Most fuel efficient twin? [Archive]

Hodja

1st Mar 2012, 06:33

what is the most fuel efficient twin, per mile flown?
In terms of fuel cost or fuel volume?

A diesel DA42 is pretty comparable with the Tecnam in terms of nm/gal (and slightly faster), but depending on location Jet A may be cheaper pr gal than avgas.

I seem to recall that you can throttle the diesel DA42 back to some ridiculously low power setting like 40% and get 7.5gph at 120 kts, or something like that.

I really like the Tecnam btw. If only the specs weren't so much on the low side...(620 nm range, cruise 135 kts, ceiling FL150, t/o distance 450m - and a new one is still USD450k...)

cavortingcheetah

1st Mar 2012, 06:34

Full IFR Twin Commanche with logbooks in perfect order that has been hangered with decent avionics. Watch out for cavitation in the fuel tanks but find one with tip tanks and you can fly a very long way between fuel stops. It's a lovely and very under rated machine. Try the US perhaps where some of them are respected, loved and pampered.

International Comanche Society (http://www.comancheflyer.com/NS/)

BackPacker

1st Mar 2012, 07:27

If you define "fuel efficiency" as "lowest fuel burn per passenger mile", then you'd probably be looking at the Boeing Dreamliner.

However, since this was posted in PF, your mission is probably not to haul 200+ persons across the oceans. So what is your mission? 4 persons? 6 persons? 8?What is your target speed, range? Budget?

peterh337

1st Mar 2012, 08:23

620 nm range, cruise 135 kts, ceiling FL150, t/o distance 450m - and a new one is still USD450k

Those specs are poor for a going-places supposedly IFR aircraft, costing that much money.

620nm range is not much good for European touring (for $450k) unless you live in southern Germany and want to pop over to Croatia for lunch, FL150 ceiling is no good for IFR anyway because it won't get you into VMC on top in a lot of non-frontal conditions (it's similar to an Archer), the 450m t/o distance is good though.

I absolutely don't want to start another SE v. ME thread :) but take my TB20: 1300nm range, FL200 ceiling, 450m takeoff roll, and the new cost (2002) was c. US$300k. A potential Tecnam owner doesn't need a PhD to be aware of this stuff.

Ever since Mr Thielert and Messrs Diamond have comprehensively p1ssed all over the twin engine options, I can see the Tecnam being popular with ATPL schools whose prime objective is to fly as slowly as possible (because they charge by the hour, and the punters have to pack X hours in their logbooks) consistently with going just fast enough to fly NDB holds in 30kt crosswinds without getting blown away sideways ;) , who don't care about going places, and who do everything at low levels.

But the options for a serious private pilot are rather poor, which is why I have not done anything "ME" myself. You have a choice of 1950s airframes, most of which were built in the 1960s or 70s, or the DA42 with its engines which are either dodgy or as yet unproven, and that's about it. It's a real shame because the DA42 could have been a revolution.

Rod1

1st Mar 2012, 10:04

If you are interested in efficiency have a look at this;

Twin-R (http://www.love4aviation.com/Aircraft/Twin-R.html)

Only of academic interest in the short term. Dyn Aero went bust a few months ago with the twin ¾ of the way through its certification. The company has been bought as a going concern and spares etc are back up and running but no word yet on the plans for the twin. The efficiency comparison charts make interesting reading though.

Tecnam are reported to be working on a Rotax 914 turbo version which should make a big difference to the aircraft.

Rod1

daytrader1

1st Mar 2012, 10:05

thanks for the feedback guys. Backpacker, I am hoping to use the plane to primarily fly between a cattle property and city roughly 400nm away. Speed wise, anything faster than 150kts would be desirable. Budget wise I am undecided, but have noticed that here (Australia), there seem to be a lot of cheaper twins coming onto the market.

BackPacker

1st Mar 2012, 11:08

What's the runway like at that cattle property? And is 100LL available there? (I assume yes, since you're doing this in a Cherokee six already, but at what cost? If you could have an aircraft that would run on regular car diesel and Jet-A, or regular car unleaded, it might make operations a lot simpler.)

And do you need basic IFR for the occasional cloud, or a serious IFR tourer, de-iced and everything?

And what's the terrain in-between? If you were to keep on flying a single and had an engine failure, what would be the chances of survival? Because to be honest, this sounds like a typical job for a C182 with an SMA diesel or something similar to that.

Captain Smithy

1st Mar 2012, 12:00

One of the problems with twins is the horrendous maintennce costs. You might find yourself better off sticking with what you currently fly... :suspect:

Fuji Abound

1st Mar 2012, 12:07

In a slightly backward country such as Australia http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif you are also going to need to consider the ability to service the engine - there may not be that many approved diesel service agents.

As an example the DA42 has its advantages but even in Europe there are places you would not want to develop an engine fault.

Mickey Kaye

1st Mar 2012, 12:53

"Tecnam are reported to be working on a Rotax 914 turbo version"

This aircraft could already be a bit of game changer in the IR instrcutional market place and if turbo charged and/or FIKI it might be suitabel for twin piston AOC ops.

silverknapper

1st Mar 2012, 14:31

As Peter says, the Tecnam is fairly useless for touring. A useful load of 400 kg means you'll never be able to carry 4 adults anywhere, indeed 3 with fuel will be a challenge.
140 knots is too slow for a twin IFR tourer. You may not be burning much gas but you are travelling at single engine speeds. And the range is dreadful.
Also the limiting speed for the gear is 90kts. Try flying an approach into any reasonably busy airfield at under 90 knots and I'd take a book to read while your being held.
I'm sure it's a good training aircraft for schools but for hard IFR it's just not suitable.

Big Pistons Forever

1st Mar 2012, 14:57

There are 3 sets of numbers that matter to an aircraft owner:

1) Useful load, so that you have enough capacity to carry your typical load

2) Overall performance, so that the aircraft has the range and speed appropriate for your typical trip and the runway performance necessary to operate from your typical airfield.

