On several occasions now, after some time flying (40+ minutes) the engine has
had
a minor episode, like one mag has been turned off for half a second. It then
continues as normal (with me looking for a field). It seems unrelated to
temperature
or phase of flight, icing conditions, or turbulence, except perhaps
initiating a slow descent.
I have had a good think around the possible causes and why just these last few
months; one thing I did was change to using Essso Supreme (no ethanol) from
ordinary
Shell unleased; the other was to change the long filler tube to aluminium
(classic style).
Recently using the tank drain plugs I have noticed a small amount of water in
the
fuel (I'm not in the habit of checking this regularly as there was never an
issue).
So my current theory is, air is filling the long aluminium tube via the breather
and is trapped, when the temperature drops in the hangar condensation forms
on the inside of the tube and enters the fuel, either that or the Esso S+ garage
supplies it with water in.
It would fall into the starboard side of the tank but after 40 minutes or so the
fuel return to the bottom of the starboard side and roll/pitch changes may have
mixed the water and fuel sufficient that it is sucked into the port fuel line,
into the carb bowl and eventually into the engine at which point the mixture
refuses to burn for a beat or two. Once good fuel is back it carries on.
The old tube was rubber so this wouldn't have happened.
--------
Graeme Bird
G-UMPY - Mono Classic/XS FFW 912S, Woodcomp SR3000/3W CS, trutrak Gemini 2 axis
AP, PAW, PFLARM core, ads-b out, 8.33khz, mode S, FP-5, Aera500, SD on Nexus,
Smart A3
350 hours & 6 years on the Mono, 930 total
g@gdbmk.co.uk
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