Piper COMANCHE 260 User guide

the
LOBFRLLE ()
Owner’s
Handbook
N
Piper
Aircraft
Corporation,
Lock
Haven,
Pa.
U.S.
A.

Additional copies of this manual may be purchased
by writing to the SERVICE SPARES DIVISION,
PIPER AIRCRAFT CORPORATION, Lock Haven,
Pennsylvania, 17745, U.S.A.
Published By
PUBLICATIONS DEPARTMENT
Piper Aircraft Corporation
753 685
Issued: September 1964
Revised: January 1965
Revised: February 1966

Power Plant .
Performance .
Weights
Fuel .
Baggage
Dimensions .
Landing Gear
640901
SECTION |
SPECIFICATIONS

THE
PIPER
COMANCHE
SECTION
I
SPECIFICATIONS:
POWER
PLANT
PA-24-260
Engine
(Lycoming)
*0-540-E
or
**10-540-D
Rated
Horsepower
260
Rated Speed
(rpm)
2700
Bore
(inches)
5.125
Stroke
(inches)
4.375
Displacement
(cubic
inches)
541.5
Compression
Ratio
8.5:1
Dry
Weight
(pounds)
*397/%*402
PERFORMANCE
Take-off
Ground
Run
(ft.)
1090
Take-off
Ground
Run
(ft.)
(short
field)
660
Take-off
Run
over
50
ft.
barrier
1540
Best
Rate
of
Climb
Speed
(MPH)
110
Best
Rate
of
Climb
(ft.
per
min.)
1500
Best
Angle
of
Climb
Speed
(MPH)
85
Service
Ceiling
(ft.)
20,
600
Absolute
Ceiling
(ft.)
22,000
Top
Speed
(MPH)
195
Cruising
Speed
(75%
power
at
sea
level)
(MPH)
173
Optimum
Cruising
Speed
(75%
power
at
7000
ft,)
(MPH)
185
Optimum
Cruising
Speed
(65%
power
at
10800
ft.
(MPH)
178
Stalling
Speed
(flaps
extended)
(MPH)
61
Stalling
Speed
(flaps
retracted)
(MPH)
70
Landing
Ground
Roll
(ft.)
920
Landing
Ground
Roll
(short
field)
(ft.)
650
Landing
Distance
over
50
Ft.barrier
(ft.)
1420
Fuel
Consumption
(2400
RPM
75%
power)
(gph)
14.1
Fuel
Consumption
(2400
RPM
65%
power)
(gph)
12.7
650120
1

SECTION 1 THE PIPER COMANCHE
SPECIFICATIONS: (cont.)
PERFORMANCE
Cruising Range (75% power at 7000 ft.) ( mi.) 1120#
Cruising Range (65% power at 10, 800 ft.) (mi.) 1205#
Cruising Range (55% power at 15,400 ft.) (mi.) 1265#
# B6 gal. available fuel
Published figures are for Standard airplanes flown at gross
weight
under
standard
conditions
at
sea
level
unless
otherwise
stated.,
WEIGHTS
Gross Weight (lbs.) 2900
Empty Weight (Standard) (lbs.) 1700
USEFUL
LOAD
(Standard)
(lbs.)
1200
Empty Weight (Professional 422) (lbs.) 1793
USEFUL LOAD (Professional 422) (1bs.) 1107
FUEL
Fuel
Capacity
(gal.)
(Standard)
60
Fuel
Capacity
(gal.)
(With
Reserve)
90
Unuseable
Fuel
(Inboard
tanks
only)
4
Fuel Aviation Grade (Min. Octane) 91/96
04il
Capacity
(qts.)
12
BAGGAGE
Maximum Baggage (lbs.) 200
Baggage
Space
(cubic
ft.)
20
Baggage Door Size (in.) 20 x 20
2 640901

THE PIPER COMANCHE ) SECTION I
SPECIFICATIONS: {cont.)
DIMENSIONS
Wing Span (ft.) ~ 35.98
Wing Area (sq. ft.) 178
Length (ft.) 24.99
Height (ft.) 7.47
Wing Loading (lbs. per sq. ft.) 16.3
Power Loading (lbs. per HP) 11.15
Propeller Diameter (in.) .
LANDING GEAR
Wheel Base (ft.) 6.55
Wheel Tread (ft.) 9.66
Tire Pressure (psi) Nose 27
Main 42
Tire Size Nose (four ply rating) 600 x 6
Main (six ply rating) 600 x 6
660201 3

