Hello Folk,
The following is a series of raw conversations regarding TCFG members' thoughts/experience with flying/owning Model 500S & 685 Aero Commanders. These conversations are sourced from the TCFG Chatlist in the early 2000's and are strictly the opinions of members at the time.
While I am sure the experiences discussed are still as relevant in 2015, it should be noted that some key members featured have since passed out of Commander ownership.
Wing Commander Gordon will undoubtedly recall the times...
Enjoy!
Cheers
Russell
VH-CAU
560E s/n 726
500S vs 685
How about comments on the 500S vs. the 685. I've got quite a bit of experience with the geared Continentals and have managed to get them past TBO in the early days on a couple of 421s. I like the size of the 685. Any comments as to the pros/cons of the 685 over the 500S?
Those are two pretty different airplanes Bob. The 685 is certainly
the ultimate piston Commander in many respects - it is basicly a
690 Turbine with piston engines. I hope that Keith will jump in with
some further comments on the 685 as I think he has a lot of time in
them. The engines on the 685 are pushed about as hard as you can
possibly push a recip. They're making quite a bit more power than
the ones on a 421. I do know that they require very careful managment
in order to keep all the pieces located within their designed
distances from each other :-)
The 500S, of course, is a much smaller airframe, isn't pressurized,
and doesn't have the speed and altitude capabilities of the 685. It
will be much cheaper to own and operate. It will get in and out of
much shorter runways. The IO-540s are extremely reliable and can be
maintained by most any shop.
Guess it just comes down to what you want out of the airplane.
If you can afford the additional operational costs of the 685, it
is a outstanding x-country steed. I don't think you'll find anything
else that can provide the comfort and performance at that price.
Thanks for providing that text, Chris!
Bob Brown asks the difference between the 685 and 500-S. Per usual, I'm
going to drone on and on with a bit of history and opinion. This may torque
some people off. Forgive me, but I must.
The 685 was born when the Rockwell marketing department decided they were
missing a market segment that existed between the Shrike and the Turbo
Commander. In an effort to keep this niche -- and groom them for the 690 --
they decided to power the 690 airframe with piston engines.
The Continental GTSIO-520 (Sir Barry will provide the proper dash numbers, as
they changed during production and via Service Letter, ultimately ending in a
-K) was chosen and as Chris said, pushed to its maximum: 425 hp.
On the down side, you need to budget for 3 cylinders per year and if you
don't run through that many you're money ahead, if you exceed that, you're
not too far behind.
Next consideration is runway. As Morris Kernick says, "If you can see the
other end of the runway, it's too short for a 685." This is not a short
field airplane. It's an executive transport and for a trip from Wichita to
Dallas-Love, (seats full, long runways) it's the perfect airplane.
I squeezed the 685 in and out of 3800' strips in the Midwest, but they were
in cornfield country, zero obstacles, and I only did it when we were light on
a cool day and it was still ... sporting.
Performance: You need to get high to take advantage of the potential block
speeds. Below 12,000' figure 190-195 knots at 45 gph, 65%. Do not run lean
of peak EGT; rather, 75 to 125 degrees rich for exhaust system health.
Get up in the mid to high teens, you'll realize 200+ kts. On a warm day, its
climb rate is pathetic. On a cool day, it's OK. I seldom had legs long
enough to justify the climb to flight levels, but on occasion, did, and had
210 kts.
Bob Brown knows this, but for those of you who've never been responsible for
a pair of biggest Continentals, descent planning is an art.
ATC will assume you're a Turbo Commander and try to slam dunk you with the
rest of the turbine traffic at many airports. Don't let this happen; you
cannot afford to thermal shock the GTSIOs.
Now the good stuff. Who wouldn't want a stretched piston Commander with
Turbo Commander size and systems? Gadzooks! With 322 gallons of fuel, you
and your guest can fly way longer than your body can stand. Fly shorter legs
and fill the seats. Passengers love the cabin. This is a "Known Icing"
airplane, if you're doing hard IFR.
I've flown 4 different 685s and all made full cabin pressure -- as long as
the cruise RPMs were high enough at altitude.
It's quite possibly the quietest piston twin I've ever flown.
If you're bored with the stock market and Las Vegas, invest in a 685 and
if/when the Orenda engine installation gets STC'd, the value of the airframe
will zoom.
I think I've burned out most readers by now, so I'll stop. If you have any
questions, let 'em fly.
Chris kinda said it all. I think you might conceder a 680FLP as
you look at that size Commander. There are a couple out there with IO-720,
400HP Lyc installed and I think they must be the ultimate Commander.
