Chained incidents in LFMD (a twin Comanche down - possible fuel contamination)

WilliamF wrote:

It’s an interesting little dance with an empty 5L water bottle to check all 6 tanks in PA30 for water

But you only drain all tanks with the center drain valve below fuselage. So you just put the can below, sit relaxed in the cabin, pull the valve and change one tank after another. Where’s the dancing part in here?

UdoR wrote:

Let’s assume we’re talking about a 120 liter tank filled with 20 liter of fuel. So 100 liters of air may hold 5 ml of water in total. If we do this for, say, 10 days, we have 50 ml of water in the tank.

So in theory, water accumulation through condensation is possible. But on the other side, water accumulation in cars (where fuel tank is also vented) is no problem at all, and lots of cars are not babied at all.

So I do not think that condensation leads to any significant amounts of water accumulation. However, when an aircraft is left outside, draining sounds reasonable for several reasons.

50ml is not enough to stop an engine in liquid form , but there have been many instances where small amounts of water have frozen in fuel lines and caused engine stoppages. Especially with bladder tanks, where the water can accumulate behind ridges, and stay in liquid form, in the thermal inertia of the fuel until it is eventually sucked into the fuel system, at altitude, where the fuel lines are well below zero at which point it freezes. Hot humid ground conditions, bladder tanks, and climbs above the 0 degree isotherm are especially likely to cause this.

Pilot-H wrote:

but there have been many instances where small amounts of water have frozen in fuel lines and caused engine stoppages.

That sounds like an event that it would be particularly difficult to verify!

50ml is not enough to stop an engine in liquid form

I am sure it would. 50cc is a lot of liquid. At 12 USG/hr that is 12 seconds’ worth of fuel flow, and the engine deffo won’t run for 12 seconds, or even 1-2 seconds, if you feed it neat water. But perhaps it would not be neat water but some sort of mixture…

but there have been many instances where small amounts of water have frozen in fuel lines and caused engine stoppages. Especially with bladder tanks, where the water can accumulate behind ridges, and stay in liquid form, in the thermal inertia of the fuel until it is eventually sucked into the fuel system, at altitude, where the fuel lines are well below zero at which point it freezes. Hot humid ground conditions, bladder tanks, and climbs above the 0 degree isotherm are especially likely to cause this.

See e.g. here and, no, that question was never answered, and won’t be answered anytime soon.

UdoR wrote:

But you only drain all tanks with the center drain valve below fuselage. So you just put the can below, sit relaxed in the cabin, pull the valve and change one tank after another. Where’s the dancing part in here?

You could do it that way but…. When you do find water in one of the six tanks…. you now have no idea which tank it came from

Hence the more effective way is to watch the contents as it comes out with a second person helping, or get out each time and inspect each sample.

WilliamF wrote:

You could do it that way but…. When you do find water in one of the six tanks…. you now have no idea which tank it came from

If it is unusual to find water, you can do it from the cabin and only do the dance routine if you do find water…

Peter wrote:

50ml is not enough to stop an engine in liquid form

I am sure it would. 50cc is a lot of liquid. At 12 USG/hr that is 12 seconds’ worth of fuel flow, and the engine deffo won’t run for 12 seconds, or even 1-2 seconds, if you feed it neat water. But perhaps it would not be neat water but some sort of mixture…

All piston aircraft have a filter or gascolator that can hold 50cc of water at the bottom before it is fed to the engine.You would drain it during your next preflight. More than around 100cc and then it is fed to the engine.

Hello
I flew my Bonanza IFR to LFMD the 12/08/21 (2 CB rainy to be avoided before AMFOU and rainy in final 17).
I refuel my plan at 13:15 LT before parking.
Parked Mike stand 4 th position during 4 days and, since the the afternoon of arrival, very hot and dry weather

LFMD is COHOR airport till 31/08 due to biz jets arrivals and departures.
Departure Sunday 15/08 was planned
Ask to operations for a slot 0900 UTC the day before : no slot Sunday between 0600 and 1800 UTC….
See Notam and AVGAS fuel station closed from 12/8 to 17/08

Départ VFR (military zones all inactives…no war on Sunday !) via DGN MTL to south of Paris.

Contact Ground for Engine start : the man answer me « did you perform the preflight check ? »… surprised I say »heu…Yes » !? .. »did you performed the fuel purge ? »… »yes of course ! »…and the man said that there was 2 planes down and probably contamination.

I was confident but made a slow tawny and a long engine run…

Finally take off and flight was uneventful.

I forget to ask for the result of the fuel station check.

Philippe