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Author Topic: 680-FL to FL(P) Conversion  (Read 1933 times)

igm05270

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680-FL to FL(P) Conversion
« on: April 15, 2022, 02:13:01 pm »
I know that there wasn't many 680-FL(P)'s made from the factory and think that with the MR.RPM Conversion that a FLP would be a great aircraft. It looks as though there was no additional type certificate for the FLP vs. the FL. So paperwork wise I would think it wouldn't be too difficult.I am doing this as a thought experiment as to the complexity to do something like that and am worried less about the cost. And as a side note, anyone who has the piston powered commanders with the pressurization system, do you like it? Also, if anyone has a copy of the parts manual with the pressurization system that would be greatly appreciated as I am having a hard time finding the manufacturer of the pressurization system.

Adam Frisch

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Re: 680-FL to FL(P) Conversion
« Reply #1 on: April 15, 2022, 11:42:24 pm »
As I recall it, New York Air Machine was the producer of the compressor for pressurizing the cabin. Long gone and the parts are very hard to find, if you can at all. Plus I'm sure there must have been some structural reinforcements in the cabin to be able to handle the pressurization, so might not be as straightforward as it seems. Glenn, who started this forum, has an FLP, but I think he's given up on it.
Slumming it in the turboprop world - so you don't have to.

Big Pistons Forever

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Re: 680-FL to FL(P) Conversion
« Reply #2 on: April 16, 2022, 09:08:31 pm »
I think the Mr RPM conversion eliminated the hydraulic cabin air compressor and replaced it with a more modern turbo charger bleed air system.

It would seem to me that the this conversion is the only way this airplane is practicable as both the old geared engines and associated systems are becoming totally unsupported, but there doesn’t seem to be many still around.

I would suggest the easy way to get a pressurized piston Turbo Commander is to find a good 685. The engines have a bad rep but I think that is due to operator ignorance. I have a fair amount of GTSIO 520 time and the engines on the airplane did not need significantly more maintenance than the smaller direct drive turbo charged Continentals. The difference with the GTSIO is it will not tolerate poor operational procedures. Start with some good engines and operate them properly and you will have a good experience.

donv

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Re: 680-FL to FL(P) Conversion
« Reply #3 on: April 16, 2022, 09:22:47 pm »
I agree... if you want such a thing, the 685 is the only practical (and even that is stretching it) alternative.

On the other hand, if you want a 680FLP for non-practical reasons-- because it's cool or has sentimental value or is historic-- then I would find a real FLP and restore it. That will be much easier than trying to convert one, and I'm not sure that "conversion" is even possible-- I think the factory was just using the easiest and cheapest certification path.

JimC

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Re: 680-FL to FL(P) Conversion
« Reply #4 on: April 17, 2022, 05:58:02 pm »
Mr. RPM conversions were IO-720s...they don't have turbos to tap for bleed air.

The GTSIO-520s on the Commander are NOT the same as the ones on the Cessna 421. They have much more boost and a different (read: expensive and rare) fuel injection system.

421: 375 hp
685: 425 hp


Edit: wrong, wrong, wrong. I was wrong.

The IO-720s used are both the IO-720-B1B NA engines and the IO-720-B1BD turbocharged engines. According to Stars & Commanders, "When used in the pressurized models the hydraulically powered compressor system was replaced with a bleed air system from the turbochargers."
« Last Edit: April 18, 2022, 07:00:47 pm by JimC »
500B, B200

JimC

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Re: 680-FL to FL(P) Conversion
« Reply #5 on: April 18, 2022, 01:00:34 pm »
Posted the day after your first post:

https://www.barnstormers.com/classified-1508572-MRRPM-680FL(P)-non-pressurized.html?catid=22840

text:
MRRPM 680FL(P) NON-PRESSURIZED • $285,000 • ACCEPTING OFFERS • 12,500 TTAF, 900/100 on IO720 /400hp ENG.Very long range fuel, 2 camera ports.Winglets, Cleveland’s • Contact Paul Gendron - RPM COMMANDER, LLC , - located Deerfield Beach, FL 33441 United States • Telephone: 954-547-3002
500B, B200

donv

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Re: 680-FL to FL(P) Conversion
« Reply #6 on: April 18, 2022, 01:20:46 pm »
So that one apparently went the other way, from pressurized to non-pressurized.

JimC

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Re: 680-FL to FL(P) Conversion
« Reply #7 on: April 18, 2022, 03:48:32 pm »
Pressurization and camera ports don't mix - but maybe it can be returned to its original glory by someone with an infinite wallet.
500B, B200

donv

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Re: 680-FL to FL(P) Conversion
« Reply #8 on: April 18, 2022, 11:13:16 pm »
There are some airplanes with camera ports and pressurization-- I flew a 980 for a while with a camera door and normal pressurization.

However, these old systems probably would struggle with that... and I would guess this airplane is more valuable as a camera platform than as a traveling machine.

JimC

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Re: 680-FL to FL(P) Conversion
« Reply #9 on: April 19, 2022, 10:24:34 am »
Well, there ya go - I was wrong twice in one thread. Maybe I can go for the trifecta...?
500B, B200