3) Total ownership costs. Fuel use is only one part of the equation. A rough but nevertheless surprisingly accurate predictor of costs is when comparing like performance singles and twins double the cost of the single. So for example a Seminole will be twice the total costs of an Arrow and and an Seneca 2/3 will be twice the cost of a Lance/Saratoga for the same miles flown. I would suggest that for a Cherokee six the same equation would roughly apply. Double the money for approximately the same load, range and runway performance.

The Twin Comanche is a very impressive aircraft with very good fuel efficiency and simple and economical 4 cylinder engines. However the cabin is smaller and the payload much less then a Cherokee six and parts are getting harder and more expensive to find. To equal the capability of the Cherokee Six I would say you would have to get an Aztec.

Hodja

1st Mar 2012, 15:33

Also the limiting speed for the gear is 90kts.Yikes, missed that one - that's an amazingly low number.

(in comparison the DA42 gear can be extended right up to Vne (= 194 KIAS) and retracted at 156 KIAS - pretty good)

cavortingcheetah

1st Mar 2012, 15:48

Perhaps a little thirstier but a really lovely machine if you're in Cessna country was the Cessna 310R - not the Q. You'd need to check the log books for undercarriage maintenance on those. It's a weak spot but then it's a six seater and unlikely to have been on a training licence.

seat 0A

1st Mar 2012, 16:43

I would second the choice for a twin comanche.
You can find them really cheap nowadays. Expect to pay around 80.000 US for a really nice one with low hour engines.
They're great to fly and really give you a lot of speed and joy for 16 GPH @ 160 kts.

silverknapper

1st Mar 2012, 16:46

I would agree with the BPF and CC. A look at an older "old school" twin such as 310 or Baron could well be a good idea. A nice low hour Baron would be attainable for a surprisingly reasonable sum. If you buy well then any difference in fuel costs can be put aside
Someone once said something to me regarding fuel costs for light aircraft which made a lot of sense. It went along the lines of sorting out all your fixed costs first. Best deal on insurance, within reason keep it where hangarage is reasonable etc etc. Then if you want a twin it shouldn't cost a lot extra per year. I know these should be obvious but I have seen a few people who haven't been on top of all their fixed costs and have been handing over a lot more than necessary.

Rod1

1st Mar 2012, 17:19

“Best deal on insurance, within reason keep it where hangarage is reasonable etc etc.”

That might work outside the EU, but most privately owned aircraft which do 100h a year, the fuel cost will be more than the rest of the costs put together (in the EU). Even my Rotax powered machine burning 18.5lph of mogas - fuel costs are 52% of the yearly costs (based on 100hours a year).

Rod1

Charles E Taylor

1st Mar 2012, 18:25

It might be this!

CriCri - Interview - YouTube

Charlie

frontlefthamster

1st Mar 2012, 20:10

Probably, though my compatriots won't thank me for saying this, the 787.

I only mention this because the OP hasn't specified his mission in sufficient detail to answer more clearly.

What load?

How far?

Is speed important?

Field performance?

OEI ceiling?

Overwater speed?

...and so on.

(the 787 is quite nice to fly too, as it should be, though I'm sorry they've handled pitch-power couple the way they have and I'm not sure that Boeing have done all they should with some systems; the performance calculation looks like something from the 1980s).

frontlefthamster

1st Mar 2012, 20:19

OK, more seriously:

Some Senecas are pretty good all-rounders; avoid those which have been thrashed by flying schools and the V with it's shocking DOW/MTOW. The handling is never better than OK, and at low speed is, in my view, only just reasonably certifiable (hence all the landing accidents).

The Baron is a delight. Do not buy one if you open and read your bank statements because you have to.

If you have a load to carry and want to feel proud, bite the bullet and buy a Navajo.

To join one of the happiest bands of owners I've met, go for the Twin Commanche, but accept that it is a machine which focuses on range, not payload. The owners club is a must.

A GA7 is very nice, albeit slow, but good ones are VERY hard to find.

Avoid all the modern stuff; it's down to a price and a weight, not up to a standard.

AdamFrisch

2nd Mar 2012, 03:43

If one wants range and efficiency in an "old" design, then look no further than to the Piper Aerostar. Yes, it's known for being a fast rocket (the fastest, in fact), but that also means it's the most efficient. The 700 will do 260kts on 45-50gph. At 205kts, it'll sip 25-30gph. Go down to fast single engine speeds, around 140-150kts, and the Aerostar will probably not drink much more than 15-20 gph (a guess). That's rather impressive. With a standard 165gal, or optional 210gal tank, it's easy to see just how far one could go.

To get efficiency there is only one thing you can do - reduce drag. Aerostars have one of the narrowest cross sections and a very high wing loading, so that's why the have minimal drag.

http://www.adamfrisch.com/images/aerostar.jpg

Hodja

2nd Mar 2012, 04:21

Go down to fast single engine speeds, around 140-150kts
Although that's the Aerostar's stall speed innit'? ;)

sternone

2nd Mar 2012, 07:14

There are no fuel efficient twins.

lotusexige

2nd Mar 2012, 14:42

Well, I've seen a Rutan Defiant for sale recently in the UK.

Pilot DAR

2nd Mar 2012, 14:48

I am surprised that the Cessna 337 has not been mentioned. Though not equal to a Twin Comanche is some regards, it will exceed in a few others...

bookworm

2nd Mar 2012, 16:11

[Twin Comanches] are great to fly and really give you a lot of speed and joy for 16 GPH @ 160 kts.

Lean more. 13 GPH (OK, that might give you 155 kt).

Though not equal to a Twin Comanche is some regards, [the C337] will exceed in a few others...

Like the din... ;)

Another devoted Twin Com fan.

Pilot DAR

2nd Mar 2012, 17:46

Yes, I'm a Twin Comanche fan too, as long as you're not trying to taxi in between high snow banks, or help someone's grandmother get aboard!

MT props make it a real preformer too!

http://i381.photobucket.com/albums/oo252/PilotDAR/Jims%20DAR%20Testing/IMG_4394.jpg

http://i381.photobucket.com/albums/oo252/PilotDAR/Jims%20DAR%20Testing/IMG_4399.jpg

achimha

2nd Mar 2012, 19:23

The Tecnam P2006 is a pure training aircraft, not suitable for anything else IMO. Range, speed, operating ceiling and surprisingly poor finish quality wouldn't justify the $450k as a personal aircraft.

