Light Twin Owning and Operating Costs

GRG55

GRG55

Final Approach
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Aztec Flyer
On another thread MotoFlier indicated he would be interested if I might post the actual operating cost data for my twin, in a similar fashion to Eggman's earlier thread about his 310 cost data. I am new to this forum so not sure if there is already another thread where this should have been added, but presuming not perhaps over time others flying various types of twin engine aircraft might add info here to allow comparisons for anybody operating a twin or thinking about buying one?

I keep a spreadsheet with every cost since making the offer to purchase the plane, and have segregated into roughly the same categories as Eggman's 310 cost post.

Airplane is a 1979 Piper Aztec 'F' with naturally aspirated IO-540 Lycomings; approximately 5500 TT and 1300 on the engines. The data below covers the period from October 2012 until year-end 2015 (~3 years); the costs are cumulative (divide everything by 3 if you want average annual costs) and I have included some clarifying notes in some categories.

Hours flown: 311

Pre-buy inspection: $2844 (included 1 hour flight to ferry airplane and function test avionics, instruments, autopilot operation)

Purchase & registration taxes and fees: $5060

One time equipment and outfitting: $7264 (includes portable O2 system/accessories, tug, 28v battery maintainer, some tools, etc.)

Replacement overhauled propeller (RH): $8078 (a year into ownership one electric de-ice cuff failed and I pulled the prop to have them replaced, discovered some prior prop shop had stamped numbers into the hub in a way that made it non-airworthy and not repairable - faster to locate a complete prop instead of trying to find a hub only. Pulled other prop but it was okay. Cost above includes overhauled prop purchased, freight, freight insurance, inspection by my local prop shop on arrival, installation of new electric de-ice cuffs and labour to install on the airplane. Stuff happens :mad2:)

Lower cowl modification STC: $700 (for anyone not familiar with the Aztec cowls they are a complete nightmare to remove and reinstall, especially the lower cowl which requires one fuss with 9 small machine bolts (each side) up in the main wheel wells, removing all the nacelle to wing fairings and disconnecting the cowl flap linkages. Hours of fun and games (and non-family friendly utterances). This STC mod, for non-turbo Aztecs, splits the lower cowl ahead of the air intake dispensing with all the items listed above. Removing or reinstalling all the engine cowls is now a 15 minute per side operation by one person. Arguably the best money I have spent on this airplane.

Landing and parking fees: $805 (parking at Reno during the air races in 2015 accounts for $285 of that).

Consumables $2502 (oil, various filters)

Parts and materials: $6418 (includes replacing brake rotors and pads, new ignition harness, new exterior fasteners, complete set new spark plugs, new starter RH engine, parts for servicing all 4 mags, etc)

Maintenance labour including annuals: $8144 (my mechanic has an official written policy refusing to deal with Aztec cowls, so I do all that sort of stuff to keep costs down :) )

Insurance: $6350 (includes in-motion hull)

Hangar: $12,800

Fuel: $38,502 (I typically cruise @ 2250 RPM, slightly ROP, running 11 gph indicated per side, actual total measured fuel including taxi and climb normalizes around 28 gph +/- 0.5 gph depending on the length of trip and altitude. Time going direct point-to-point is more important to me than diverting to find cheaper fuel at out-of-the-way airports, so someone running LOP and actively managing their flight planning based on comparative fuel costs will do somewhat better than these figures.)

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One time total = $23,946 or $77/hour

Recurring including fuel = 75,521 or $243/hour (excluding engine or prop allowance)
 
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I have a PA-30 Twin Comanche. Her operating costs are more comparable to a big single as she has two little engines (160 hp) rather than one big one. Fast cruise at 7,000 MSL gets me 170 KTAS burning 18 gph. Economy at 12,000 is about 158 KTAS burning 13 gph. The way I fly, I average about 15 gph.

