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Fuel Leak

TXFlyGuy

Well Known Member
Large transport aircraft have provisions that allow a certain amount of fuel to leak, measured in drips per minute. When I was a Second Officer on the DC-10, I found fuel dripping from the engine nacelle area. When we contacted the mechanics, they pulled out the MEL and it stated that we were good to go with "X" drips per minute.

So now that my fuel tanks (6) are full of fuel, we have discovered a slow seepage from the left main tank. One drip each 15-20 seconds. It is seeping along a seam line on the inboard side of the wing (wet wing).

Is this an automatic grounding issue, completely unsafe to fly?

Or like in the case of the DC-10, are we good to go? My test pilot said it's not a no-go item.
 
Is there a reason to not drain the fuel and fix the leak before flying, assuming the airplane is at a location where this can be done?
 
Is there a reason to not drain the fuel and fix the leak before flying, assuming the airplane is at a location where this can be done?

It would require draining almost 40 gallons. Yes, we could do that.

There are two options...

1. Open up the inspection panels, and attempt to apply CS3204 Flamemaster Sealant. This was done before at the factory. Leak is still there.

2. Drill the rivets out, and completely drop the tank out of the wing. Then re-seal the whole tank.

This is the first time the tanks have been filled to max capacity.
 
I agree with your test pilot - that's a major leak and is a no-go item.

Jet A is much less volatile than 100LL, and much less likely to start a fire from vapors coming out of a small leak. That leak you have is not "small" and the avgas is much more volatile and will give off much more flammable vapor. That needs to be fixed.
 
Large transport aircraft have provisions that allow a certain amount of fuel to leak, measured in drips per minute. When I was a Second Officer on the DC-10, I found fuel dripping from the engine nacelle area. When we contacted the mechanics, they pulled out the MEL and it stated that we were good to go with "X" drips per minute.

So now that my fuel tanks (6) are full of fuel, we have discovered a slow seepage from the left main tank. One drip each 15-20 seconds. It is seeping along a seam line on the inboard side of the wing (wet wing).

Is this an automatic grounding issue, completely unsafe to fly?

Or like in the case of the DC-10, are we good to go? My test pilot said it's not a no-go item.

1 drip every 15-20 seconds is not seepage, it is a leak!
Seepage and even drip allowances are acceptable on larger turbine aircraft given the amount of fuel they hold and the many possible sources for leaks. Additionally the volatility of Jet A compared to gasoline is also a factor. Pull the tank and seal as necessary. I'm sure you won't have any problem finding someone to take your fuel.
 
This IS a No-Go situation.

PLEASE...Repair the leak before further flight!
 
my $.02 worth---if its dripping, whats to say that during flight loads it doesnt start leaking MORE and doesnt stop?

Tom
 
well, as usual the spirits of admonition are already on the loose, so I won’t spend more advice ;)

One thing though:
fuel dripping from the engine nacelle area
Well, I don’t have the DC-10 MEL at hand, but remember the leakage to be tolerated only from the fuel drain mast, below the nacelle. And not from an unknown location inside the cowlings...
 
So, you have good hangar & aircraft insurance?
Some friends jointly own a 9A & had a ‘slow leaker’ as they described it. One day after their flight they topped off the tank & went home. Next morning they arrived at the hangar to a very strong smell of gas & an EMPTY fuel tank. The sealant leak totally failed over night.
Good thing the furnace wasn’t lit that night.
 
What others have said - repair the leak before further flight.

In the airplane I fly for work, we also have the option of flying if the leak isn't "bad enough" and MX writes up an MEL for it. However, that's jet fuel - kerosene, essentially as you know - which isn't nearly as volatile as avgas. A match won't ignite a puddle of jet fuel, but it'll produce a show with avgas. Leaking jet fuel isn't nearly the hazard that leaking avgas is - not by a long shot.
 
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