News: Added Links For Twin Commander and Facebook Pages

Login  |  Register

Author Topic: A trip in my friends 681 - a pictorial.  (Read 10539 times)

Adam Frisch

  • Administrator
  • Hero Member
  • *****
  • Posts: 1656
    • Adam Frisch FSF
A trip in my friends 681 - a pictorial.
« on: October 19, 2015, 01:17:16 pm »
Hitched a ride with my friend Stan from Montgomery Field (KMYF) in San Diego to Stockton (KSCK) in his 1969 Turbo Commander 681. He was flying it up to have some maintenance performed by the Commander guru. It’s a great example of how useful and well performing even an second generation TP can be. It was a great trip to be along for, and a sunny smooth ride all the way. Here’s a pictorial.


Stan’s 1969 681 Commander basking in the sun at Montgomery Field, San Diego.


Here you can see the original Hamilton Standard props. Good news is they only need on condition overhauls. Bad news is they’re getting harder to find parts for when they do. Most people have switched to Hartzell. Stan found a good supply of parts and bought it all, so he’s set for his lifetime. The cheapest solution.


Nice old school panel in good shape. Mostly King stuff in there.


A King stack that’s soon needed to be updated to ADS-B, for the 2020 deadline. King being almost bankrupt and not innovating these days, he’s going to go with a L3 system for the ADS-B.


Older King GPS, but it works fine. Stan is a big fan of King, so he’s thinking of putting the new 770 in there.


Startup is automated. You wait for 15psi fuel pressure, and then just flick the switch and it does it all by itself. Temps go up to about 650 on start, but come down once it stabilized to about what you see here. A hot start starts at around 750 degrees (it depends on outside temp), so if it looks like it will speed past 700 on startup, it’s probably time to cut the fuel off. Here we can see the turbine temps as we taxi out. As you can see, fuel flows are always pretty high even at idle on TP’s. Here we’re burning 70 pounds, which is around 11gal/hr per side. Not too bad, but it certainly pays to minimize the time you spend on the ground. Good thing, no need for any run ups.


After a less than 2100ft ground run, we’re out over the Pacific and getting vectored up to our altitude. Then ATC gives us direct LAX VOR. Here we’re just south of LAX and about to cross right above it at 16000ft. I was literally looking at 747’s under us landing. The Class B airspace goes to 10000ft here, so you can cross VFR as well as long as you’re above that if you want.


Enroute at 16000ft by the coast. Unfortunately, my camera was the iPhone, so no global shutter goodness, instead the usual prop mess.


Here we can see the cruise FF. Stan likes to fly it at 540 degrees and the rpm pulled back to the bottom of the green arc (96%). We can see that the horsepower is around 400hp per side. Pretty frugal fuel flow of about 180 pounds per side, or 360 in total. That’s about 54gal/hr in total. With Jet A1 prices quite close to half that of Avgas here, it’s easy to see that they don’t cost more to run in fuel than a piston twin. On top of that you get better speed, so mileage is actually better. Here we were doing about 235-240 KTAS.


Stan is an anesthesiologist at a big hospital in San Diego. His father owned Commanders ever since he was a kid, so he learned to fly on them. He’s had this 681 for 12 years. Many consider the 681 to be the perfect TC for the private owner. By 1969 they had pretty much ironed out any of the problems with the first generation turbines. It’s a model with relatively few AD’s and a pretty simple aircraft.


Gear down and locked. Prepared for the landing at SCK. As you can see, Stan’s plane has the aftermarket winglets. It’s a useless device, only designed to make it look a little cooler. Apparently the story goes that Gulfstream, who by now owned Commander, knew very well that a winglet that’s less than 20% of the chord does nothing. But the CEO said “just make it high enough to fit the logo” and that was it. Notice the little pop out landing lights that fold out. They have a max deploy speed of 156kts, just like the gear!


Tucked away and waiting on her spar inspection. Stan has to do it every 36 months, but has chosen not to do the mod, as it's cheaper for him to do inspection for the remainder of his flying.

This trip was great for me, but also a bit sad in some other way. Nice to ride in a plane that’s very similar to the one I got. Stan’s plane is in great shape and is a stable and wonderful performer. I wish mine was as nice as his. The sad part was that once we landed I saw how little progress had been done on my steed since last time I visited.
« Last Edit: October 19, 2015, 01:36:10 pm by Adam Frisch »
Slumming it in the turboprop world - so you don't have to.

donv

  • Administrator
  • Hero Member
  • *****
  • Posts: 3220
Re: A trip in my friends 681 - a pictorial.
« Reply #1 on: October 20, 2015, 12:23:28 am »
That's a really nice looking 681! And a very nice panel. I imagine that was completely redone 10-15 years ago, from the looks of it.

Russell Legg

  • Jr. Member
  • **
  • Posts: 82
Re: A trip in my friends 681 - a pictorial.
« Reply #2 on: October 20, 2015, 06:34:32 am »
Great story Adam and nice pics - thx for sharing!
Stan's beautiful 681 has attended many of the Twin Commander Flight Group (TCFG) Flyins over the years and has always been a centrepiece of interest and conversation.

John Vormbaum

  • Newbie
  • *
  • Posts: 2
Re: A trip in my friends 681 - a pictorial.
« Reply #3 on: October 28, 2015, 03:48:32 am »
Adam, I have to point out that in the last picture, the 500B on the viewer's right in the background is mine...N353CC. Stan better not be cutting in line! I'm awaiting an annual!

/John

ghancock

  • Administrator
  • Hero Member
  • *****
  • Posts: 1152
Re: A trip in my friends 681 - a pictorial.
« Reply #4 on: October 28, 2015, 07:17:06 am »
I don't know, looking at the picture it looks like he's in front. :-)

--glenn
You can't win an argument with an ignorant person,  they'll just drag you down to their level and beat you with experience.

