I don't like to remove the instrument
since it can be a safety device while wave flying in anything less
then perfect weather.


In the US, the rule is pretty clear

*6.6.1 Each sailplane is prohibited from carrying any instrument
which:
* * * * * * * ** Permits flight without reference to the ground.

I'm not on the Rules Committee but it's arguable whether a T&B that's
disconnected from power (or the on-off switch) permits flight without
reference to the ground. I suspect the question would be how certain
could the CD be that the instrument couldn't be made operable after
it's inspected but before flight, whether normally or through
bypassing the connector/switch. There's probably a satisfactory way of
dealing with this involving sealing. What would trouble me is the
statement that "I don't like to remove the instrument since it can be
a safety device..." That would imply the pilot wants it available in
an emergency. Now we're back to past arguments about flap timers
(when, for a brief period, 15M gliders were allowed to fly in Standard
Class in the US with the flaps disabled or, if flaps only, a timer
permitting 5 min. of use for landing) and motorgliders (engines
operable but with a noise sensor in the flight recorder). Seems to me
that if the pilot could use the instrument in an emergency but with
loss of points, this would violate the letter and the spirit of the
Rules.

Chip Bearden
ASW 24 "JB"
USA