Brian and Gilles,
Great discussion topic.
I had a bit of a problem in 12AY. I was normally asphyxiated by 5000 feet
on a climb out by exhaust smell.
I foolishly placed my NACA duct about half way up the port side.
The exhaust from my stack on the 914 followed the prop wash and wing up-wash
right into the duct. NASTY. OK in cruise, but went directly into the vent
on climb out.
Moved to the Ultimate Ventilators in the windscreen and have been problem
free.
Exhaust/CO caused me to seal the NACA, wing fillet on the port side tightly,
and of course the firewall.
Firewall seals were easy using RTV or silicone sealant. Rudders were not
the problem. Grease the tubes and then RTV the small gap. Wait till dry
and move the rudders and it was done.
Mono's are a particular problem. Bellows work well to seal the rudder cable
holes. Our flat firewall has much smaller cable holes and can be sealed by
riveting on a piece of Red silicone cowl seal and make a slit in it. Not
perfect but simple and effective... The mono tends to allow air into the
cockpit through the handles. Tough to seal, but for winter comfort,
necessary.
Fuel smell haunted me for the first year or so.
I got rid of the rubber fuel inlet hose, and more importantly sealed the
fuel tank to filler neck with just a bit of ProSeal.
The fuel sender gasket would smell of fuel and leak when filled to the neck
just a bit. Again, proper sealing fixed that.
Changing to R14 or proper VOC compliant fuel line took care of that
lingering smell caused by the ethanol car fuel and additives.
Pitty no one I know produces a braded fuel hose which is ethanol fuel smell
(VOC) compliant for the mono tunnel.
Teflon hose works, but gets brittle and cracks. Nothing is perfect.
Common fuel smell/ leaks:
Overflowing carb float bowls which were not tested properly.
Improperly seated carb bowls.
Drain lines venting into the mono hole which goes directly to the cockpit it
seams.
Fuel tank fittings over or under tightened.
Fuel tank sender gaskets.
Fuel tank inlet hose and vent line leaks.
Sealing techniques for the CO:
Exhaust leaks in the 912S on the XS exhaust muffler are terrible. I am
trying a high temp sealant for the ball joints in the muffler to pipe
connection. We'll know more in a couple weeks.
(Look for soot which is brown streaks running up the exhaust pipes. Often
these jets of gas are directly hitting the carbs.)
Exhaust pipe to head seals leaking. (Use lapping compound and rotate the
pipe side to side until a seal is achieved at the proper pipe angle.)
The 914 exhaust seems trouble free.
Exhaust muffler pipe cowl exit placement can't be changed much, but the
longer the pipe the better it seems.
Keep air vents far forward, and near the door flange line to prevent port
side exhaust smell from entering the vent.
On the mono, try to seal up the firewall and keep the drains well off to the
side of the cowl exit near the foot well.
Seal cockpit holes through the firewall and mono tunnel lever gaps with
silicone or similar to seal your tunnel from the cockpit.
Wing gap seals need to be filled as well as possible. I use a window/door
tape type seal that has a rubber coating and compresses well to seal the
gap.
With all the above, finally have no fuel/exhaust smells or CO problems.
Regards,
Bud Yerly
-----Original Message-----
From: GTH
Sent: Wednesday, May 13, 2015 11:35 AM
Subject: Re: Europa-List: Smell of petrol in the cocpit just after takeoff
Le 13/05/2015 11:46, Brian Davies a crit :
> <brian.davies@clara.co.uk>
>
>
> The trouble with measuring CO with a digital sensor is that once you know
> the reading you feel you should do something about it, even if it is
> within
> limits.
Hi Brian,
So true^^!
Also the higher the number of parameters measured, the higher the amount
of head scratching...
Best regards
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