Adam Frisch

  • Administrator
  • Hero Member
  • *****
  • Posts: 1656
    • Adam Frisch FSF
Re: A trip in my friends 681 - a pictorial.
« Reply #5 on: October 28, 2015, 07:41:15 am »
John - everyone seems to cut in front of me! My plane has been there for a year already and still isn't done! :o
« Last Edit: October 28, 2015, 07:43:53 am by Adam Frisch »
Slumming it in the turboprop world - so you don't have to.

ghancock

  • Administrator
  • Hero Member
  • *****
  • Posts: 1152
Re: A trip in my friends 681 - a pictorial.
« Reply #6 on: October 28, 2015, 08:10:46 am »
Adam,

Isn't it funny how that works?  You'd think they'd focus and get everything done quickly as it's more money and a better customer in the long run.  But the reality is, they see it as not being done any time soon so why not do something else.  No matter how much you like the guys at the shop, eventually it just becomes a sore spot and you just want your plane back.

Luckily mine has only been in the shop for a bit over 3 months and I'm going Friday (I hope) to fly it for the first time.   The smaller shops have to spread their time out though to try to keep everyone happy, it just sucks it's always at our expense. :-)

Glenn
--glenn
You can't win an argument with an ignorant person,  they'll just drag you down to their level and beat you with experience.

Adam Frisch

  • Administrator
  • Hero Member
  • *****
  • Posts: 1656
    • Adam Frisch FSF
Re: A trip in my friends 681 - a pictorial.
« Reply #7 on: March 27, 2021, 09:20:33 pm »
Just spoke to Stan yesterday as he'd found some old 680V manuals when he was clearing out the hangar that he wanted to send to me.

But that wasn't the interesting part.

He'd taken his bird to Brian at Arkansas Turbine to figure out a problem he'd had with his power gauges. In any case, Brian had done a full Lebeau (sp?) test run and found out that they'd put the wrong NTS sensor on it as well as some sort of early temp sensor that was not kosher, making him run it in reality well below max temp. And like magic, he'd picked up another 120hp aside! That's huge! He used to cruise along at 240-245kts and now his 681 does 260kts all day long. Very cool.

Inspired by this I called Brian myself today and we've agree that when the time is right (i.e. the circumference of my wallet), I'll bring my bird to him and hope he can find another few horses in mine as well!

Hope springs eternal! ;D

But in all seriousness, if you can get 260kts out of a 681, that's not a far cry from a -5 powered ship. Actually makes them pretty competitive. Morris always said the 681 was the best airplane suited for the private owner, as it combined performance with low cost. I'm thinking maybe he wasn't wrong. At least not about that. ;)
« Last Edit: March 27, 2021, 09:24:39 pm by Adam Frisch »
Slumming it in the turboprop world - so you don't have to.

donv

  • Administrator
  • Hero Member
  • *****
  • Posts: 3220
Re: A trip in my friends 681 - a pictorial.
« Reply #8 on: March 27, 2021, 10:38:31 pm »
You basically have a 681 with your Century 680V, so all good!

I think Aero Air can do a Lebow-- maybe you should ask them?

Adam Frisch

  • Administrator
  • Hero Member
  • *****
  • Posts: 1656
    • Adam Frisch FSF
Re: A trip in my friends 681 - a pictorial.
« Reply #9 on: March 27, 2021, 11:59:38 pm »
You basically have a 681 with your Century 680V, so all good!

I think Aero Air can do a Lebow-- maybe you should ask them?

They're sick of me, Don. And I don't blame them. They just want the thing gone. And they couldn't find a used 3rd wheel with cycles on for a good price, so I think this is best done at smaller engine shop that has a lot of connections in the Ag world.

I'm coming up first half of April to get her, so maybe we can have a lunch or coffee?
Slumming it in the turboprop world - so you don't have to.

donv

  • Administrator
  • Hero Member
  • *****
  • Posts: 3220
Re: A trip in my friends 681 - a pictorial.
« Reply #10 on: March 28, 2021, 12:01:59 pm »
Absolutely-- just send me an email when your schedule is set.

donv

  • Administrator
  • Hero Member
  • *****
  • Posts: 3220
Re: A trip in my friends 681 - a pictorial.
« Reply #11 on: March 29, 2021, 01:02:03 am »
Is Stan's airplane a Century, or does it have the -43BL engines?

Adam Frisch

  • Administrator
  • Hero Member
  • *****
  • Posts: 1656
    • Adam Frisch FSF
Re: A trip in my friends 681 - a pictorial.
« Reply #12 on: March 29, 2021, 08:15:55 am »
Is Stan's airplane a Century, or does it have the -43BL engines?

It's a Century conversion, too. He's got the Hamilton Standards on his, which if I recall correctly are on condition only, so a pretty economical prop to run.
Slumming it in the turboprop world - so you don't have to.

Steve binnette

  • Hero Member
  • *****
  • Posts: 552
Re: A trip in my friends 681 - a pictorial.
« Reply #13 on: March 29, 2021, 02:35:11 pm »
What is a Lebow?

donv

  • Administrator
  • Hero Member
  • *****
  • Posts: 3220
Re: A trip in my friends 681 - a pictorial.
« Reply #14 on: March 29, 2021, 03:10:00 pm »
It is an engine test cell that they use to calibrate the engine instruments, particularly the torque sensors.

https://www.aviationpros.com/home/article/10389107/tpe331-strain-gage-torque-system

You take the engine off the airplane, mount it on the stand, and run it while taking all sorts of readings.

At least, that's my basic understanding at a very high level.

I know when my engines come off for hot section, I believe they run in them in the test cell before (and certainly) after. However, I think National Flight will do that testing, not Aero Air.