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Author Topic: 680FLP  (Read 329 times)

donv

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680FLP
« on: February 02, 2025, 01:06:27 am »
I can't get over what a nice 680FLP this is... I'd like to know the serial number, as the registration number in the video is now on a Pipistrel...

https://youtu.be/9eZXPICDPcw?si=q8VlSMG1uK1D4bsb

Roy

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Re: 680FLP
« Reply #1 on: February 02, 2025, 08:49:07 pm »
Hmm... weird... Yes, N-number is a Pipistrel now, but previous registrations show TX and MT "homes" in 2006 and 2013, with 1477-5 as the serial #. And at 6:11 in the video they show the data plate as being 1477-5. So I'd imagine it is 1477-5?


donv

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Re: 680FLP
« Reply #2 on: February 02, 2025, 08:58:41 pm »
I was kind of fast forwarding through, so I missed the data plate-- thanks for pointing that out! I wonder what the tail number is now?

I was trying to find it on FlightAware, because it didn't seem to me like they were all that far from a ferry flight.

donv

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Re: 680FLP
« Reply #3 on: February 07, 2025, 01:01:24 am »
There is a new picture of it on Facebook doing a high speed taxi, along with some info from the actual buyer of the airplane (not the dorky youtuber)... looks like it might fly before long, if it hasn't already.

As I recall from reading about them on here, simply flying and actually making stuff like the pressurization work correctly are two different things.

Roy

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Re: 680FLP
« Reply #4 on: February 07, 2025, 02:29:49 pm »
Ask (or don't  ;)) Glenn how hard it is to keep everything working! His FP "project" as you recall turned him into a Beech 18 driver...

appleseed

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Re: 680FLP
« Reply #5 on: February 07, 2025, 04:06:38 pm »
I am highly skeptical of the whole operation. But, of course, I watch the every. bit of it. . Any content with 680 F, FL, P etc is irresistible.

As I remember the last video ended when fuel servo diaphragms were diagnosed kaput?

Did they document any progress?

I believe one of the reasons for the Mr RPM mod was to get rid of the cabin compressor and turbocharger bleed instead. Maybe this system will be more maintainable than Glenn’s.

donv

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Re: 680FLP
« Reply #6 on: February 08, 2025, 02:10:05 am »
I like the sound of getting rid of that whole hydraulic compressor contraption. Does it still use skydrol?

appleseed

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Re: 680FLP
« Reply #7 on: February 08, 2025, 01:54:52 pm »
Re: Skydrol. I wondered about that too. I always assumed that they did get rid of it, though now I can't remember that being mentioned in any of the Mr. RPM articles I've read. At a minimum you would have to overhaul every single hyd component with an o-ring in it.

Aside from the airplane, the best thing about this video is the knowledgeable old hand they bring in to oversee the actual work. He's cool. Just learning that the MR rpm conversions still use skydrol almost makes it worth sitting through all the hand waving and whitened teeth.

I did notice him (the old hand) slipping in a few falsehoods though. When he said that putting the gear handle in the up position would put the plane on it's belly even without hydraulic fluid or pressure... If he fooled you with that one it is time for a system review.

It made me go through my maint manual and ipc to try understand just where the cockpit guage, aux system check valve, and accumulator are in relation to each other.

Maybe the poh has a better schematic, but I couldn't find one that lays it all out. I did find a note that says the aux pump bypasses the accumulator. Lots of interesting details. Maybe not all needed to safely operate the plane. but fun to learn.

I hope they do another video. Would love to see them digging into the mysteries of the systems behind the baggage compartment. Also everything between the firewall and the back of the engine. It must be stuffed with turbos etc. Did they have to make new engine mounts, or does the 720 bolt right up to the igso mounts?