A Rotax 914 (i.e. turbo) version of the P2006 wouldn't be that great either because first of all, the 914 got a shorter TBO than the 912S and most importantly, the 914 does not like AVGAS 100LL.

The TwinCo is a great aircraft but that is no secret so used market prices are quite high for such an old bird.

Big Pistons Forever

2nd Mar 2012, 22:28

I am surprised that the Cessna 337 has not been mentioned. Though not equal to a Twin Comanche is some regards, it will exceed in a few others...

The problem with the C337 is the pilots peripheral vision. When you put the paper bag over your head so nobody can recognize you in such a god-awfully ugly airplane :E, everyone just cuts two eye holes in the front. The problem is you can't see out the side without turning your head, thereby creating a danger of hitting something :ouch:

AdamFrisch

2nd Mar 2012, 23:57

I completely disagree about the Tecnam. If you want to go from A to B with twin safety at single engine prices, this is the only thing that can do it. Yeah, the DA42, but it's more than twice as expensive to buy and doesn't go any faster. Also, even in places where they don't have Jet A1, you can bet they'll have Mogas at a local gas station. Mogas is available everywhere.

achimha

3rd Mar 2012, 04:15

Also, even in places where they don't have Jet A1, you can bet they'll have Mogas at a local gas station. Mogas is available everywhere.

If you're going to GA airfields only, you might get Mogas or they might let you be creative with jerry cans and a taxi but if you fly to a real airport, I don't know of any airport that offers Mogas or would let you bring in your own Mogas (a lot of jerry cans btw). Given that the P2006's endurance isn't great at all and personal aircraft are used for trips to remote places, I still don't think a Rotax 914 equipped P2006 would provide much value.

A twin engine ceiling of 15000ft and a single engine service ceiling of 7000ft isn't even enough to cross the Alps safely. In my view, the P2006's mission capability is that of a low end single.

I would always prefer a used D42 (if you like modern and fuel efficient planes) or one of the old AVGAS guzzlers when it comes to a personal twin.

peterh337

3rd Mar 2012, 06:25

Mogas may be "available" everywhere but usually only in jerrycans, and the business of transporting jerrycans makes it impractical for serious use. For example my usable tank capacity is 86 USG (325 litres) which would be about 17 jerrycans, each of which is so heavy I can barely lift it and would need a sizeable vehicle to transport them. Also no normal garage would allow that many to be filled - AFAICS.

A twin engine ceiling of 15000ft and a single engine service ceiling of 7000ft isn't even enough to cross the Alps safely. In my view, the P2006's mission capability is that of a low end single.Very much so; its ceiling is too low. If the ceiling is really 15k, and that (depending on the cert regime) is usually defined as +100fpm climb rate, then you are looking at ~FL130 as the highest practical altitude at say ISA+10 (typical southern European / Alpine summer conditions) and that is below the Eurocontrol MEAs in that region. For example this route (http://www.peter2000.co.uk/aviation/kithira/egka-ljpz-big.jpg) has an MEA of FL140 and that is one of the lower ones. (Also that route is too long for it). It would be flyable VFR but only on very calm days when there is no chance of a downdraught.

But I think they know their market. It is FTO training and surveillance.

Re cost of capital, I really think this needs to be disregarded on a private purchase because if you took that into account you would die very rich not having done anything remotely interesting :) What cannot be disregarded is depreciation.

Hodja

3rd Mar 2012, 06:48

Not to mention, that jerrycan refilling is a bit of a mess, and potential safety hazard. A lot of airfields even prohibit jerrycan refuelling on the ramp.

I agree. Unless mogas becomes directly available on the airfields, mogas isn't really a viable option. I see mogas as a great "fallback option", ie. if you're stuck somewhere w/no avgas options for hundreds of miles.

Mogas is available everywhere.
So is diesel btw. (good for the SMA's/Thielert-Centurion and probably the Austro as well)

peterh337

3rd Mar 2012, 06:58

I see mogas as a great "fallback option"

What would actually happen if you put normal car petrol into the tank, for an IO-540-C4 for example?

Presumably, detonation would not occur at the low CHTs present during takeoff, IF you transitioned to a cruise climb ASAP.

AdamFrisch

3rd Mar 2012, 09:39

Any old twin worth it's salt is going to guzzle 25-30gph Avgas. Add to that a minimum cost of $25-30k per engine on overhaul, plus all the rest of the stuff you get stung with on old twins. I've shelled out $35K this year alone in maintenance (bless her heart). Even a financed Tecnam at 5% interest is going to be more cost effective at just 100-150hrs. Everything above that is gravy.

On a LA to NY trip of 2100nm, the Tecnam will burn $825 in Avgas, or $525 (this is airline competitive prices) in Mogas. Compared to my Commander at $2062 in Avgas. Same speed, same power setting. It doesn't take many hours before you've saved enough to pay for that monthly payment...

And come overhaul, you're looking at half the price or less compared to any Lycosaurus

peterh337

3rd Mar 2012, 09:57

Any old twin worth it's salt is going to guzzle 25-30gph Avgas

Should not be as much. I am below 10GPH on high altitude flights, so 2x that. 30GPH is just being ignorant of engine management, or flying a turbo installation at 75% to 85% of max power.

But cost savings are not much good if you are stuck in icing conditions.

Hodja

3rd Mar 2012, 12:22

What would actually happen if you put normal car petrol into the tank, for an IO-540-C4 for example?
That's a good question. An acquaintance of mine flies mogas in his IO360 DA40F. (covered by a mogas STC) But I'd personally be wary of doing this on a IO540.
Any old twin worth it's salt is going to guzzle 25-30gph Avgas
Should not be as much.
I'm not sure why, but I generally hear even higher consumption figures quoted for these old twin guzzlers. A friend of mine flies a C340, and it's running ~35gph at 75%. Try that with non-US avgas prices, and you're talking serious cash for even trivial trips. Although as people have mentioned in this thread, what's really killing the old twins are the damn maintenance bills.

