Engines run out because Trimm Tank

[AviationLife]

Hi, I have the problem that my engines are running out because the trim tank is not pumping the fuel back into the center tanks. I still had 4000kg in the trim tank, which would have easily been enough for the rest of the flight. But since I wasn't yet descending or landing, the plane didn't pump the fuel back and I ran out of engines at cruising altitude.
Xbox X User

[Sink-rate]

Hi,

do you remember your approx CG configuration? Was the aircraft in CRZ phase? The FWD transfer does not happen only in DES/APR phase. The FWD transfer should start once the aircraft get to CRZ altitude (few conditions have to be fulfilled for the FWD transfer).

Kind regards
Sink-rate

[AviationLife]

Sorry but where can I find this configuration in the MCDU? So I haven't set anything manually except my payload and fuel in the EFB.

[RicardoLVFR]

Bellow ZFW value its the ZFWCG value, which is the CG at the moment.

[RicardoVitor]

Sorry but where can I find this configuration in the MCDU? So I haven't set anything manually except my payload and fuel in the EFB.

Click on INIT in the FMGS and click on the Next Page using the directional arrows on the CDU "keyboard".

[AviationLife]

Hi,

do you remember your approx CG configuration? Was the aircraft in CRZ phase? The FWD transfer does not happen only in DES/APR phase. The FWD transfer should start once the aircraft get to CRZ altitude (few conditions have to be fulfilled for the FWD transfer).

Kind regards
Sink-rate

Unfortunately, I don't remember what CG value was entered. But if I recreate the flight and enter block fuel and payload exactly as I did last time, then the MCDU shows me a CG of 29.8. I assume that was the case last time too.
And yes, it was in CRZ

[Sink-rate]

This situation will be fixed in next update.

[AviationLife]

This situation will be fixed in next update.

Ok, thanks for this information. I'm curious to see how the A330 flies after the update. If the Avionic Update is implemented and more functions can be used in the MCDU such as Fix Info or the ability to add constraints to the waypoints, then it will be at the top of the list of my favorite aircraft. Keep it up…good work so far!

[Toddbro1979]

Forgive me If I am not correct, but it was to my understanding that the Center Tanks in the A330-900 were dry tanks. Meaning they were never used. Even with training on the A330-900, the fuel training only suggests inner and outer tanks. The trim from what was advised by tech friends with United- " they have the certifications - I do not." When they fuel and de-fuel a plane, the Fuel System Schematic. They advised that fuel in the center tank will cause instability issues and impact the MTOW for performance and of course to always save on fuel and maximize efficiency.
I was a little skeptical of this because sometimes my friends get annoyed by all my questions, I ask them and usually just to poke or make fun ... give me the business.
I did look into it a little deeper and I found this that could be helpful to understand what is happening behind the scenes while in flight.
https://www.youtube.com/watch?v=Og1DSen2NzI (this is on a A300-200) but more or less the same understanding.

Many airlines in the United States opt out on using the center tank, and it really should not effect the engine performance when the tank is empty. Perhaps for Xbox there is an issue. On PC, I have not experienced this effect.

I think the confusion is on later models it was not even an option. On the latest models through end of production in 2021, it was deemed as optional.

I hope this information helps.

Blue Skies

[RicardoLVFR]

On the A330-900 the center fuel tank is needed for long range missions.

Its the last tank that is refueled, meaning, that if the trip doesn't require the fuel, it won't be fueled.

The fuel capacity on the A330-900 is distributed according to the performance manuals and the FCOM for the A330-900. I think the center tank on the 339 is not optional, but standard, I might be wrong but that's the main selling point of the 339 and its range and performance.

Yes there are some A330's that don't have it, specifically some A330-300's older versions don't. That's why some of the early A330 models don't have that huge range that the A330-900 has. Later versions of the A330-300 do have that tank.