I would like to learn more too about the evolution from 680flp to the early 680 turboprops. Like the other early 60s turboprops, I bet it was a baby steps away from hydraulic cabin compressors, combustion heaters, skydrol etc.

donv

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Re: 680FLP
« Reply #8 on: February 08, 2025, 02:34:12 pm »
I hope they make another video as well! I really want to see it fly.

schrambow

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Re: 680FLP
« Reply #9 on: February 10, 2025, 12:13:49 pm »
The Mr. RPM we had didn't have the skydrol nor the hydraulic motor.  It used the bleed air off the turbo chargers for the pressurization- i am not sure if the bleed air ran the cabin supercharger or a different system.
I agree, a few falsehoods being talked about.  The gear handle in the up position when parked and no hydraulic pressure from the engine driven pumps, does not retract the gear.  But with the gear handle in the up position and as soon as you start the first engine, you should get a loud horn screaming at you for about 2 seconds, and will see the gear come up nicely as you will find your plane sitting on the belly of it within a few seconds later with the gear retracted-  this is not a nice feeling at all!
The Mr. RPM we had was a pretty heavy aircraft with a nice interior, etc... but did not climb very good on takeoff and in-cruise shook alot more than any other commander i have flown. Dick Mccoon went up with me a long time ago and put the plane in alternating single engine chandelles to try and figure it out the shaking.  His belief was that someone might have packed the wall of the fuselage with a ton of sound dampening material and didn't allow the tuning forks to do their work.  Fortunately, or unfortunately- depends how you look at it, we never got to dig into the shaking problem as i put the plane into a field south of the runway trying to take off at 230 pounds over gross with ice contamination on the top of the wing.  The landing/crash was too hard as it buckled the fuselage and one of the gears, etc...
It was a pretty airplane and if you got over the shaking, it performed decent at altitude in cruise, just glad i put it in a nice flat midwestern field, instead of a metro or mountainous area. It was a bad decision on my part to try and take off back then for sure and i got fined back then by the FAA too for the overgross takeoff, but, part of me still thinks i might have saved myself from a future mishap in poor terrain or saved the future buyer of that aircraft too.  Ah, that was 27 years ago now, just wow has time flied.
I still love our 680FLP- IGSO machine, just took it up yesterday for just a short flight,  it performs very good in our nice winters in the tundra here- summers, one has to really keep it lighter a bit for margins.  Its a fun airplane to fly and very quiet as well- loves to pull 47 inches on takeoff as it sounds so cool.  People on the group just love to see it takeoff as well, i get people always coming over later and taking about it.  Ground heat on this machine is actually better than the 980 also, as that heater in the 680FLP in a cold soaked plane just fires up and can get you really nice and warm very quickly, whereas in the 980, you have to run up the condition levers if you want any decent heat out on the ground.  I love them both!  This is an old picture i might have posted already, but they are so good looking, sorry.


 

schrambow

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Re: 680FLP
« Reply #10 on: February 10, 2025, 01:36:34 pm »
I am incorrect, I checked our old records, it was skyrol, however, the pressure was turned down to around 1000 psi, but it was skydrol yet, sorry on the incorrect information. I think the turbos put pressure to the cabin supercharger, but not 100 percent

donv

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Re: 680FLP
« Reply #11 on: February 10, 2025, 02:09:04 pm »
What a great pair of airplanes!

Does the pressurization on your 680FLP still function as designed?

schrambow

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Re: 680FLP
« Reply #12 on: February 10, 2025, 02:18:51 pm »
Yes, pressurization system works good.  i haven't been up to 17K feet with it lately, but last time i did,  we could get 3.0 to 3.1 differential with it.  I need to use it on a couple of hundred mile trip with it soon.  Everytime a trip comes up, the 980 is in the front of the hangar and easy to just grab that, and it seems like i am always in a rush to get from point A to point B.
I end up even speeding to my dentist appointments for no rime nor reason?  Just wish i could stop being in a rush for no reason, i think it's like a personality defect i have.
   

schrambow

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Re: 680FLP
« Reply #13 on: February 10, 2025, 02:27:04 pm »
I just replaced all 4 bungies on the main gear yesterday in the 680FLP as they were getting kind of brittle looking and old. It's kind of fun to do stuff like that, cut the old one out, take a punch and get the pin out and put the bungie on and use a 1/2 or 3/4 racket with extension drive to wrap around the other end of the bungie to the post. Not sure if i broke any FAR's, but it still was a simple fun task anyway for a Sunday afternoon.

donv

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Re: 680FLP
« Reply #14 on: February 10, 2025, 02:32:49 pm »
How many other 680FLPs (or 680FPs) are there out flying around?

It feels like not very many?