Piper SENECA III - Propellers

PIPER
AIRCRAFT
CORPORATION
SECTION
7
PAT34-220T,
SENECA IH
DESCRIPTION & OPERATION
in
each
control
lever
locks
the
cowl
flap in
the
selected position.
To
operate
the
cowl
flaps,
depress
the lock
and
move
the
lever
toward
the
desired
setting.
Release
the
lock
after
initial
movement
and
continue
movement
of
the
lever.
The
control
will
stop
and
lock
into
place
at
the
next
setting. The
lock
must
be
depressed
for
each
selection
of
a new
cowl
flap
setting.
The
intermediate
lever
position is
used
for
climb
and
single engine operation.
The
full
open
position is
available when
abnormal
temperatures
are
encountered.
7.7
PROPELLERS
Counter-rotation
of
the
propellers
provides
balanced thrust
during
takeofT
and
climb
and
eliminates
the
"critical
engine"
factor
in
single engíne
flight.
Two-blade, constant
speed,
controllable
pitch and feathering Hartzell
propellers
are
installed
as
standard
equipment.
The
propellers
mount
directly
to
the
engine
crankshafts.
Pitch
is controlled
by
oil
and
nitrogen
pressure.
Oil
pressure
sends
a
propeller
toward
the
high
RPM
orunfeather
position;
nitrogen
pressure
sends
a
propeller
toward
the
low
RPM
or
feather
position
and
also
prevents
propeller
overspeeding.
The
recommended
nitrogen
pressure
to
be
used when
charging the
unit is
listed
on
placards
on
the
propeller
domes
and
inside the
spinners.
This
pressure
varies with
ambient
temperature
at
the
time
of
charging. Although dry
nitrogen
gas
is
recommended,
compressed
air
may
be
used
provided
it
contains
no
moisture.
For
more
detailed
instructions,
see
"Propeller
Service"
in
the
Handling
and
Service
Section
of
this
handbook.
Governors,
one
on
each
engine, supply
engine
oil
at
various
pressures
through
the
propeller
shafts
to
maintain
constant
RPM
settings.
A
governor
controls
engine
speed
by
varying
the
pitch of
the propeller
to
match
load
torque
to
engine
torque
in
response
to
changing
flight
conditions.
Each
propeller is
controlled
by
the propeller
control
levers
located
in
the
center
of the
power
control
quadrant.
Feathering
of
a
propeller
is
accom-
plished
by
moving the
control
fully
aft
through
the
low
RPM
detent,
into
the
"FEATHER"
position.
Feathering
takes
place
in
approximately
six
seconds.
Unfeathering is
accomplished
by
moving the propeller
control
forward
and
engaging
the
starter
until
the propeller
is windmilling.
An
optional
propeller
unfeathering
system
may
be
installed
which
consists
of
increased
capacity
governors, gas
charged
accumulators
and
a
latching
propeller
control
lever.
ISSUED:
JANUARY
8,
1981
REPORT:
VB-Ill0
REVISED:
APRIL 9,
1982
7-5