SkyMaster Wing Mods

[John Hoffman]

Hooking up all 3 tanks must have started with the -G models, my 1973G is that way - no switching.

[Alfonso]

ROGER AND JOHN HOFFMAN:

Your news is a great news. Please could either of you email me or post here all the drawings and information on how the tanks are interconnected. I would like to see it, and I will consider installing or implementing it on my C336... it definitely is a safer operation. Please, you may email it to: fiestair@erols.com. Thanks a million and best regards, Alfonso.

[Ernie Martin]

Forget it, Alfonso. There is no STC and trying to adapt the design first implemented in 1973 on a different aircraft -- because the 336 and the 337 ARE different -- would be hugely expensive to be legal (i.e., after figuring out how to do it, it would require, as a minimum, engineering certification that the design is safe).

Your current design, on the other hand, is safe and effective (my '69 337D had it). Yes, it requires adhering to procedure, but it works fine if you understand the system and how to use it. That's what my Fuel Management page does at www.skymasterus.com.

Ernie

[stratobee]

Could someone summarize to a neophyte like myself which Skymaster versions had the simplest fuel management? Were the tanks interconncted from the -G model and simplified their use?

[edasmus]

It is my understanding that from 1973 and later (the G and H models) have the simplest fuel systems. Others please jump in here and either confirm or correct me as I am not positive.

My 1973 G model has the tanks in each wing all interconnected and under normal operations there is no fuel management. The right wing feeds the rear engine and the left wing feeds the front engine.

It is my personal procedure before engine start up to "exercise" the fuel selectors by rotating them throughout their full range of positions because otherwise they would never move. I also periodically cross-feed on the ground (right wing to front engine and left wing to rear engine) just to make sure the system works as designed and the engines continue to run in the cross-feed configuration.

The only other consideration with this fuel system is that because the tanks are interconnected with relatively small (though adequate) hoses, these models must be fueled SLOWLY!!! Most fuel pumps pump fuel much faster then the tanks can accept it. As a result the outboard most tank, which has the fuel port, fills quickly and gives the appearance that the system is full. IT WON'T BE! If you sit and watch for a few minutes, you can watch the level in the outer most tank dwindle down as the fuel gradually makes its way to the inboard tanks.

Ed

[Ernie Martin]

Good summary, Ed. I exercise the fuel selectors on the ground less often, maybe every 3 months, and have never found them frozen, provided you grease the mechanism at the wing root at each annual. And sometimes, on solo flights, I excercise them in flight, always near my destination airport, in case there is a problem.

Ernie

[WebMaster]

Jim Stack once commented that a new fuel selector was $1200.