Hourly costs:

Fuel -- $65
Oil -- $2
Maintenance -- $60 (est. as I do my own maintenance so this is average shop costs)
Engine reserve -- $25
Prop reserve -- $5
 
Kristin said:
I have a PA-30 Twin Comanche. Her operating costs are more comparable to a big single as she has two little engines (160 hp) rather than one big one. Fast cruise at 7,000 MSL gets me 170 KTAS burning 18 gph. Economy at 12,000 is about 158 KTAS burning 13 gph. The way I fly, I average about 15 gph.

Hourly costs:

Fuel -- $65
Oil -- $2
Maintenance -- $60 (est. as I do my own maintenance so this is average shop costs)
Engine reserve -- $25
Prop reserve -- $5
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Insurance, Hangar, taxes?
 
Nice thread. I keep wanting to purchase my "last plane" and a light twin seems like a great way to really maximize my commitment to airplane ownership (which is a nice way to say that it will absorb all available funds). I don't think I can swing a Baron, so I've been looking at twins with smaller engines like the Travel Air. Thanks for the info.
 
GRG55 said:
Insurance: $6350 (includes in-motion hull)



Hangar: $12,800
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These two numbers seem incredibly high for an Aztec.

Where are you based and what is your hull value and ME time?

FWIW, that insurance number is double what I pay for a Baron with $120k hull value, although I did have over 150 hrs ME when I bought my airplane.
 
Challenged said:
Nice thread. I keep wanting to purchase my "last plane" and a light twin seems like a great way to really maximize my commitment to airplane ownership (which is a nice way to say that it will absorb all available funds). I don't think I can swing a Baron, so I've been looking at twins with smaller engines like the Travel Air. Thanks for the info.
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Paraphrasing the late Gordon Baxter "The cost of flying today is exactly the same as it was 50 years ago...all you got..."

I spent about a year researching various twin engine airplanes before making my decision. The smaller engine twins have a lot of appeal from a variable operating cost standpoint, but consider that your fixed costs of ownership will be the same, and it seemed to me airplanes like Travel Airs and Seminoles were in high demand and not priced that much below a more capable twin like an Aztec or even some short fuselage Barons.

The twin Comanche with the 200 hp upgraded engines would have been a great option, except I wanted FIKI if I was going to regularly fly IFR where I live.
 
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Is the discrepancy because it's for three years? That would be $6383/yr. That's still twice what I pay for my hangaring and insuring my Sierra. The hangar is dependent upon location, but I don't guess the insurance swings too much across the country.
 
Challenged said:
but I don't guess the insurance swings too much across the country.
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I don't think it does. As someone who has moved around with the military, unlike car insurance, I have found no noticeable difference in insurance premiums between locations.

Seems that with aircraft insurance, the biggest factors are 1) hull value, and 2) pilot experience.
 
Fearless Tower said:
These two numbers seem incredibly high for an Aztec.

Where are you based and what is your hull value and ME time?

FWIW, that insurance number is double what I pay for a Baron with $120k hull value, although I did have over 150 hrs ME when I bought my airplane.
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That is the insurance total for 3 years cumulative (divide by 3 to get the annual average). First twin for me, no ME time other than training before purchase, hull value is $100k, $2 mill liability. For the first year there was a bit of a discount because it was the second airplane on the policy with the Bonanza.

Hangars are overpriced at my airport, and rents were high because of the oil boom. Now that has busted we might see some sanity return. Certainly I am seeing some expensive local aluminum being put up for sale these days. Also, the Aztec won't fit into any of the cheaper T-hangars on the field, so I rent a steel hangar, insulated, heated concrete floor with running water. I just put up the numbers as they are in my historical records; obviously anybody using the figures for research needs to adjust them for their own local circumstances and things like hangar costs are going to vary considerably between major cities and more rural areas across the country.
 
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GRG55 said:
That is the insurance total for 3 years cumulative (divide by 3 to get the annual average). First twin for me, no ME time other than training before purchase, hull value is $100k, $2 mill liability. For the first year there was a bit of a discount because it was the second airplane on the policy with the Bonanza.



Hangars are overpriced at my airport, and rents were high because of the oil boom. Now that has busted we might see some sanity return. Certainly I am seeing some expensive local aluminum being put up for sale these days. I just put up the numbers as they are in my historical records; obviously anybody using the figures for research needs to adjust them for their own local circumstances and things like hangar costs are going to vary considerably between major cities and more rural areas across the country.
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That's not bad for insurance then.

