I spent over 2.5 hours testing a fuel issue in the A330 and found that the problem does not appear to be just SimBrief planning or EFOB prediction. The aircraft’s actual fuel depletion does not match the displayed fuel flow.
Flight conditions:
-
Route: KSAN → PHNL
-
Aircraft: A330-200
-
Engines: Rolls-Royce Trent
-
Cruise configuration: clean
-
Gear up
-
Flaps 0
-
Spoilers retracted
-
APU not burning fuel
-
No time acceleration / sim rate used
-
Fuel units: pounds
-
Displayed ENG 1 and ENG 2 fuel flow were approximately equal
The displayed fuel flow was showing around 5,300–5,500 lb/hr per engine, so roughly 10,600–11,000 lb/hr total, which would be a believable cruise burn. However, timed fuel-quantity tests showed the aircraft was losing fuel at around 18,500–19,000 lb/hr total, about 68–72% higher than indicated.
Test 1: 10-minute total fuel check showing overburn
I started a 10-minute check with:
Starting FOB: 47,900 lb
After 10 minutes:
Ending FOB: 44,780 lb
Fuel used:
47,900 − 44,780 = 3,120 lb in 10 minutes
Expected burn at about 11,000 lb/hr total:
11,000 / 60 × 10 = ~1,833 lb
Actual vs expected:
3,120 / 1,833 = 1.70
So during this test, the aircraft burned about 70% more fuel than indicated.
This was the first clear sign that the issue was not just EFOB. The actual FOB was dropping much faster than the displayed fuel flow supported.
Test 2: Equal left/right fuel test
To isolate the issue, I balanced both sides to 15,000 lb each and ran a 10-minute test in normal configuration:
After 10 minutes:
-
Left side: 15,000 → 12,740
-
Right side: 15,000 → 14,100
Fuel used:
Expected total burn at about 11,000 lb/hr:
11,000 / 60 × 10 = ~1,833 lb
Actual vs expected:
3,160 / 1,833 = 1.72
So the aircraft burned about 72% more fuel than expected.
The important part is that the right side was basically correct. Expected per side was about 917 lb in 10 minutes, and the right side lost 900 lb.
The left side was abnormal. It lost 2,260 lb instead of about 917 lb.
Extra left-side loss:
2,260 − 917 = 1,343 lb extra
Total extra aircraft burn:
3,160 − 1,833 = 1,327 lb extra
Those numbers are almost identical, meaning the excess total fuel loss was almost completely explained by the abnormal left-side fuel loss.
Test 3: Left pumps off / crossfeed test
Next, I tested whether the left tank was passively leaking.
Configuration:
The left side stayed fixed at approximately 10,540 lb, so it does not appear to be a passive left tank leak.
Right side started at:
12,100 lb
After 5 minutes:
10,560 lb
Fuel used:
12,100 − 10,560 = 1,540 lb in 5 minutes
Expected burn if both engines together were actually using around 11,000 lb/hr:
11,000 / 60 × 5 = ~915 lb
Actual vs expected:
1,540 / 915 = 1.68
So even with the right side feeding both engines, the aircraft still burned about 68% more fuel than expected.
Findings
The issue appears to be that the displayed engine fuel flow is not consistently matching the aircraft’s actual fuel quantity depletion.
Repeated controlled tests showed actual fuel depletion around 1.68–1.72x the expected rate.
The right side / engine 2 side appears to behave normally by itself. In the equal-tank test, the right side lost 900 lb in 10 minutes, almost exactly matching the expected ~917 lb.
The left side / engine 1-associated fuel logic appears to cause hidden extra fuel loss. When the left pumps are on, the left side drains much faster than expected. When the left pumps are off and X FEED is open, the left tank stops decreasing, so it does not appear to be a passive left tank leak.
However, when the right side feeds both engines through crossfeed, the total burn is still about 68% higher than expected, which suggests the extra loss may be associated with engine 1 / the engine-1 fuel logic rather than a simple left tank leak.
Possible causes:
-
ENG 1 actual fuel consumption not matching displayed ENG 1 FF
-
the aircraft subtracting extra fuel from the ENG 1 / left-side feed logic
-
custom fuel system desync
-
fuel quantity, fuel used, EFOB, and displayed FF using different internal variables
-
crossfeed/pump logic interacting incorrectly with the fuel model
This makes a route like KSAN–PHNL very difficult to operate realistically in the A330-200 RR, because if the aircraft is consuming around 1.7x the expected fuel, normal SimBrief fuel planning becomes unreliable. Carrying enough extra fuel to compensate for a 68–72% overburn would be unrealistic and may exceed practical fuel capacity or takeoff weight limits.
This does not seem to be caused by:
-
APU fuel burn
-
aircraft drag configuration
-
time acceleration
-
a simple SimBrief fuel factor issue
-
or a passive left tank leak
Bottom line: under these conditions, the A330-200 RR’s actual fuel quantity depletion appeared to become around 68–72% higher than the displayed fuel flow indicated. The issue seems tied to the engine 1 / left-side fuel logic, and it makes realistic long-haul operation unreliable.