A couple of thoughts. Does the 685 have the 36 month spar AD? I
think it does, and this would be a definite consideration! Also, Chris is
almost correct with the 690 comparison, it may be more closely related to a
980 or 1000 as I don't think it has picture windows?? Jb
A couple of thoughts. Does the 685 have the 36 month spar AD?
Yes, it does.
HI KIDS...........
We have been a little rough on the 685 this morning. It seems
that most airplanes are a compromise of some sort. The 685 is, as Keith
pointed out, a great ride for certain missions. When I sold my 560A and
bought a Duke years ago, it was not that the 560A was a bad airplane, my
mission changed. I needed an alweather interceptor that would stay at 13k on
one engine.
I got that performance with the Duke but gave up much in the process
(short field, operating cost, cabin load) The 685 is the perfect airplane
for someone who wants turbine room and good looks and needs the quite and
speed. If they live in the flat land on a long runway, what a deal!!
I guise what I am trying to say is that all Commanders are good, just
at different missions. Thoughts?? Jb
OK, after this, I promise to let the 685 thing rest ...
Proper engine installations data is:
2 Continental Model GTSIO-520-F or GTSIO-520-K Turbosupercharged engines. I
think at this point, all have been upgraded to -K.
The correct horsepower is 435, not 425 as I had said. Hey, it was early in
the morning ...
It's type certificate is 2A4, same as the AC-690.
And as far as fuel burn, I said 45 gph, which is about right at 65% cruise,
but plan on 50 gph for block fuel and you'll be very close to actual.
So. What shall we talk about next?
Keith S. Gordon
The 685 did indeed originally have the -F version of the Continental GTSIO-520. Under a retrofit program instigated by Rockwell, they were up-graded to -K at Rockwell's facility at Love Field, Dallas if I'm not mistaken.
But, am I hearing a different story to what I understood before? I've never heard a good work said about the 685, only that it was a bit of a dog. The engines being the problem of course, not the airframe.
I too was seriously looking at a 685 versus my 500B.
The other folks covered the high points, so I'll just add a few comments
since I was ready to purchase one. (basic conformations)
As Chris mentioned:
"Guess it just comes down to what you want out of the airplane"
Keith had some very strong points all across the board as well!
Just a couple of items that kept me from purchasing one.
1. The Mission:
I needed all wx, de-iced, cabin size (family of 6), adequate useful load
(wife packs the baggage compartment), etc. So far it sounds like a
perfect match right?
Right down the old commander line.
But high DA airports like TVL would not lend itself I'm sure to the 685
climb performance
during hot summer or icy winter days. I routinely fly to Tahoe, about 3
times a month.
I believe most 685's are typically based back east in the low lands.
(Nice one in WA for sale though)
2.
I needed the extra power/weight ratio to climb above the ice and during
those hot summer days.
Climbing out of Tahoe into moderate icing from 8K up to 18K is probably
not a wise decision in this airplane. (now I'm back to the 500B
restrictions but with much more maintenance costs)
The 500B has the extra long wings and it surprisingly climbs out very
nice from Tahoe,
even when the DA is around 9,000 ft).
Most of my trips to Tahoe in the winter takes me right into the ice, all
the way up to 18K.
Just from the climb performance numbers with this airplane (and morris's
comment), it started to look like a no-go decision on this purchase from
the very beginning.
The maintenance stories was the final decision maker.
3.
I routinely fly out of a 3200 ft airfield (RHV), Morris strongly stated
that you will need much more runway than that to be comfortable.
(otherwise close your eyes for the first 2000 foot climb)
4.
One other point that Morris brought to me my attention was the total time
on these airframes.
There are a couple of fantastic looking 685 airplanes out there for sale.
Notice the total time on them, there's a reason for that anomaly.
I just wanted more flying time than down time.
I have never canceled a flight in my 500B due to maintenance.
(Lots of wx issues yes, but no maintenance related problems)
Most Commander airplanes have high time on them, there are very few model
exceptions.
btw I was also looking into the 700. (Cabin is larger than a King Air)
Great airplane, numbers look good etc.
(At least this airplane has Lycoming engines (TIO-540-R2AD 340hp), man I
hope this doesn't start a nasty thread).
Positive note and previously said: a lot of airplane for the money, just
depends on your mission.
I think Keith brought out a good point when I talked to him about the 685.
The maintenance costs will run about the same as a 681/690, so why not
buy a turbine with good climb characteristics and performance.
I'm saving for this idea, hope the stocks go back up.
Randy