Is the hangar cost for three years as well?
 
Fearless Tower said:
That's not bad for insurance then.

Is the hangar cost for three years as well?
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Yes, all the costs I listed are cumulative for 3 years (actually 39 months from October 2012 to year end 2015).
 
Fearless Tower said:
That makes a lot more sense. I missed the 3 year part.
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Sorry, I should have been more clear about that in the opening paragraphs of original post. I will go back and edit that to highlight.

I found tracking cumulative costs against cumulative hours more useful than trying to deal with wide fluctuations in both costs and flying hours between individual calendar years. Keeping a running total and ratio seems to give me a better picture of the true "full cycle" cost of the airplane...although why any of us want to know what it really costs to feed this obsession is beyond me.
 
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Fearless Tower said:
I don't think it does. As someone who has moved around with the military, unlike car insurance, I have found no noticeable difference in insurance premiums between locations.

Seems that with aircraft insurance, the biggest factors are 1) hull value, and 2) pilot experience.
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If you keep the airplane south of I-10 around Florida and the gulf states it use to be you would see an increase. Not sure if that still applies anymore or not.
 
Had a twin beech Travelair for over five years,paid for it as I went,put over eight hundred hours on it. Did not keep any figures,on operating costs. Figured I might not be able to justify the cost. Now I have a two seater,single engine,and still don't keep track of costs
 
I've never bothered to add everything up, but I use the $275-300/hour number for light twins of the Aztec/310/Baron category. It seems like my guess is pretty close to what those who have added it up have come up with.

Anyone done something similar for a Navajo?
 
The numbers are inline with what I'm planning for. Insurance was a little lower and hanger was higher so it balances out. Thank you for posting, it is a great sanity check for me as in I'm nuts for not running while I still can :rofl:
 
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MotoFlier said:
The numbers are inline with what I'm planning for. Insurance was a little lower and hanger was higher so it balances out. Thank you for posting, it is a great sanity check for me as in I'm nuts for not running while I still can :rofl:
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In my case I place the blame squarely on Cessna and their $15 Introductory Flight in a 100 hp 150 (yes, I know that dates me). I was hooked by 100 ft AGL on the first climb out. Good thing, because we then struggled for altitude from that point on. Wasn't smart enough to run then, too late now... :D

Seriously, PM me if you have any specific questions about Aztecs.
 
Not to derail the thread, but I personally love these types of posts and information. Removes some of the mystery when looking at becoming an owner.
 
Aztec Flyer's numbers are basically the same as what my Aztec cost. Over 1000 hours, it came out to $250/hr average all-in.
 
GRG55 said:
Fuel: $38,502 (I typically cruise @ 2250 RPM, slightly ROP, running 11 gph indicated per side, actual total measured fuel including taxi and climb normalizes around 28 gph +/- 0.5 gph depending on the length of trip and altitude. Time going direct point-to-point is more important to me than diverting to find cheaper fuel at out-of-the-way airports, so someone running LOP and actively managing their flight planning based on comparative fuel costs will do somewhat better than these figures.)

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What kind of speeds do you get for that 28gph?
 
kyleb said:
Insurance, Hangar, taxes?
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Those are fixed costs, not operating costs. My experience in California of fixed costs are only relevant to someone else in California.
 
GRG55 said:
Paraphrasing the late Gordon Baxter "The cost of flying today is exactly the same as it was 50 years ago...all you got..."

I spent about a year researching various twin engine airplanes before making my decision. The smaller engine twins have a lot of appeal from a variable operating cost standpoint, but consider that your fixed costs of ownership will be the same, and it seemed to me airplanes like Travel Airs and Seminoles were in high demand and not priced that much below a more capable twin like an Aztec or even some short fuselage Barons.

