much above FL180 presents a set of risks that have to be closely monitored  and managed. Hypoxia is a real concern. time of useful conciousness goes down significantly above FL200.

Run a search on flight aware. The vast majority of turbos are actually flown at 12k and below, likely to avoid having to put on O2 which I think we can all agree is a PITA and non pilot passengers have very little tolerance for wearing canulas.

all this isn't to say a turbo is a bad option. The 252 w a MB engine is one heck of a great plane, esp if you live in a high altitude area like Colorado. but there's no arguing with the fact that to get the most out of a turbo mooney you have to go high and have rubber tubes up your nose 

 

[Doggtyred]

Thank you for the folks who were able to answer the specifics for the questions I had.  The LOP thread was particularly interesting. I read Deakin's articles as they came out in Avweb many years ago, and found them very useful. 

And thank you to ZW for the spreadsheets.. the cost per mile and cost per hour breakdown gave me an idea of what I'd be getting into. 
 

[peevee]

10 hours ago, GeorgePerry said:

You don't have to fly a Turbo to go high. I take my eagle up to FL180 regularly esp if winds make the climb worth while. In the high teens there's nobody to share that airspace with and getting direct is a no brainier. When winds are bad an NA ALSO gives you performance down low at 4-10k feet.

 

A lot of airplanes can get to 180. The point of the turbo is the rate at which you climb to 180 and your tas at altitude. I'd imagine the climb time and airspeed make it not worthwhile too often. 

[GeorgePerry]

5 minutes ago, peevee said:

A lot of airplanes can get to 180. The point of the turbo is the rate at which you climb to 180 and your tas at altitude. I'd imagine the climb time and airspeed make it not worthwhile too often. 

All this discussion is academic.  The point of all this was to offer a different perspective to Doggtyred and I respectfully disagree with your opinion that TTC and TAS don't make the trip up to FL180 worth it for a NA big bore.

With 310 sea level hp on tap, time to climb and TAS at FL180 is still quite respectable.  From a TTC perspective, its a tortoise and hair deal.  From SL to 10K a 310 hp Eagle/Ovation will out climb any mooney 231/252.  After that the turbo starts to catch up...The last 8k of the climb the turbo might pull ahead by a small margin but it isn't significant.  It would be interested to compare TTC and distance covered #'s of a 310 HP Eagle/Ovation and 231/252 to FL180 along with TAS in normal cruise.  

The "a-ha moment" for those not familiar with the various model choices is that Turbo's are good planes...but they have to be operated in certain areas of the envelope to get the most out of them.  Turbo's are good for High DA runway operations and in cruise are good in one corner of the envelope (high, often times headed east and require rubber O2 hoses up the pilots noses:-).  231/252 with only 210 hp makes take off performance lackluster and come with some significant maintenance costs needed to keep the forced induction systems happy...not to mention the probability of a TOH nearly being a requirement about every 1000 hours.

Big Bore NA Mooney's are good across the spectrum....Power to get off the ground quickly with short TO roll compared to a turbo.  They are fast down low, fast enough up high and TTC is better in a 310 NA if we use 12K as the finish line.  And that's how most turbos are flown, at 10-12K.  Just check out Flight Aware...Most M20T's are flown in the mask-off-is-phere. http://flightaware.com/live/aircrafttype/M20T

Anytime you're up for a race, let me know 

[gsxrpilot]

As a new owner of a 252, I gotta say I'm very happy with it.  I decided early on in my search, that the 231 was off the table. My previous plane was a C and while I loved it, every time I flew it, I wished it was an E. I didn't want to have a 231, wishing it was a 252 every time I flew.

I looked at the Ovation and the Eagle, but everything is about compromises and the 252 was the right combination of lower cost, high altitude capability, long range, and a variety of them for sale to compare.

I can't help with costs of ownership yet as I'm only about 10 hours into it.  But I'm happy to talk about my search and decision process.

[jackn]

To state the obvious, getting there and home safely without getting stuck is the most important thing. Of all the airplanes I looked into, the Encore was the best for the money. Dual vacuum, dual alternators, long rang tanks and TKS anti-ice as a bonus. Three of these have Allowed me to complete my journey at one time or another. Remember Murphy and his law? I had an alternator fail at 6pm on the Friday before a 4th of July long weekend when I was heading home. 5-10 kts isn't going to make any difference. I run at those speeds. FWIW below is my engine monitor. You can see the fuel burn ROP at 75% and LOP at the same settings, but now at 65%. TAS in not important as that will change depending on altitude and the conditions of the day. 

[dlthig]

Nice comparison Jack. A gallon per knot ain't worth it.

 

 

[GeorgePerry]

175 TAS 11.8 GPH at 11,000 +10 ISA & a 1130 lb useful load.  Systems redundancy is nice but with all those TKS panels (which are not FIKI approved), extra vacuum pumps and alternators, the 231/252 can't come close.  Like everything else in aviation mission priorities result in trade offs...to each his (or her) own.  

 

[peevee]

8 hours ago, GeorgePerry said:

 

Anytime you're up for a race, let me know 

Sure. Come on up to Colorado mid summer and we'll see, Glenwood springs might be fun on a hot day. 

At fl180 you have probably 155hp. I still have 210....