Sorry - just saw my earlier post on page 4, so this is double post.
Do not know what happened to my lengthy response to OP's thoughts on the AC 685, but I'll try again. I'm a Twin Commander owner myself and love the aircrafts to bits. I now fly an old vintage 520, but am looking to step up to something more capable and the choices are 685 or Aerostar for me, both Ted Smith designs. However, one needs to know the shortcomings of the 685 and operate it within its parameters. I'm a longtime member in the Commander Group and have access to some of the brightest minds in regards to Aero Commanders and here's the nitty gritty on the 685:
PROS:
1. They have more range than any other twin engine piston. You can easily go
1500nm in them with their huge
327gal tanks. And as you know, range equals speed on long trips. Anywhere in the Continental US with a maximum of one stop.
2. They're also probably the quietest twin ever made because the engines sit far back, far out on the wing, are geared and have a huge ice shield protecting the cabin from ice.
3. The 685 is also cavernous inside and you can fit insane amounts of gear, luggage, people etc.
4. Rugged - these are essentially 690's with piston engines, so built tough.
5. De-iced and fully certified for known icing, none of that halfway stuff you find on all other twins.
CONS:
1. As mentioned, they're 690's with piston engines, so they're susceptible to almost all the SB's the 690 airframe has. This means a
36 month recurring spar inspection (unless you eliminate with costly STC), a 5 year teardown and inspection of the gear etc.
2. On top of this you have highly strung geared engines that they pull every inch of power out of. Now, I fly geared engines myself and the gearing is not the problem - that will last way beyond TBO if you fly them correctly (positive drive), but because they pull so much power from them you'll find that you'll probably have to swap some cylinders before TBO. O/H is expensive - plan on at least
$50K/engine.
3. Also, this is a big and heavy airframe and it will burn
45gals/hr doing 200kts, whereas an Aerostar will do
25gals/hr LOP doing the same. Just so you are aware. Sure, one can pull back and get down to 30-35gals/hr, but then you'll be traveling as fast as any of the smaller twins burning less.
4. Turbos are hard to come by new, but can still be overhauled.
5. Known for being rwy hoggers. The saying
"if you can see the end of the rwy, it's too short" was uttered about 685's. But if you're not at gross weight and not too high, they perform pretty good. Book says
2700ft takeoff at gross, but go-stop distance would have to be in excess of
4300ft.
6. All the other Commanders excel on grass and gravel, but this is probably the single model that doesn't. It's not that the landing gear or design can't take it, it just needs a bit too much rwy and sits a little too close to the ground and will get belly rash.
7. Not a mountain flying airplane. Lose an engine on takeoff at high DA, and you have your work cut out for you.
So, to summarise. It's not an airplane for anyone who isn't realistic about it. It's basically like having an underpowered turbine with slightly cheaper engines. It's an extreme long range cruiser made to fly in the flighlevels and never stop for gas, going between comfortable FBO's and long tarmac rwy's. It's not a bush plane like the other Commanders. But if you're fine with that, and if you can afford to keep them flying, then you have a wonderful, quiet businessliner on your hands.
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