I've shelled out $35K this year alone in maintenance (bless her heart).
Adam, please tell us it's been worth it after all! :ok:

peterh337

3rd Mar 2012, 13:48

I'm not sure why, but I generally hear even higher consumption figures quoted for these old twin guzzlers
I suspect it is because the ones you heard about are flown by pilots who are ignorant of modern operating procedures.

The engine doesn't care if it is in a single or a twin.

But yes an old twin will be relatively expensive to run because

- you have 2 engines and some ~80% of the 2nd engine is used to pull along that engine, plus the now substantially larger aircraft (longer wings are needed because the engines take up a fair bit of them, for example)

- most twins are very old and an old plane will tend to have a significant appetite for airframe parts (true for old singles too of course but a twin has more bits on it)

Big Pistons Forever

3rd Mar 2012, 15:08

I suspect it is because the ones you heard about are flown by pilots who are ignorant of modern operating procedures.

Yup everybody is ignorant about the operation of engines except you :rolleyes:

Adam flies an Aero Commander 520. It has GSO 435 Lycoming engines fitted with pressure carburators. His reported fuel flows are the best you are going to get from this engine. All the modern engine analysers in the world are not going to make any difference as this engine won't run smoothly at LOP.

In any case all the private pilots I know who operate twins are quite aware of how to run the engines economically because they are the ones who have to pay the big bucks when the fuel truck pulls up! They all have and use engine analyzers.

peterh337

3rd Mar 2012, 15:29

I don't think you got what I was getting at, BPF :ugh:

AdamFrisch

3rd Mar 2012, 15:59

Adam, please tell us it's been worth it after all!

Yes it has for sure for me personally, but it's like people say: if you buy an aircraft cheaper, be prepared to spend as much again the first year to bring them "back". This has proven to be the case. Even though I knew that, it's only when you're actually faced with the bill that it hits home. But no regrets at all, even though this is money you can't get back if you sell it.

My squawks are pretty much all eliminated and ironed out now, so this year the costs will only be cosmetic, hopefully. But just to give an idea: a new paint job done right is $18K, an interior is $5-10K. Any new avionics installation is in the thousands etc. So it's not for the faint of heart.

silverknapper

3rd Mar 2012, 17:27

On a LA to NY trip of 2100nm, the Tecnam will burn $825 in Avgas, or $525 (this is airline competitive prices) in Mogas

With how many stops? 4 minimum, with all seats full 7? Obviously flying in the US is more reasonable but 7 stops in Europe starts to stack up. Especially if one has to utilise proper airports, which on a long international flight one would have to to be assured of completing the mission. Providing icing isn't an issue. Also the 2100 nm will take a looooong time.
The right avgas burner should be around 20-24 gph. Anymore than that would be discounted in my search for cost reasons.

englishal

4th Mar 2012, 12:27

If I wanted a twin (well I do...but...), I'd buy something like an old Seneca II (as it has turbos on and is pretty capable if you get de-ice boots etc...) relatively cheaply. I'd then overhaul the motors, put 3 blade props on, re-upholster and paint. Then depending on how flush I felt, I'd fit a new avionics suite.

So for £150,000 you could end up with a sweet "as new" aeroplane with modern avionics in great known condition.

Yep it will burn significantly more than a DA42 but at the end of the day if one buys a new aeroplane, you're going to lose a shed load of money in the first few years anyway, and that is more then equivalent to the fuel saving.

peterh337

4th Mar 2012, 12:40

I believe both have the same 8.5:1 cylinders

That is what I was getting at. I cannot see a problem (apart from it being illegal).

Don't forget the 1999kg STC, Englishal ;)

Jan Olieslagers

4th Mar 2012, 13:02

if you fly to a real airport, I don't know of any airport that offers Mogas

I don't know your definition of a REAL airport, nor why anyone should want one. But there's plenty of aerodromes with mogas available, especially round yours. Check it out at http://www.dulv.de/app/so.asp?o=/_obj/A37ED09C-9074-41B0-8AB0-4FB785AC174D/outline/D_mogas_170111.pdf for just one source. Have to admit I know of no airfield with a Mogas pump in my own country.

Pilot DAR

4th Mar 2012, 13:10

I'd buy something like an old Seneca II

Oooo, though I'm generally a fan of some "legacy" types, NOT a Seneca II, or a number of other Pipers of that era. I have had first hand experience with very expensive repairs required for corrosion damage, because Piper would not support that type, with the required replacement parts. I quote the Piper Tech Rep: "Sir, that's a 40 year old airplane, we have not seen it in 40 years, and we don't want it in the air."

With that policy toward product support, I'm really happy I own the second most common Cessna ever!

421C

4th Mar 2012, 15:19

an old twin will be relatively expensive to run because

- you
have 2 engines and some ~80% of the 2nd engine is used to pull along that
engine, plus the now substantially larger aircraft (longer wings are needed
because the engines take up a fair bit of them, for example)

- most twins
are very old and an old plane will tend to have a significant appetite for
airframe parts (true for old singles too of course but a twin has more bits on
it)
Neither of those reasons are true.
Two smaller engines mounted on the wings are less efficient in weight, drag and specific fuel consumption than one larger one, no doubt. But it's nothing like 80% of the 2nd engine. That's ridiculous. Take a basic airframe available in twin and single versions. A 2x200hp Seneca vs 300hp Saratoga. The Seneca is faster. It is not substantially larger, it is about the same size. For that matter look at the Tecnam 2x100hp vs. 160-200hp singles.

I have never understood your theory that an old plane is expensive to maintain because of airframe parts. I have owned 2 old twins and the airframe parts cost has been negligible. I don't believe a properly maintained old twin cost more to maintain today than it did 20 years ago. However, they do cost a lot to maintain because they are complex and labour-intensive. There's more to go wrong and even trivial things can take a few hours labour before anything has happened. What is hugely expensive is taking a badly maintained old twin and fixing it. The other mistake is to base maintenance cost expectations on what the purchase price of the airplane is. The old twins have depreciated a lot in real terms but that hasn't changed the maintenance cost from the time in the 70s when they were the equivalent of $1-2m corporate airplanes.

