I decided to set a fuel leak failure to see what would happen, out of curiosity. The centre tank was empty when I activated the leak with cross feed valve closed, so I was surprised to see fuel dropping at an even rate from both wing tanks.

 

Surely this would have to mean two separate leaks of the same severity occurring on both sides simultaneously?! This is obviously very unlikely; have I missed something or is this a failure that could do with amending? Perhaps there should be separate failures from leaks in the left/right/centre fuel systems?

Maybe the leak randomly chose a tank and it just happen to pick the center tank, have you tried it on another flight?

Maybe the leak randomly chose a tank and it just happen to pick the center tank, have you tried it on another flight?

 

No that's the whole point, the centre tank was already empty, I only had fuel in each wing tank. I was leaking from each tank at the same rate.

Over how long did you observe the fuel leak? Did you calculate the difference between expected and actual fuel? Was there ANY imbalance between tank 1 and 2?

 

The fuel leak in the NGX is very slow and not really noticeable for ~20-30 minutes. I tried it this evening and I calculated a fuel leak of 278 lbs (126 kgs) in tank 1 (left) after 40 minutes. I couldn't tell if the 63 lbs that weren't accounted for was the start of a tank 2 leak or there was some other explanation. Either way, a fuel leak in the NGX does create an imbalance without center tank fuel to compensate. Whether its from a single wing tank or both would probably require a longer test period.

 

Here are some images and my calculations from the test:

 

This is the control (no fuel leak)

 

 

This is the test with the fuel leak

 

 

Both these were conducted with the crossfeed valve closed.

Interesting, thanks Chris.

 

I was using accelerated time so I'm not sure what the duration was, but it was long enough for the leak to cause FMC predicted fuel at down route waypoints to gradually reduce as a result. Both tanks were, as previously mentioned, balanced at the end of the test. I had clear skies weather theme to eliminate wind fluctuations also.

 

More testing required to see if I can replicate you result I feel :Thinking:

Jordan,

I just found this in the NGX introduction pdf regarding the fuel leak failure:

 

"The location of a fuel leak will be random, requiring the crew to use the QRH procedure to identify and resolve the leak"

 

Sounds like could very well have been a leak on both wing tanks (the QRH does have a procedure for both tanks leaking at the same rate too).

Oooh, thanks very much!

 

I should have known PMDG wouldn't have overlooked such a thing.