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Fuel management on a plane with a complex fuel system - how is it done?

I’ve just read an article about a Baron 58 which crashed due to both engines stopping just a few miles out on an IAP. The pilot restarted one but failed to prevent the speed falling below Vmca, and rolled over.

He had a fuel totaliser but the fuel system, with the separate tip tanks, was clearly one which is difficult to operate in conjunction with a fuel totaliser unless you run the tip tanks dry during flight, which implies an engine stoppage (or coughing, at least) and I bet most pilots don’t want to do that.

Administrator
Shoreham EGKA, United Kingdom

I’ve never been bothered about running a tank dry in airplanes with multiple selectable fuel tanks (Cessna, Maule, Jodel etc.). What’s the problem?

In the case of the loathsome Jodel Mousquetaire, with its low wing and pathetic endurance, I run the front tank down to about 20 litres before emptying the rear reservoir; then remember that the tail will be lighter than usual when landing.

In a proper airplane with high wing tanks, one just has to be careful not to side-slip the wrong way when operating on one nearly empty tank.

Glenswinton, SW Scotland, United Kingdom

unless you run the tip tanks dry during flight

On the BE58, in contrast to Cessna twins with tip tanks as the mains, all tanks are interconnected and the fuel selector is just Left or Right for each engine (the opposite tank selection being run on cross feed) so you don’t run any tank dry per se, unless you are out of fuel. I believe this accident the pilot did not re set the fuel totaliser correctly and being a puddle jumper system, the fuel totaliser is prone to human error (modern turbine equipment will have mass related automatic fuel totalisers).

Running a tank dry on a pressure based fuel injection system with return lines to the fuel system, for example as found in Beechcraft and Cessna, I believe is not standard practice as you can get an air lock in the system.

The Cessna twins are notoriously complex, with up to six fuel tanks, nine fuel pumps (including engine driven, auxiliary, transfer, heater), some of the fuel pumps having two pressures depending whether it is being used to purge or prime, or replace a failed engine pump. The return fuel line returns fuel to the main tip tanks, so you need to run down the mains before using the aux or engine nacelle tanks. A typical fuel plan log on a Cessna twin would make a Boeing Stratocruiser flight engineer proud.

Last Edited by RobertL18C at 13 Feb 17:12
Oxford (EGTK)

Peter wrote:

I’ve just read an article about a Baron 58 which crashed due to both engines stopping just a few miles out on an IAP. The pilot restarted one but failed to prevent the speed falling below Vmca, and rolled over.

Yes, but in this case the complexity of the fuel system was not the main issue. The pilot simply didn’t take enough fuel, AND mismanaged the totalizer. (We read the same report).

The Q still stands though… How does one use a fuel totaliser in conjunction with a system involving multiple separate tanks?

Administrator
Shoreham EGKA, United Kingdom

Just run the aux tank(s) dry, then what’s left on the totalisificationiser is in the main tank(s).

Glenswinton, SW Scotland, United Kingdom

@Jacko in some systems you just pumped half the Aux tank overboard, in the Cessna you can see it coming out of the sniffle vent on the main tip tanks.

Basically read up on your type’s systems is the universal lesson

Oxford (EGTK)

I’m not sure what part of “_run_ aux tanks dry” can be interpreted as “_pump_ fuel overboard”.

However, if we really think any EuroGA reader might be daft enough to pump fuel from an aux tank into a main or header tank which is already full (in the case of aircraft whose fuel systems are thus configured) then yes, that would be a violation of Rule 1: “pay attention to the laws of physics”.

One may get away with breaking or bending all sorts of other rules, but that one does tend to bite back.

Glenswinton, SW Scotland, United Kingdom

Probably a reference to fuel systems where the return line from the engine goes to only one and the same tank, regardless of which tank is selected.

In an old V Bonanza, it is tempting to use the Aux tanks immediately after levelling off as they are intended for level flight only. If you do that shortly after take-off, the left main (wing) tank will quickly overflow from the fuel returned from the engine. You need to make room in the main tank first.

Biggin Hill

The old barons, have four tanks, two a side that are separate. I flew one for a while (without a totaliser) the gauges also might even manually selectable. Later on they just joined the two tanks, and even later they added a third all interconnected on each side. I vaguely recall that the return line is only to the corresponding main. The aux is behind the wind chord and the main in the front IIRC, In the older barons it is not hard to move the CG beyond the aft limit. Then you also need to understand the cross feed system correctly. The lesson being you need to know the system, many traps indeed.

Difficult to operate like that if your not doing it regularly or its your own plane so you can have confidence on the consumption rate (i.e. tested it). If your paying attention you will notice the pressure drop and can switch before the passengers or in my case parcels noticed

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