Oooo, though I'm generally a fan of some "legacy" types, NOT a Seneca II, or
a number of other Pipers of that era. I have had first hand experience with very
expensive repairs required for corrosion damage, because Piper would not support
that type, with the required replacement parts. I quote the Piper Tech Rep:
"Sir, that's a 40 year old airplane, we have not seen it in 40 years, and we
don't want it in the air
There are thousands of Senecas flying about giving dependable service. In my 10 years of ownership I never had a part problem. And at least Piper didn't succumb to an equivalent of the SID debacle which has cost twin Cessna owners $100k each in some cases - ask any Australian C310 owner...

I have yet to hear of any consistent set of anecodotes about parts cost and availability for any old aircraft. They always contradict themselves. One person says
"the factory was struck by a giant meteorite in 1971 and vaporised. The company then went bust and all the drawings were burned. Parts sourcing is thus a nightmare for this Type"
Then someone replies
"Nonsense. The owners' association has a list of PMA suppliers and every single part can be sourced just as quickly and cost-effectively as for a type still in production"

Pilot DAR

4th Mar 2012, 15:38

I agree that different owner's experiences with airframe parts availability can vary greatly.

I was not involved in either of the two mentioned parts availability problems as the owner, but as the DAR (like FAA DER) asked to provide approval for a "made part", when Piper would not support the aircraft with the required parts. The quote I reference was spoken by Piper to me.

The Seneca II I was involved with was unairworthy as a result of corrosion - just certain parts, but critical ones! If there were any alternative sources for the required parts, a great effort expended, before I got the call, would probably have revealed it/them.

Similar challenges with Cherokees, and in particular an Arrow I was asked to inspect, have resulted in a similar response from Piper.

Yes, Cessna has mandated comprehensive inspections, which, in the era of "aging aircraft" for larger types, does have some merit. I believe that Cessna will still provide the required parts. (though I have not personally checked this). I attended a Cessna presentation on this subject, and nothing in that presentation lead me to think that Cessna did not want it's legacy twins flying, they were just intent on assuring their airworthiness. I understand it's beginning to filter down to the singles soon too.

I did check with Piper myself, and was twice told "No". That makes an impression upon me....

Contacttower

4th Mar 2012, 18:00

My vote goes for the Twin Com; great aircraft.:ok:

peterh337

4th Mar 2012, 19:18

I have never understood your theory that an old plane is expensive to maintain because of airframe parts. Obviously that's not true, so it could not have been a theory of mine.

It is the accumulated cost of poor maintenance (specifically poor lubrication, and corrosion) which makes an old plane potentially much more expensive to bring up to a "perfect" standard after it is bought by the next punter.

There are obviously exceptions, depending on whether the previous owner was diligent or not, but most owners do not maintain on a money no object basis. Most let things wear out and then they flog the plane. Same with cars.

But firstly few people are going to "totally fix" a 30 year old plane they have just bought, so they will be running along with a part of the legacy they bought, and secondly corrosion is something that does get increasingly expensive with airframe age (relative to hangarage history obviously, etc). That is just actual practice out there.

I have owned 2 old twins and the airframe parts cost has been negligibleAfter the total-stripdown rebuild you had done on your 421C (ballpark cost £100k plus avionics?) I would have expected it to be close to zero for the rest of your flying life :)

Re the 80% fuel burn overhead, what figure would you offer?

AC-DC

4th Mar 2012, 20:41

The Twin Com is the aircraft that will do the job for you in the most efficient way. Fuel consuption will be 15gl total @ 160 knots (indicated at low level). In Oz there are some very knowledgeable people who will be able to you if you have problems, more over, they even produce their own parts (due to CASA rules). As for parts, some are more difficult to obtain than other but all are available, especially as Piper said that they will start to produce parts as needed, even if they have to reverse engineer them, price unknown.
If you decide to go for the twin Com feel free to contact me (by email) and I will introduce you to some people that will make sure that you won't get burnt, they can find the aircraft for you, will inspect and repair it as needed if you instruct.

Pilot DAR
These 3 bladed props, are they FAA STCed or just during development? How much are they? Some people will give their right arm to have these on their aircarft.

Thanks

peterh337

5th Mar 2012, 15:50

If you are a really good engineer (like you are) and you live in a reasonably dry climate then there is no reason why 50 year old airframes should not be fine.

Being in the USA also helps. One of the things which costs money in Europe is that there is no authorised procedure for replacing bushes which are push-fit inserted into aluminium brackets. You have to either buy the whole bracket with the bush (typ. £1000) or you do a job off the books whereby you either (a) ream out the bush a bit and machine up a new pin or (b) push the bush out and machine up a new one and just buy the usually cheap bolt which goes into the middle of it. Some 99% of airframe parts are trivial to fabricate if you have a lathe and possibly a turret mill, but cost a fortune to replace officially. Under the right regulatory regime you just machine them up and an A&P/IA signs it off.

The other factor is whether there is a CMM (component maintenance manual). If you are totally anal about it, no CMM means the component cannot be worked on at all. I bet the 50 year old planes in question here were flying before anybody could spell "CMM". On things like Spitfires (AIUI) you can fabricate replacements if you have the manufacturing drawings, and for a Spit they do exist.

But then a Spit is not on an ICAO CofA which alone makes a massive difference to what you can do. We need to be comparing like for like.

Here in Europe, EASA-reg, the flexibility is gone unless you do stuff off the books. Put that together with crap lubrication (just squirting an aerosol lube into the bearings/bushes, without dismantling them and cleaning them) and that's why people with 30 year old C152s may be paying £7k to get them through the Annual.

Big Pistons Forever

7th Mar 2012, 03:38

Pilot DAR
These 3 bladed props, are they FAA STCed or just during development? How much are they? Some people will give their right arm to have these on their aircarft.

