Engine Roughness - Piper CHEROKEE ARCHER II Pilot Operating Handbook

PIPER AIRCRAFT CORPORATION
PA.28-I8I,
CHEROKEE ARCHER
II
SECTION
3
EMERGENCY PROCEDURES
3.27
OPEN DOOR
The
crhin iloor on the
Cherokee is double latched. so the
chances
of
its springing open in
flieht
at
both the top and
side
are remote. However, should you forget the upper latch, or not
fully
engage
the
side
latch, the door
may spring
partially
open.
This
will uually
happen
at takeoff or soon afterward. A partially
open door
will
not affect normal
flight
characteristics,
and a normal landing can be made with the
door
open.
If
both
upper and side latches are open, the door
will trail slightly
open, and airspeed
will
be reduced
sliehtly.
To
close
the door
in
night, slow
the airplane
to
87 KIAS,
close
the cabin vents and open the storm
window.
If
the top latch is open, tatch
it. [f
the
side
latch is open, pull on the armrest while moving
the
latch handle
to
the latched position. If
both
latches
are
open, close
the
side
latch then the top latch.
3.2t CARBURETOR ICING
Under
certain moist atmospheric conditions at temperatures of
-5oC to
20oC,
it
is
possible
for
ice
to
form
in the induction
system,
even
in
summer weather.
This
is
due
to the high air velocity throu$h the carburetor
venturi and the absorption of
heat
from
this
air
by vaporization
of
the fuel.
To avoid this, carburetor
preheat is
provided to replace the heat lost by vaporization. Carburetor heat
should be
full on when carburetor
ice
is encountered. Adjust mixture
for
maximum
smoothness.
3.29
ENGINE ROUGHNESS
Engine roughness
is uzually due
to carburetor icing which is indicated by
a
drop in RPM,
and
may
be
accompanied
by
a
slight loss
of
airspeed
or al6tude.
If
too much ice
is
allowed to accumulate, restoration
of
full power may not
be
possible;
therefort, prompt action
is
required.
Turn carburetor heat on (See
Note).
RPM
will
decrease
slightly
and roughness
will
increase.
Wait
for
a
decrease
in
engine roughness
or
an increase
in
RPM, indicating ice removal.
If
no
change
in approximately
one
minute, refum the carburetor heat
to
"OFF."
If
the
engine
is still FUgh, a(iust the mixture for maximum
srnoothness.
The engine
will
run rough
if
too rich or too
lean.
The electric fuel pump should
be
switched
to "ON"
and the fuel selector switched
to
the other tank
to
see
if
fuel contamination is the
problem. Check the engine
gauges
for
abnormal readings.
If
any gauge rcadings are
abnormal, proceed accordingly. Move the magreto switch
to
"L"
then
to "R,"
then back
to "BOTH."
If
operafon is satisfactory on
either magneto, proceed on that magneto at reduced
power, with mixture
full "RICI{," to
a
landing at the first available airport.
If
roughness
persists, preparc
for
a
precaudonary landing at pilot's discretion.
NOTE
Partid
carburetor heat may be
wosc than no heat at all,
since
it
may melt part
of
the ice, which
will
refreeze
in
the intake system.
Whcn using carburetor heat, thorefore, always usc
full
heat,
and
when ice is removed
return the control to the
full cold position.
trsguED:
irnsr
lE,
1976
REYISED:
MAY23,l9t0
,
REFORT:
YF79o
$ll