Aztec owners/pilots - cruise speeds and fuel flows?

[bradg33]

Pondering a 1973 E-model Aztec. What kind of cruise speed and fuel flows can one expect at say 8-9000? How's single-engine performance? Anything else I should know, other than "there are no cheap twins..." and "it's a flying moving truck?"

 

[Abram]

It has been a while, so I may be a little bit off, but I owned two Aztecs: A 1968 ish D Model and an early 1970s Turbo F.

If I recall, the D used to cruise around 155 to 160 kts on about 16 to 18 gals per side. The Turbo F cruised at around 165 to 170 but burned closer to 19 to 21 gallons per side.

They were both really great airplanes to fly and were stable traveling platforms. In addition, they really could carry a lot of stuff!

Abram Finkelstein,
N48KY

 

[mondtster]

I usually flight plan for 160 knots on 25gph. Seems to work well. The airplanes will haul a good load and do really well in ice, and also does well in short field and on grass. An Aztec is a very docile airplane, almost too easy to fly with regard to getting a multi engine rating in one.

The only real complaint I have with the airplane is with maintenance. These airplanes are fairly complex and will require some labor to keep them flying. Don't hire a lazy mechanic and don't buy a project airplane and expect to operate it on a shoestring budget or it will become apparent in short order. I've been working on getting a friends airplane into shape that was nice to start with but a lot of little stuff has cropped up as we've used it. I probably work on it about 3-4 hours for every hour flown right now, but hopefully that will go down eventually.

 

[bradg33]

I usually flight plan for 160 knots on 25gph. Seems to work well. The airplanes will haul a good load and do really well in ice, and also does well in short field and on grass. An Aztec is a very docile airplane, almost too easy to fly with regard to getting a multi engine rating in one.

The only real complaint I have with the airplane is with maintenance. These airplanes are fairly complex and will require some labor to keep them flying. Don't hire a lazy mechanic and don't buy a project airplane and expect to operate it on a shoestring budget or it will become apparent in short order. I've been working on getting a friends airplane into shape that was nice to start with but a lot of little stuff has cropped up as we've used it. I probably work on it about 3-4 hours for every hour flown right now, but hopefully that will go down eventually.

I'm not terrified of some airframe maintenance, but the engines concern me. Have you found the Lyc 540s in the Aztec to be pretty reliable? Given their size and only putting out 250hp, I'd think they'd be pretty solid.

 

[mondtster]

I'm not terrified of some airframe maintenance, but the engines concern me. Have you found the Lyc 540s in the Aztec to be pretty reliable? Given their size and only putting out 250hp, I'd think they'd be pretty solid.

The engines and props seem fine. It's just the little airframe bits and linkages that require some patience and massaging. For example, the gear is a simple hydraulic system but if one of the cylinders has an internal leak it can take several hours worth of methodical troubleshooting to determine where the problem is. I like the fuel system but there are a couple ADs that will need to be kept up on. Also, the heater has an AD and there are a few other airframe ADs that require recurring inspections and maintenance.

I like the Aztec. Yes it is a bit more draggy than a Baron is but it is far better suited to the type of flying my friend and I do.

 

[champ driver]

It's been so long since I flew an Aztec that I really can't remember the numbers anymore. The only one that seems to stick in my mind is 24-25gph, but I could be wrong.
I flew them for charter in the 80's and have maybe 600 hours in I think C or D models.
Ours had the Met Co tips with an extra 24 gallons per side, now that's some range, and we used to use it too.
I think they're stable and easy to fly, and a good IFR platform. With that fat Cub airfoil they'll carry more ice than something like a C-310, and not as critical on airspeed on short final.
They're never going to be as fast as a Baron or 310, or as sexy either, but if you want a truck that will carry almost anything you can stuff into it, then an Aztec will do it.

This is one of the ones I used to fly.

 

[GRG55]

Pondering a 1973 E-model Aztec. What kind of cruise speed and fuel flows can one expect at say 8-9000? How's single-engine performance? Anything else I should know, other than "there are no cheap twins..." and "it's a flying moving truck?"

My 1979 naturally aspirated 'F' trues out at 165 knots at 10,000 ft, burning 28 gph +/- 0.5 gph all in (taxi, climb, cruise, decent, taxi). In cruise if I dial back the engines to 2250 rpm (about 155kt TAS) I can get the fuel flow down to 11 gallons per side once properly leaned. I generally fly between 8,000 and 13,000 ft, more often on the high end of that range (my home airport is 4000 ASL).

Single engine performance is about as good as it gets for a non-turbo light twin - nothing spectacular, but in an Aztec it's a comparatively uneventful circumstance. With the exceptional useful load of the Aztec I tend to fly it light and get better than book single engine climb with that deliberate margin of safety. My airplane is used purely for personal transportation, combo family trips and getting out to the field locations to see staff and customers.

Here's a link to a thread from last January with various light twin operating costs:
https://www.pilotsofamerica.com/com...wning-and-operating-costs.89350/#post-1992219

The IO-540s are an excellent and reliable engine imo. But like anything if they've been neglected or haven't been treated with respect they can be a problem.

As much as I would like a pressurized, turbo-charged, high altitude rocket ship (a Beech Baron 56TC with the 380 hp Lycomings almost meets all these criteria ) , I find the Aztec is a wonderful plane for the flying I do and very decent value for the performance and load hauling capability.

Others have commented on the systems. The gear is pretty tough, and not prone to nose gear collapses and that sort of thing (unlike say the Seneca). There's nothing really complicated about any of the systems, including the hydraulic gear and flaps. However, if the airplane has been sitting for a long time these can get really expensive to rehabilitate. A higher time airplane that has been flown regularly is the better bet. The recurring ADs are mostly inspections on the later models like the E or F.

The Aztec is my first twin. I researched everything out there before deciding an Aztec was the right airplane for me. No regrets with that decision. (the Piper Twin Comanche was the runner-up).