The twin Comanche with the 200 hp upgraded engines would have been a great option, except I wanted FIKI if I was going to regularly fly IFR where I live.
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What year is your Aztec? I didn't know that they had ever certified an Aztec for FIKI, even though they are great in the ice regardless of the weight of the FAA paperwork.
 
mondtster said:
I've never bothered to add everything up, but I use the $275-300/hour number for light twins of the Aztec/310/Baron category. It seems like my guess is pretty close to what those who have added it up have come up with.

Anyone done something similar for a Navajo?
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I used to be Director of Ops at a charter company that ran Navajos. On the PA-31-310, short body Navajos, the airframe maintenance was about the same as our Aztec. The systems are pretty much identical. I don't remember what our figures were, and as this was 25 years ago, it wouldn't relate too much. The engines were more expensive to overhaul so the reserves were higher, but you can figure that out for a TIO-540-A2C. We flew at 65% power and ran 32 gph in cruise and got 180-185 KTAS, depending on how heavy we were. They are a great plane.
 
Kristin said:
What year is your Aztec? I didn't know that they had ever certified an Aztec for FIKI, even though they are great in the ice regardless of the weight of the FAA paperwork.
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It's a 1979 'F'. Piper produced certified FIKI Aztecs but I think those were only in the last series (F) and maybe only during the last few years of production? I understood Piper was responding to the certifications Cessna started to do on their piston aircraft, the 210 and 337 Skymaster. My Aztec left the factory with boots, electric cuffs on the props, heated glass windshield plate, ice light (mounted on the left engine cowl and illuminates the wing leading edge), higher amp alternators on both engines, a modified heated alternate air intake and ice shields on the nose panels in line with the propeller arcs.

To be legal I think it has to be one equipped by Piper from the factory. For anyone considering an Aztec be aware that there are Aztecs out there with retrofitted boots and hot props but they may not be legal to fly in known ice (or at least your insurance company may have something to say about it if something happens:confused:).

You mentioned they can carry a fair ice load and I have heard that from others, so there must be something to that reputation. Regardless, I don't knowingly take the Aztec into ice and when I have come across it I don't linger at that altitude. I think a piston airplane in ice is a marginal proposition.
 
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Frogs97 said:
What kind of speeds do you get for that 28gph?
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I consistently get 165 knot TAS at 10,000 ft when my total trip fuel is running at 28 gph all in. On those trips I run 2350 RPM ROP. If I slow it down to 2250 RPM and really lean it I can get the all in trip fuel closer to 25 gph but the speed drops to just a bit better than 150 knots. For some reason the Lycomings I have owned never seem to be very happy LOP so I don't run them there.

The plane is reasonably well rigged, but by no means perfect in that respect. I am still fussing with gear door fit, and it has antennas sticking out everywhere as well as that fat Piper tail beacon which alone must be worth 1 knot :(
 
GRG55 said:
It's a 1979 'F'. Piper produced certified FIKI Aztecs but I think those were only in the last series (F) and maybe only the last few years of production? My Aztec left the factory with boots, electric cuffs on the props, heated glass windshield plate, ice light (mounted on the left engine cowl and illuminates the wing leading edge), higher amp alternators on both engines, a modified heated alternate air intake and ice shields on the nose panels in line with the propeller arcs.

To be legal it has to be one equipped by Piper from the factory. For anyone considering an Aztec be aware that there are Aztecs out there with retrofitted boots and hot props but they are not legal to fly in known ice.

You mentioned they can carry a fair ice load and I have heard that from others, so there must be something to that reputation. Regardless, I don't knowingly take the Aztec into ice and when I have come across it I don't linger at that altitude. I think a piston airplane in ice is a marginal proposition.
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That is not quite a correct statement of the law, but it is very confusing and not a lot of people fully understand it, including a number of FAA inspectors I have run into.

Aztecs were certified under CAR 3 and for CAR 3 aircraft, and aircraft certified before about 1975, the manufacturer did not have to show that the deicing equipment actually worked to get rid of ice. They were certified as not presenting a hazard to normal aircraft operation.