Thanks

MT has an STC for 3 blade props on the Twin Com

cavortingcheetah

7th Mar 2012, 06:53

One of my personal favourites is the Rockwell 680/685. There's quite a lot of them in use in the Caribbean and Bahamas flying the inter island charter routes. It's fun flying too and the high wing is an advantage in tropical sunshine. I suspect though that you'd have to do a lot of research on the marque in order not to get slightly stung. The simple selection has to be the Twin Commanche. It has it's foibles though so a knowledgable conversion instructor, experienced on type, is a good idea.

Flaymy

7th Mar 2012, 14:14

I would suggest accepting the extra 20 litres an hour and just go for a twin version of what you have already!

Find a decent Seneca III. Better than the II in a few ways - extra 20 hp on take-off or EFATO, better cockpit layout, better weights (I think the MZFW of the II is limiting, although I only have a few hours on that so don't quote me).

Basically Piper never improved the Seneca from the III, just made it heavier with gimics.

The Seneca will be lovely and familiar to you. It will be cheap to buy (probably under US$100k) which makes up for the fuel burn over the Diamond or Tecnam, although not as cheap as a Comanche. However it won't be as old as the Comanche either, and it is larger. The cabin will of course be very familiar to you, as I understand will the handling.

The Seneca III is a great aircraft.

Mickey Kaye

8th Mar 2012, 20:00

Still think the the lower running costs of the P2006 will replace alot of old iron. We are still on the mark one version of the aircraft. Things like low service ceiling and range may only improve with further revisions.

I would be very surprised in Tecnam don't put the new fuel injected rotax on the airframe in 912 and all probability 914 form. This will reduce fuel burn further, increase the range and possibly increase the service ceiling.

AdamFrisch

8th Mar 2012, 22:51

I agree with you Mickey. Apparently the new 912iSc has a 30% improvement in fuel economy. Granted, this is Bombardier marketing speak, so might not be entirely truthful. But a twin that burns 7gph in total, and can all of a sudden go 900nm on 62 gal of fuel, is going to make some inroads. I'd get one of those when they become available in a heartbeat if I could find the cash for it.

Big Pistons Forever

8th Mar 2012, 23:17

From a dollar vs capability calculation, twins represent a pretty good deal.

For example Barons are selling for less than the same model year Bonanza's, yet are 30 knots faster, carry more, have the redundancy of 2 engines, 2 vacuum pumps, 2 alternators, and many have deice and radar fitted.

Yes the total ownership cost will be more but you are also getting a lot more airplane. The big problem is finding a twin that has been properly maintained. There is a lot of neglected junk out their but a twin in good nick will not cost significantly more to maintain than the equivalent single and so insurance and fuel represent the biggest source of extra expense.

I don't get the P2006 for a private owner. If you are over 55 years old, for the price of a P2006 you could get a nice Baron/Aztec/Cessna 310 and pay for all the fuel and maintenance for the rest of your flying life and still be ahead.

AdamFrisch

8th Mar 2012, 23:22

I don't get the P2006 for a private owner. If you are over 55 years old, for the price of a P2006 you could get a nice Baron/Aztec/Cessna 310 and pay for all the fuel and maintenance for the rest of your flying life and still be ahead.

Only if you never fly it, BPF. At just 100-150hrs per year, the Tecnam will be cheaper to own, even when financed, compared to a paid off dinosaur twin.
I've done the spread sheet.

Big Pistons Forever

9th Mar 2012, 03:05

Only if you never fly it, BPF. At just 100-150hrs per year, the Tecnam will be cheaper to own, even when financed, compared to a paid off dinosaur twin.
I've done the spread sheet.

You would have to spend another 450 K to buy the P2006. Financed, that is at least 3500 USD a month even with a 20 yr pay out. Plus probably an extra 200 USD a month for the higher hull insurance premium. 15 hours a month at 25 gal/ hr is 1875 USD vs 15 hours at 10 gal/hr for the P2006 which is 750 USD. The delta is over 2500 USD a month or $30,000 a year. Yes there is going to be more maintenance with the older twin but over a 20 year life it is hard to see how you come out ahead with the P2006....

peterh337

9th Mar 2012, 05:22

FWIW, I bought a new plane 10 years ago, for £230k inc VAT, and have never regretted it.

The warranty bill came to about £100k (largely because they built the panel (http://www.peter2000.co.uk/aviation/kithira/final-panel-big.jpg) out of a pile of "serviceable" avionics which came back from customers, I am 99% sure) but as I say that was met under warranty :)

And then I had really minimal unscheduled maintenance for 10 years.

So a case can be made for buying something new. It probably depends on how lucky you feel :)

But the Tecnam twin has a more serious issue of having insufficient performance for IFR long distance flights around Europe. I won't get you high enough for sure, and arguably it won't get you far enough in the often sparse matrix of avgas v. Customs we have here. Nobody is going to pay that kind of money for that capability. By the time you have that much dosh to spend, you will hopefully have been kicking around this business for a few years and you will know what mission capability is required for what. And if you are a fresh PPL with loads of dosh you will do what everybody else does and buy an SR22 :)

They are aiming at FTOs and government surveillance stuff - just like Diamond with the DA42. There are actually relatively few private DA42 owners, and all those I know personally are deeply unhappy with it (mostly because of the Thielert business, but also due to general low QA) and even less happy with the factory and the customer service they get from there.

AC-DC

9th Mar 2012, 06:10

BPF

Are you sure about the MT STC? None of us seems to know about it inc. AP&IAs.

Rod1

9th Mar 2012, 11:33

Rotax have just launched the new fuel injection and ECU control module for the 912S. This is clamed to improve fuel economy by a significant amount so may go some way to solving the range issue. TBO is 2000h, not the 1500 which was quoted in an earlier comment.

Rod1

Jan Olieslagers

9th Mar 2012, 11:46

And I am not the only one to distrust electronics even in a car engine, far worse for flying. One of the common factors of success of the current Rotaxen and the older US'an engines is the lack of electronics (with a little exception for the ignition modules and the regulator in the Rotax).

BackPacker

9th Mar 2012, 11:57

This is clamed to improve fuel economy by a significant amount so may go some way to solving the range issue.

I just read the AVweb announcement. The only claim I could find was:

BRP claims up to 30 percent lower consumption than like-power aircraft engines.

