Is there any indication to the crew of the aircraft about any potential leakage of fuel from any part of the plane?

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    $\begingroup$ There is a fuel gage that you should keep an eye on. $\endgroup$ Oct 30 '15 at 12:14
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    $\begingroup$ I recall that the flight computer on Airbus / Boeing computes the fuel quantity that should be using engine fuel flow. If the calculated fuel and actual fuel differs too much, it will show an amber alert. $\endgroup$
    – kevin
    Oct 30 '15 at 13:04
  • $\begingroup$ On every light aircraft I know of the fuel leak detectors are the pilots' eyes and nose. Fuel stinks, even a small leak can make things very unpleasant in the cockpit (trust me from first hand experience). A loose fuel cap can empty a tank in minutes due to suction, and that's visible to the pilot. Fuel dripping from the airplane is another visible clue. $\endgroup$
    – GdD
    Oct 30 '15 at 13:20
  • $\begingroup$ @GdD That's true in many cases, but at night or in IMC you probably won't be able to see fuel leaking. Of course your nose should still work :-) $\endgroup$
    – Pondlife
    Oct 30 '15 at 14:01
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    $\begingroup$ Gimly glider was not caused by fuel leakage. The cause was mistake between metric and imperical unit used. $\endgroup$
    – vasin1987
    Oct 31 '15 at 18:12

In a typical trainer aircraft (in this case, a C172), you have an annunciator panel that includes a "Low Fuel" light:


These lights only come on when fuel is low if the lights are functioning properly. This panel is located prominently, and is easy to notice. This is only one aircraft, but when you consider it is an entry level aircraft that is less sophisticated, it gives a baseline idea of what you could expect to see.

Also, there are fuel gauges displayed with all engine instruments that will indicate accordingly. While this isn't a leak detector, pilots are trained to monitor all instruments regularly and cross check the values - which is how a leak is identified in aircraft with low amounts of technology.

It is worth noting that checking the "LOW FUEL" annunciator is off is a regular checklist item that occurs before you start your actual flight.

As GdD mentions in the comments - you are taught not to rely on any one instrument indication, and panel lights are no exception.

  • 1
    $\begingroup$ What typical trainer are you talking about? I've been in 1 light aircraft which had a low fuel enunciator, and I was told not to depend on it! $\endgroup$
    – GdD
    Oct 30 '15 at 12:28
  • $\begingroup$ Gah - I put the aircraft type as part of the image description - I'll add it to the answer itself. $\endgroup$
    – Charlie
    Oct 30 '15 at 12:28
  • $\begingroup$ While this indicates you get short of fuel, this doesn't indicate if a leak is currently occurring. $\endgroup$
    – mins
    Oct 30 '15 at 12:31
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    $\begingroup$ Yes, but this information cannot help act before the tanks are low, which would be possible if a leak alarm existed. $\endgroup$
    – mins
    Oct 30 '15 at 12:39
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    $\begingroup$ I agree with @mins, this doesn't answer the question. $\endgroup$
    – GdD
    Oct 30 '15 at 13:08

There is no special indicator or warning about a fuel leak because it would be difficult to automatically detect a fuel leak with any certainty (fuel flow sensors are not super accurate, nor are fuel quantity sensors).

Pilots of small, single tank airplanes must rely on reading the fuel quantity indicators periodically and "knowing" how much fuel should be left and how much is actually left. Big discrepancies indicate a possible fuel leak.

Pilots of bigger, multi-tank airplanes check for (and, on more sophisticated airplanes, are warned about) fuel imbalances between tanks. A fuel imbalance again, indicates a fuel leak as it is very very unlikely that the same quantity has leaked from both tanks.

You can find further info about fuel leak detection on Airbus airplanes here.


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