Piper SENECA III - Page 291

PIPER
AIRCRAFT
CORPORATION
SECTION 9
PA-34-220T,
SENECA
III
SUPPLEMENT
5
CAUTION
The
"APPR"
mode
of operation will
continue
to
provide
airplane
commands and/or
control
without
a
valid
VOR/LOC
signal
(NAV flagin
view).
Also
erroneous
navigation
information
may
result
from COM
M
radio
interference
with
the
NAV
radio.
This
erroneous
infor-
mation
may cause
premature
APPR
captures
as
well
as
erroneous
steering
information.
Should this
occur
reselect
HDG mode
and then
reselect
APPR
mode.
(8)
Back Course Mode
(BC):
For BC
operation,
proceed
as
for
normal approach
mode,
but
engage
BC
mode
after selecting
APPR. The
BC
mode
reverses
the
signals
in
the
computer
and
cannot
be
engaged
without
a
LOC frequency
selected.
BC
status
is
indicated
on
the
annun-
ciator
panel. BC
mode
can
be
disengaged
by depressing
either
the BC,
APPR,
or
by
selecting
other
than
a
LOC frequency
on
the
NAV
receiver.
(9)
Vertical Mode
Switch
(Trim Up/Dn):
Operation
of the
vertical
trim switch
on
the Mode
Controller
provides
a
convenient
means
of adjusting
the
ALT
hold
or
PAH
angle
function
without
disengaging
the
mode.
ISSUED:
APRIL
21,
1981
REPORT:
VB-Il10
13
of
16,
9-44a