So I think they're comparing the 912iS to the likes of the O-200, and claim 30% lower fuel consumption than those. Well, duh. That's what the 912S already achieved.

I can't see any claim that the 912iS will have a significantly lower consumption than the 912S. And I would not consider that likely anyway: The altitude-compensated Bing carburetors on the 912S are already pretty efficient. Fuel injection offers a lot of benefits, but significantly lower fuel consumption isn't one of them.

Power output will be 100 HP too, by the way. Exactly the same as the 912S.

So betting on a better future for the P2006 just because there's a 912iS now is not a good idea, as far as I can see.

As far as I'm concerned, the 912 and 912S are great engines for two-seater VLAs and MLAs, and the 912iS will offer a few operational and maintenance benefits over the 912S. (But no significant performance increase.)

But putting two of them in a four-seater twin is just overreaching. Particularly since the whole contraption has to stay in the air if one fails.

Consider this: A realistic four-seater (not a "2+2") single needs about 160 HP. So any four-seater twin should require at least about 160 HP in each engine as well, to have any realistic flight performance on one engine.

And I am not the only one to distrust electronics even in a car engine, far worse for flying.

Rotax has an excellent reputation for reliability. Fuel ignition is something I think they've worked on for a long time. I don't think this has been some skunk works project where they are just trying out something. So for now I'm giving them the benefit of the doubt (although that doesn't buy them much since I am not in their target market segment).

I would be interested in the ECU though. Did they design something from scratch, or just bolted on a stock standard automotive (e.g. Bosch) ECU, or something in between?

AdamFrisch

9th Mar 2012, 12:19

Well, by now we should all have learned that if we want a 4-seater with mission capability, we need to buy a 6-seater. It's unfair to criticise any aircraft for not being capable of filling the seats, filling the tanks and go 1000nm. There is no aircraft that can do it.

The Tecnam is no exception - it's a 2 seater twin with full capabilities, or 4 with less. That's fine by me as I fly on my own 90% of the time. I feel that unfairly, just because it's a twin, it gets compared to Senecas, Barons and King Airs that have over twice as much power. It's not that kind of aircraft. It's reinvented an old class and should be compared the long forgotten Wings Derringers or Miles Geminis, rather.

peterh337

9th Mar 2012, 13:00

BRP claims up to 30 percent lower consumption than like-power aircraft engines.

I don't see how they can deliver a 30% better SFC than another petrol engine operated at peak EGT or LOP.

The old Lycos already outperform any petrol car engine, of any era, on SFC. A higher-RPM engine like a Rotax should be slightly worse than a low-RPM direct-driven engine due to greater friction losses.

Fuji Abound

9th Mar 2012, 13:21

Seems to me some are still convinced we have proved particles can travel faster than light. It is a challenge rewriting the laws of physics and when it comes to the most basic (such as the fuel efficiency of engines and light aircraft) you have a real job on your hands.

You will get some efficiencies from automated and metered injection but even these are not going to be substantial, beyond that the physics of a combustion engine dont change a great deal from one make to another. In exactly the same way, make the fusealage more narrow, bin the spats etc all will have a reasonable impact on the engine(s) required and in turn on the ful burnt, but you get nothing for nothing. Some like sitting shoulder to shoulder in a Mooney and cosying up, others like to keep their friends a little further away and if they are big fat American friends will probably fly a Cirrus!

So in short I am afriad there really is no free lunch, the P2006 achieves its efficiency largely in the ways I have suggested and perfectly good I am sure it is but it is not because there is any amazing new technology that is at work - just the tried and tested, keep down the weight, keep down the drag and operate the engine at LOP or there abouts and anything you do beyond that will not amount to much of an improvement.

Mickey Kaye

9th Mar 2012, 13:47

I really don't see this in the real world.

My findings are that the fuel burn is significantly less with a 912 than a continental.

At my local flying school we bank on a fuel burn of about 20 ltrs an hour for the o-200. The 912 about 14.

peterh337

9th Mar 2012, 14:00

Probably largely because the Conti is flown full-rich. That is worth about 30% :)

AC-DC

9th Mar 2012, 20:36

Adam Frish wrote:

It's unfair to criticise any aircraft for not being capable of filling the seats, filling the tanks and go 1000nm. There is no aircraft that can do it.

The Comanche 260C (and maybe the 260B) will take 4 people, full tanks (90gl), some bags and do 1000nm. The twincom with tip tanks will do the same.

NazgulAir

9th Mar 2012, 21:08

...and if you have a 260C with tip tanks such as ours, you can trade the fourth seat for adding the tip fuel and getting another 400nm range.

Amazing how so many people simply refuse to see how amazingly efficient the Comanche is, just because it's old and they're blinded by shiny new plastic.

peterh337

9th Mar 2012, 21:20

There are actually a number of planes which can carry four people and enough fuel for 1000nm.

It depends on how heavy the four people are :)

In the 1950s, they may have averaged 70kg each (male) or 50kg (female). Today it will be more like 90kg for the males, 70kg for the females, and with very frequent "excursions" towards the 120kg mark (for either sex :) ). That makes a massive difference to the loading, obviously.

AdamFrisch

9th Mar 2012, 22:31

Well, you have to make special allowances for any Ed Swearingen or Ted Smith design;)

Old Akro

9th Mar 2012, 23:00

This is a pretty easy question. If you are flying to a station, then you need to carry stuff. So the rear door of the Cherokee six / Lance / Saratoga / Seneca II is invaluable. I've carried everything from car parts to coffee tables in ours. Can't do that in a 310 or Twin Comanche or Aerostar. The Seneca II has better loading flexibility than a Baron (only other twin with a rear door) and is cheaper in every regard. If you want to get above the bumps on a hot day, the Seneca will do that easily (unlike a loaded six). The SIDS programme makes any twin Cessna other than the T303 problematical in terms of both maintenance & resale. The Seneca II has good shortfield performance if you need it and (unlike the Comanche) parts are easy and relatively cheap. There is less labour in the 100 hourly's too. If you cruise it a Lance / Saratoga speeds (ie 45% / 55% power) the fuel burn increase is not much. At 8 - 10,000 ft I pretty much get 175 kts & 86 - 88 litres / hour. I moved to the twin after I did one too many outback flights at dusk. Once you've moved to a twin, there's no going back to a single.