For aircraft certified after 1975 or so, Part 23 required the manufacturer to prove that the deicing system would actually meet certain standards of performance, i.e. handle a certain amount of "known" ice. If the manufacturer could not or did not want to do that, then the AFM would have a limitation prohibiting flying into "known" ice. There was no requirement to re-certify older aircraft, this only applied to new aircraft or if the OEM chose to go through the certification process. I do not believe that Piper ever went through that certification for the Aztec.

It is a misconception that you cannot fly an aircraft that is not certified for "known" ice, in "known" ice. There is nothing in Part 91 that so states. I have a PA-30 which was never certified for "known" icing. There is also no limitation in the AFM against flying in the ice. Hence, the only way the fed could bust me is if I crashed or came in so heavily loaded that it was half a miracle that I made it to a runway is FAR 91.13, careless and reckless, which is all the fed would have to work with.

I used to own a 1974 Aztec with boots, hot props, hot plate, deice shield, etc. The AFM said something very close to: Flight into light to moderate icing conditions is approved if the aircraft is equipped with . . ." and it went on to list about five items of equipment. I would bet that your AFM says something very similar. That is not the same thing as certified for flight into known ice, because Piper never proved that the Aztec could safely fly in the ice. Thousands of pilots however have proved that you can fly an Aztec in the ice, thank you very much!

I would take a deiced Aztec over a lot of FIKI certified aircraft any day for flight into icing conditions.
 
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Kristin said:
That is not quite a correct statement of the law, but it is very confusing and not a lot of people fully understand it, including a number of FAA inspectors I have run into.

Aztecs were certified under CAR 3 and for CAR 3 aircraft, and aircraft certified before about 1975, the manufacturer did not have to show that the deicing equipment actually worked to get rid of ice. They were certified as not presenting a hazard to normal aircraft operation.

For aircraft certified after 1975 or so, Part 23 required the manufacturer to prove that the deicing system would actually meet certain standards of performance, i.e. handle a certain amount of "known" ice. If the manufacturer could not or did not want to do that, then the AFM would have a limitation prohibiting flying into "known" ice. There was no requirement to re-certify older aircraft, this only applied to new aircraft or if the OEM chose to go through the certification process. I do not believe that Piper ever went through that certification for the Aztec.

It is a misconception that you cannot fly an aircraft that is not certified for "known" ice, in "known" ice. There is nothing in Part 91 that so states. I have a PA-30 which was never certified for "known" icing. There is also no limitation in the AFM against flying in the ice. Hence, the only way the fed could bust me is if I crashed or came in so heavily loaded that it was half a miracle that I made it to a runway is FAR 91.13, careless and reckless, which is all the fed would have to work with.

I used to own a 1974 Aztec with boots, hot props, hot plate, deice shield, etc. The AFM said something very close to: Flight into light to moderate icing conditions is approved if the aircraft is equipped with . . ." and it went on to list about five items of equipment. I would bet that your AFM says something very similar. That is not the same thing as certified for flight into known ice, because Piper never proved that the Aztec could safely fly in the ice. Thousands of pilots however have proved that you can fly an Aztec in the ice, thank you very much!

I would take a deiced Aztec over a lot of FIKI certified aircraft any day for flight into icing conditions.
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Thanks for the clarification! That's one of the best things about PoA...the knowledge exchange. Much appreciated!!
 
GRG55 said:
Thanks for the clarification! That's one of the best things about PoA...the knowledge exchange. Much appreciated!!
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I got to research this all very carefully when one of the Grand Rapids, MI FSDO inspectors told me I couldn't fly that Aztec in the ice, even though it was on our 135 certificate. I won the argument, though I had to get the higher ups in Washington to straighten out the locals.

I love CAR3 certified airplanes. You don't have all the restrictions of the Part 23 airplanes, like life limits on the wings, etc. An Aztec is one of the best, IMO.
 
Kristin said:
I used to own a 1974 Aztec with boots, hot props, hot plate, deice shield, etc. The AFM said something very close to: Flight into light to moderate icing conditions is approved if the aircraft is equipped with . . ." and it went on to list about five items of equipment. I would bet that your AFM says something very similar.
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That is still different from other manufacturers (like Beech) who retro-actively updated their AFMs to specifically say that the airplanes were NOT approved for flight in known icing.
 
