Mart et al:
Having probably 800 hours in LS-6, I never had the flaps jump toward
negative when they were positive.
This will however happen in a flapped Schempp glider if you have
allowed the flap selector track to wear and not replaced it. It does
not happen if the track is as new. This happened to me on short final
in a N3. Don't panic, fly the glider, everything is fine. Replace the
track.
The best possibility I can think of for the LS-6 is that something
(certainly not winter clothing at Narromine, this time of year) was
pushing outward on the flap handle to prevent it from latching into
the ratchet track. Did the pilot in the story keep a water bottle or
any other supplies on the left side of the cockpit? Was he overweight
or overdressed? If so, that is likely the "POS" that some would,
having no experience in LS flapped ships, blame the glider for.
The one place I found the airbrake/flap interconnect in LS- 6 (LS-3
works the same) to be a problem was in wave. You can not use much
airbrake to prevent yourself from climbing above 17,999' or you'll go
over flap operating speed in a hurry. It becomes a legal problem,
which is usually preferred to a mechanical problem.
Jim