Fuel Leak

[speedbird37]

Hi
I'm trying to find as much information as possible on fuel leaks!
Where did they occur (fuel lines, tanks,..)
when did they occur (ground, flight,..)
what were your consequences (fire, explosion, nothing, ..)
how the leaks were detected (visual, indications in cockpit,..)
how did the firebrigade deal with the fuel leak (e.g fuel leak on ground,...)
.........

Would be great if you can share your experience
Thanks

[411A]

Fuel leaks.
Small ones from fuel tank areas are normally detected visually, and are either deferred (allowable number of drops per minute), or fixed, depending on the situation.
Fuel leaks in engine feed pipes sometimes are not noticed until they become quite large.
Example.
Starting engine two (L1011) on the hard stand one day, large amounts of fuel were noticed just below the engine.
The engine was shut down, and engineers investigated.
The fuel feed pipe had split, so a change of part was ordered.
None in stock.
Pax offloaded and sent to hotac, the area was properly ventilated with large fans, and 'a small guy with very long arms' was sent up to TIG-weld the pipe, in situ.
Engine test run, no leaks, aircraft dispatched to destination.

[Piper19]

Have had several. Some I do remember for the moment:
- B727 fuel tank leak. Was visible by dripping at a drain mast. Inside the tank is a big black sack, called a bladder fuel tank. One of the connections between bladder and pipes were leaking. I had the opportunity (was the only person slim enough to fit into) to go into the manholes and thus inside the bladder. With special tooling of course and a mask, no metal tooling or equipment working on electricity. Also opened 2 manholes, one with a fan on it sucking fumes out, the other preventing to suck the tank vacuum.
Leaking was permitted to do 1 flight to the homebase I believe. (very cool to see grafitti on the inner tank walls "x was here"!!)

- B757 huge spill through the fuel tank vent (naca inlet) on the wingtips. Occured due to a malfunctioning shutoff valve. So during fueling the tanker just pumped in untill it came out of the vent. Huge spill, so firebrigade was called to clean.

- A300 engine fuel leak (out of drain masts) during engine working only. Was a loose supply pipe on the engine.

- Typical problem on several types: most modern pax aircraft engines have a small drain cannister on the engine, which collects fuel that is still in the supply pipe after shutdown. This collected fuel is normally used first during the next engine start. Sometimes the valve on this cannister is stuck or broken and when the cannister is full the fuel just goes through the drain mast. You'll see a puddle of fuel under the engine after shutdown, or see it leaking during engine crancking (even without fuel on). But not that serious to call firemen.

[vopz]

on modern airplane the features are very helpful .
fmc equiped airplane help a lot in recognising a fuel leak as some messages :

"USING RSV FUEL"
"INSUFFICIENT FUEL "
"CHECK FMC FUEL QUANTITY "

so we can have
-fuel IMBAL indication
- total fuel quantity decreasing at an abnormal rate
- excessive fuel flow

by exterior observation we can have
-fuel spray from strut or engine