Kristin said:
I would take a deiced Aztec over a lot of FIKI certified aircraft any day for flight into icing conditions.
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You ain't kidding!
 
Fearless Tower said:
That is still different from other manufacturers (like Beech) who retro-actively updated their AFMs to specifically say that the airplanes were NOT approved for flight in known icing.
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Fortunately for Beech owners, subsequent changes to the AFM are not binding unless the FAA makes it so with an AD. Beech is just trying to limit their liability.

That being said, I have less faith in a Baron in the ice than most any of Piper's products. The Baron will tail stall to the point of diving into the earth nose first. I have no run into that in a Pi[per. Not to say you can't over load a Piper with ice or crash on approach, but I haven't heard of one losing it in cruise and becoming a lawn dart.
 
Kristin said:
I got to research this all very carefully when one of the Grand Rapids, MI FSDO inspectors told me I couldn't fly that Aztec in the ice, even though it was on our 135 certificate. I won the argument, though I had to get the higher ups in Washington to straighten out the locals.

I love CAR3 certified airplanes. You don't have all the restrictions of the Part 23 airplanes, like life limits on the wings, etc. An Aztec is one of the best, IMO.
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Wouldn't your certificate and opspec supersede whatever they were trying to cite anyways?
 
mkosmo said:
Wouldn't your certificate and opspec supersede whatever they were trying to cite anyways?
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Perhaps now in the era of 80 page ops specs, but back then our ops specs were like 6 pages and didn't address the issue of icing.
 
Kristin said:
I got to research this all very carefully when one of the Grand Rapids, MI FSDO inspectors told me I couldn't fly that Aztec in the ice, even though it was on our 135 certificate. I won the argument, though I had to get the higher ups in Washington to straighten out the locals.

I love CAR3 certified airplanes. You don't have all the restrictions of the Part 23 airplanes, like life limits on the wings, etc. An Aztec is one of the best, IMO.
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You are correct that the rules are confusing. Today I did an informal poll of 5 professional pilots that I know, all of whom have Aztec time earlier in their careers (a couple of them had some influence over my decision to buy one over other twins). Every one, no exceptions, was under the [mistaken] impression that Piper had certified the Aztec for ice. I wonder if that is because of the Aztec's reputation for flight in icing conditions, or the fairly extensive de-ice provisions Piper provided, or...?

I sent them an extract of your extensive post from yesterday and told them to look up this thread if they wanted the full story. Thanks again for clarifying.
 
GRG55 said:
You are correct that the rules are confusing. Today I did an informal poll of 5 professional pilots that I know, all of whom have Aztec time earlier in their careers (a couple of them had some influence over my decision to buy one over other twins). Every one, no exceptions, was under the [mistaken] impression that Piper had certified the Aztec for ice. I wonder if that is because of the Aztec's reputation for flight in icing conditions, or the fairly extensive de-ice provisions Piper provided, or...?

I sent them an extract of your extensive post from yesterday and told them to look up this thread if they wanted the full story. Thanks again for clarifying.
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If I had to guess, I would say that Piper prioritized the Navajo line and the Seneca first and by then the sales for the Aztec were in decline so decided not to make the investment.

I still put more faith in field experience than the certification. The FAA's approach to icing is assbackwards. Since no deicing system can be guaranteed to handle all possible icing conditions, what is really needed is a known icing pilot who avoids exceeding the limits, be it a jet with hot wings or a C-152.
 
Kristin said:
If I had to guess, I would say that Piper prioritized the Navajo line and the Seneca first and by then the sales for the Aztec were in decline so decided not to make the investment.

I still put more faith in field experience than the certification. The FAA's approach to icing is assbackwards. Since no deicing system can be guaranteed to handle all possible icing conditions, what is really needed is a known icing pilot who avoids exceeding the limits, be it a jet with hot wings or a C-152.
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Although I don't go looking for trouble, endorsements of capability from former Aztec owners and pilots like you and Ted, with much wider experience than me, is worth more than any government seal of good housekeeping...
 
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