Hi! Franz/all.
I can confirm that Once in particular when parked overnight at ZelamZee in a
particularly violent down pour I emptied about half a litre of water from
one of my water drain taps .
Since then I have tried to ensure that the whole tank filler cap is blanked
off by tape especially the lock.
I do have a mop out access hole in the tank top and most winter grounding
periods I drain out and mop out to ensure both tanks are started with a
clean charge of fuel. I have also occasionally had small amounts of water
show depending on the level parking of the aircraft too.
Regards
Bob Harrison G-PTAG
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Frans Veldman
Sent: 23 June 2013 14:48
Subject: Re: Europa-List: tank vent and drain taps
--> <frans@privatepilots.nl>
On 06/23/2013 02:36 PM, Karl Heindl wrote:
> 1. What exactly is the reason again for having the tank vent in the
> airstream instead of a static position? Are we doing this because
> everybody else has always been doing it or is there a real safety
> aspect ?
I think it is the first. Especially when you have the tank vent connected to
the cobra, there is no risk of sucking the fuel out of the tank even if
there would be a negative pressure.
> I don't see the need for pressurization, especially since this must be
> miniscule, in a pump driven system.
In our soft tanks pressurization is even harmfull. It may cause the tank to
jam the aileron control, or abrasion of the tank when it repeatedly expands,
or other bad things. Best thing would be a neutral or slightly negative
pressure (the latter helping to keep fuel fumes out of the cockpit). Like
you said, we don't have gravity fuel feed like Cessna's but we are dependant
on a fuel pump anyway.
> 2. Why has no PFA/LAA or other inspector ever pointed out the fact
> that the drain tap arrangement is completely useless ? There would
> have to be an awful lot of water in the tank before any of it would
> show up in a drain cup.
I never got any drop of water out of these drains, and have never heard of
anyone else who got any water out of it.
(If anyone has, I would like to hear about it, and also whether this water
showed up in the gascolator as well).
Instead, I think the drains and associated plumbing are increasing the risk
of leaks, and are a hazard during an accident: if the gear is ripped off the
next thing to contact the ground and be ripped off are the fuel drains, and
together with the unavoidable sparks this will for sure trigger a fire. And
the drains can not be closed with the fuel valve so there is nothing you can
do about it.
The next time I will have maintenance on the fuel plumbing I will take the
drains out. It is just a matter of judging the safety advantages against the
safety disadvantages, and to my judgement the latter puts more weight in the
equation here.
The only things I found them useful for is for draining the entire tank for
maintenance and inspection (I have valves that can be locked in the open
position) and to fill the bottle of my camp stove. But all this can also be
accomplished by other methods.
Avoiding water in the tank can also be accomplished by refueling after each
flight so there is only little air left in the tank. Having said that, I was
surprised after the winter stop in an unheated barn with only a little fuel
in the tanks that despite all the temperature cycles (and associated
"breathing" of the tank) and our wet climate that no water at all condensed
in the tank, not a single drop!
Also, how is this arranged with cars? I have never seen a car with a fuel
drain, but yet water in the fuel seems to be unheard off (obvious causes of
forgetting to put the cap on the tank not counting). What's the story here?
> The obvious reason is
> the high point of the fuel exits and the high barb fitting on the taps
> themselves.
I have copper tubes inside the tank running to a position lower than the
fuel outlet for the engine. So in theory it could work.
Frans
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