421C cruise is 210 KTAS on 45 GPH. Fuel price average $4.50?
MU2 cruise is 300 knots on 70 GPH. Fuel price average around $3.50.

Works out to $0.96 per nm for the 421C, $0.82 for the MU2.

Cheaper fuel cost per mile for the turboprop.


For owner flown, 100 hours/year, effectively the same thing.

Not been a big deal. The programs often have less to do every year than a full annual.


Nonsense.

421C GSTIO-520N is about $75K to overhaul, about $15K for exhaust overhaul, about $15K for a mid life top, over a 1600 hour TBO. About $65/hour, $0.31 per nm.

MU2 TPE331-10AV is about $225K to overhaul, about $35K for hot section, nothing else to do, over a 5000 hour TBO. About $52/hour, $0.17 per nm.

If we include routine maintenance (mags, plugs, oil changes, exhaust inspections, etc), the comparison gets worse for the piston since there is almost nothing to do to the turboprop engine routinely.

Cheaper engine cost per hour and per mile for the turboprop.


What are you smoking?

On my worst headwind day, I am making ground speeds of a 421 with zero wind. There is no day ever when the 421 is faster than I am (even allowing for the 421 to fly much lower) and plenty of days I am 50% faster than it is, particularly in a headwind.

Mike C.

Zeke, what are the real costs of a 421? If we're being honest and not fudging numbers as you said.

What's the actual, real, installed cost of a an engine overhaul on those? I bet you don't get any change on $80K/side. For 1600hr TBO (which we all know will have to have top end work before that). $80K/1600hrs = $50/hr. TPE331 is $250K for 5400hrs = $46/hr.

Just oil changes on any piston twin, unless you do it yourself, is $500/50hr. That's $16K over the engine life of a 421. That's about what a low end hot section costs.

On a 414A, about $140,000, 421C will be closer to $180,000 for a complete firewall forward overhaul and install if you're not shopping around and want to be in and out in a respectable amount of time. Add another $30K to $40K during next 1600 per set of engines for maintenance, parts and pieces.

Just to compare to the small King Air (C90).
On trips, we fly in the low flight levels that goes a bit slower but reduces fuel flow.
Normally cruise around 225 to 230 knots. Six hour range there with average burn of 70 GPH. Full fuel payload on our bird is near 900 pounds.
The C90 isn't the fastest, but is a roomy SUV with eight seats, coffee pot, potty and other comforts. It's also a very forgiving aircraft with great cross wind manners. Part 91 folks can find older used birds in descent shape for under $500,000 if willing to fly past TBO there are bargains. Annual maintenance runs between $40 and 60 thousand a year.

Respectfully, the numbers I used are close and you aren't providing any numbers yourself.

A 421C will cruise about 210 KTAS and burn about 45 GPH doing it in cruise. LOP numbers will be slower and lower fuel flow (but then, I can throttle back the turboprop similarly).


I fly about 25,000 to 40,000 nm per year. My long running average is about $750/hour including fuel, maintenance, hangar, insurance, misc.

MPG: in my typical economy cruise, FL280, 65 GPH, 290 knots, that is 4.46 nm/gal. 421C is 4.67 nm/gal, but at higher fuel cost.

One thing to keep in mind is that you fly more hours in headwind than tailwinds. This is not only due to slower ground speed, but also due to tailwinds being additive on less than 180 degrees of your possible course. The slower airplane cuts through headwinds less well, so the speed difference is more significant than it first appears. Thus my advantage is actually increased in actual service.

I pay $8,275/year in insurance. $4,275 for full hull coverage ($450K hull value), $4,000 for liability, $5M smooth. I don't have recent 421C figures, but suspect it would be the same or higher for same hull value. Not clear underwriters would consider $5M liability coverage on a 421C.

Maintenance has been anywhere from $12K to $38K per year, averaging around $20K. This year was the worst year ever, did prop overhauls ($14K for a pair).

Apples to apples, I am flying my MU2 for what a 421C would cost, if not less, for the same mission mix. That doesn't count the greatly improved speed, climb, reliability, and safety of the turboprop.


Prices I can get in Texas, for example:

KGOP: $2.19
KACT: $2.23
KDTO: $2.53
E52: $2.59
0F2: $2.62
KCPT: $2.64
T35: $2.68
T90: $2.70
66R: $2.80
KELA: $2.80
2F5: $2.80
KGGG: $2.80
F41: $2.85
KHOU: $2.88
KCOM: $2.94

They are dozens more under $3.30/gallon and they are mostly full service.

Jet fuel is significantly cheaper than 100LL overall. Jet fuel list prices are misleading, very rarely do I pay that anywhere due to contract fuel. My long term running average for jet fuel is around $3.30 or so. Thus the best you can do is about my average.

Mike C.

I really have nothing significant to add but,

I have been amazed watching some friends of mine operate a straight CJ for the last few years. They are flying 300+ hours per year and almost never have to do anything to the plane other than tires and brakes, everything just works. They are on both the parts and engine programs, but honestly I don’t know why. When you really look at the numbers for this level of flying it’s hard to see how anything could be more efficient. It also appears that these ~1M$ range CJ’s experience almost no depreciation currently.

I just think if you are in the market to spend 600-800k on a turboprop then you owe it to yourself to look closely at the CJ.

I have operated a 421B. I'd say those number are close. Maybe more like 40-42GPH for 210 kts.

Citation 500SP seems cheap here as well...
How much do they cost to operate?

This is true. I have experience.

I have been to the last 3 MU-2 PROP seminars. I talked with 10 to 15 operators at each event. Almost all report $1,000 an hour or more operaring cost. Mike is the only one I have seen report under $950 an hour. Even so, the MU-2 seems to be one of the least expensive twin turboprops to operate. One additional cost that Mike does not have is the engine program.

Vince

No such things as a Citation 500SP.

There is a Citation 500 which needs 2 crew or if properly equipped SP with a single pilot wavier.

There is a Citation 501 which can be flown 2 crew or SP with the appropriate type rating.

My operating costs are darn close to Mike’s for an mu2

I've seen numbers around $1000 - 1200 / hr.

Like anything else there's lots of "depends".

Mike bought a plane with a lot of calendar maintenance just done that was also a cost-efficient airframe (short body/3 blade prop). He does a lot of the minor stuff (100/200 hrs) by a local A&P and not a big name shop (with accompanying ferry costs) and seems to be particularly fastidious about avoiding fees and pricey fuel. These conditions are simultaneously real, reasonable and rare.

He also doesn't include engine reserve in the DOC - argument being that it's really a depreciation issue that in most cases is only assessed (subject to market vagaries) at resale.
Not sure how to apples and apples compare that to a 421 - You can make the argument that 700 hrs on a TPE-331 (say from 1400 to 2100 SMOH) may not make a big deal in an MU2 resale. It certainly will in a 421. Probably a real airframe/market difference that favors MU2.

And my daughter wants an emoji added