Problem with Grob-103

Early Twin-2’s had aerodynamic elevator trim (trim tab), but later models went with spring trim. The jumping back reminds me of a slipping trim bar where the desired trim position doesn’t hold its setting. Recommend you pull the front seat and see if there is any slipping of the desired trim position. Can’t remember exactly what the trim setup is on the Twin Two, but a look under the seat will reveal any malfunction.
Hope this helps,
JJ

Normal bias configuration. Springs attached pushrod.
Front spring fully fwd on pushrod, rear spring 110 mm
from the rear end of pushrod


t 18:02 11 February 2019,
wrote:
Early Twin-2=E2=80=99s had aerodynamic elevator
trim (trim tab), but later
=
models went with spring trim. The jumping back
reminds me of a slipping
tri=
m bar where the desired trim position
doesn=E2=80=99t hold its setting.
Rec=
ommend you pull the front seat and see if there is any
slipping of the
desi=
red trim position. Can=E2=80=99t remember exactly
what the trim setup is
on=
the Twin Two, but a look under the seat will reveal any
malfunction.
Hope this helps,
JJ

Maybe it's really a 2-33 in disguise...

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