englishal

10th Mar 2012, 07:15

Another important consideration is what the aeroplane looks like. I am not a big fan of aeroplanes that look like they should be in Back To The Future - you know when Marty goes back to the 50's. I'd rather have something looking modern and sleek. IMHO neither the Twin Com, Aztec, Baron or any of that ilk look particularly nice. Of course the Commander DOES look nice....but then I am biased towards them :)

Actually we're missing the "most economic twin". Isn't that the Cri Cri ;)

peterh337

10th Mar 2012, 07:27

Englishal has a huge point and that is basically why Cirrus are selling new planes for best part of $750k (no kidding) when you could get the same capability for $100k, chuck another $100k to sort it out and throw some avionics in, and the $550k saved will pay for more flying than most humans would be able to do in the rest of their lives.

I think some new piston prices are obscene, especially when a Jetprop in good condition can be had for $1M, will totally and comprehesively beat an SR22 into dust on every parameter (except the BRS, and perhaps the extra training before you can get insured), will more than beat an SR22 (and perhaps every piston aircraft) into dust on straight mission capability, and anybody with 750k will have 1M.

A DA42 is a nice civilised plane which appeals to "modern" passengers. It is just a huge shame that they trashed the whole deal with their engines and their way of treating customers. Every DA4x owner I know would not trust the company as far as he can throw them.

FlyingStone

10th Mar 2012, 08:27

Does anybody know what the P2006T service single-engine ceiling is in not-so-warm IMC (e.g. with carb heat on)?

peterh337

10th Mar 2012, 09:20

not-so-warm IMC (e.g. with carb heat on)

What is that?

Carb heat is not related to flying in IMC.

silverknapper

10th Mar 2012, 12:18

I guess Cirrus just marketed it well, and went for a market of non aviators by convincing them they could get a PPL and jump in their shiny new Cirrus for not much more than their Ferrari cost them.
I think some new piston prices are obscene, especially when a Jetprop in good condition can be had for $1M, will totally and comprehesively beat an SR22 into dust on every parameter (except the BRS, and perhaps the extra training before you can get insured), will more than beat an SR22 (and perhaps every piston aircraft) into dust on straight mission capability, and anybody with 750k will have 1M.

Agreed, and I know what I would have. However some people just like what they know, won't go the distances which keep turbines economical and are put off by the potential bills an old turboprop may bring compared with a brand new warrantied piston airplane. Also not everyone is capable of the transition, the good ones know this and stick with what they are comfortable with.

peterh337

10th Mar 2012, 14:03

One thing you can get in new planes is decent access, with a door each side.

The one-door designs which have tended to dominate the non-Cessna scene are awful.

The worst thing is a 6-seater with just one door.

Back in 2002, before I got the TB20, I looked at getting an old plane and throwing a lot of money at it. The thing I soon discovered is that such a project, done here in the UK, would be fraught with problems because there is so little expertise about. The options I was presented with would have involved parting with 5 digits but if you asked too many questions you would be asked to go elsewhere. This is not the USA... Today I would be able to manage a big refurb project, but not as a fresh post-PPL case. And I am sure that is true for most GA pilots. They are smart enough to know their limits and won't even try it. Until you have been in the ownership game for a few years, you don't have enough good contacts, and most other owners are of limited help because most buy a plane, run it down, and flog it...

BackPacker

10th Mar 2012, 14:06

Does anybody know what the P2006T service single-engine ceiling is in not-so-warm IMC (e.g. with carb heat on)?

Does the P2006T even have carb heat? I mean the traditional kind, where the air is heated by sending it through an exhaust muff, before it enters the carbs.

The Rotax 912S installations I know of either have no carb heat at all, or have heated carbs (using the engine coolant). With heated carbs, there is no performance loss so the usual configuration is "always on".

smarthawke

10th Mar 2012, 16:16

The P2006T does have carb heat and it is via hot air ducted off the exhaust muffler. Controlled by levers on the throttle quadrant.

In my experience, the P2006T (like most Rotax installations) suffers little from carb icing once the engine is up to operating temperature.

Heated carb systems are not certified. My own Rotax has Conair coolant jackets around the carb outlets so the carb body remains warm. Negligible power loss as it isn't hot air being fed to the engine, the warmth just prevents ice from forming.

BackPacker

10th Mar 2012, 16:53

Okay, so heated carbs not certified. I see.

the warmth just prevents ice from forming.

Actually what I understand is that the ice still forms (after all, the drop in temperature due to the venturi effect and evaporation of fuel is still there) but it cannot stick to the carb walls. So it either melts when it hits the walls, or is simply sucked as ice into the cylinders - where it evaporates real quickly...

However it's a very minor technical detail. The net effect is the same.

Rod1

10th Mar 2012, 18:08

I think what you need is an 11 seat Tecnam which runs on Mogas.

Aircraft P2012 Traveller - Costruzioni Aeronautiche Tecnam (http://www.tecnam.com/it-IT/flotta/Nuovi-Modelli/P2012-Traveller.aspx)

Rod1

Teddy Robinson

10th Mar 2012, 18:25

My vote would be for twin com .. believe lo-presti did some rather good go faster/less fuel mods ? .... that said there is another one well worth a look so long as all the AD's are done, I'm also unsure on the spares situation .. that is the Partenavia P68B /C.

Operated one in the 90's, very fuel efficient, great load carrying ability, good field performance, all round performance very similar to the Pa34, and good visibility, benign single engine characteristics, fixed spring leaf landing gear is also hard to break !! big drawback on a hot day was the cockpit became very warm if no sunshields were fitted, otherwise it was an absolute joy to fly.

The early AD's were to do with clumsy riveting of the firewalls after that pretty minor stuff..

bit more research it seems they are still being made, therefore spares support is available Vulcanair Aircraft - Fine Italian aircraft design and manufacturing in the general aviation business (http://www.vulcanair.com/page-view.php?pagename=AircraftP68C)