On Apr 29, 1:07*pm, "bds" wrote:
"Tony" wrote

wing tanks or header tank? *has there been any consistency in fuel
level during these events? ive had engine problems in airplanes with
header tanks at extreme nose up attitudes and low fuel levels. *your
"negative G" towpilot could be on to something. is there an engine
driven fuel pump on the pawnee, even with a header tank? *have you
checked to make sure it is working?

ive had a valve stick (on a cessna 150) and it was VERY noticeable,
not "very slight" roughness.

*********************

It has a header tank but the problem occurs regardless of fuel level. *If
anything, it is almost always full or at least half full when the problem
occurs.

I think part of the reason that the roughness isn't as bad on the 0-540 is
because you're losing 1 out of 6 instead of 1 out of 4 when a valve sticks.

Bruce

fair enough. does it happen only on tow or sometimes off tow too?
one towpilot mentioned negative G's as a possible trigger. I wouldn't
rule out fuel delivery issues. with a header tank, possibly coupled
with a weak or not working engine driven fuel pump (assumption), you
could have issues when a glider pilot starts to yank the tail up or if
your towpilots like to dive away after tow release.