SECTION I THE PIPER COMANCHE
12'e"
4 640901

Engine and Propeller
Induction System.
Structures .
Landing Gear .
Control System
Fuel System
Electrical System
SECTION I
DESIGN INFORMATION
Heating and Ventilating System
Instrument Panel.
Vacuum System .
Baggage Compartment .
Seats .
Finish.
640901
.
. 10
10
.13
15
. 16
Y
.18
18
. 18

THE
PIPER
COMANCHE
SECTION
I
SECTION I
DESIGN INFORMATION
ENGINE AND PROPELLER
The
Comanche
260
is
powered
by
a
Lycoming
0-540-E,
carburetor
induction
engine
or
a
Lycoming
10-540-D,
fuel
injection
engine.
Both
engines
are
rated
at
260
HP
at
2700
RPM,
with
a
compression
ratio
of
8,5to
1
and
require91
/96
minlmum
octane
aviation
fuel.
The
six
cylinder,
direct
drive
engines
are
equipped
with
a
geared
starter,
12
volt
75
ampere
alternator,
carburetor
or
fuel
injector,
vacuum
pump,
dia-
phragm
fuel
pump
and
shielded
ignition
system.
Engine
mountis
of
steeltubing
construction
and
incorporate
vibration
absorbing
dynafocal
mounts.
The
allaluminum
engine
cowl,
is
a
cantilever
structure
attached
at
the
firewall.
Side
panels
are
hinged
for
quick
access
to
the
engine
compartment.
The
exhaust
system
consists
of
dual
exhaust
stacks
and
mufflers
with
the
exhaust
gases being
directed
over-board
at
the
bottom
rear
of
the
cowling,
on
each
side
of
the
nose
gear.
Heat
for the
cabin
interior
and
defrosting
is
taken
from
the
left
muffler
shroud.
An efficient
aluminum
oil
cooler
is mounted
on the
left
front
engine
baffle.
Engine
oil drainage
is accomplished
by
a
quick
drain
installed
in
the
right
side
of
the engine
sump.
The
propeller
on the
Comanche
is
a Hartzell
HC-
C2YK-1A/8467-7R
constant-
640901
S

SECTION II THE PIPER COMANCHE
speed, controllable unit, It is controlled entirely by use of the
propeller control located in the center of the lower instrument
panel.
INDUCTION SYSTEM
The Lycoming engine induction system in the Comanche is
equipped with a Marvel Schebler model MA-4-5 carburetor or
a Bendix RSA-5ADI fuel injector.
The carburetor installed on the O-540-E engine is of the
single barrel float type, and is equipped with a manual altitude
mixture control and an idle cut-off. Distributionof the fuel-air
mixture to eachcylinder isobtained by the center zone induction
system, which is integral with the oil sump and is submerged
in oil, insuring a more uniform vaporization of fuel. From
the riser the fuel-air mixture is distributed to each cylinder.
The fuel injector installedon the I0-540-D engine is based
on the principle of measuring air flow and using the air flow
signals to operate a servo valve. The accurately regulated
fuel pressure established by the servo valve, when applied
across a fuel control (jetting system), makes fuel flow pro-
portional to air flow.
Fuel pressure regulation, by means of the servo valve;
necessitates only a minimum fuel pressure drop through the
entire metering system. This makes it possible to maintain
metering pressure above vapor forming conditions, and at the
same time requires a fuel inlet pressure sufficiently low so
that a diaphragm pump can be used. An inherent feature of the
servo system is self-purging which eliminates any possibility
of vapor lock and associated problems of difficult starting.
The injection system components consists of a Servo Reg-
ulator which meters fuel flow in proportion to air flow to the
engine, giving proper fuel-air mixture at all engine speeds. A
Flow Divider receives the metered fuel and accurately divides
fuel flow to each cylinder Fuel Nozzle.
6 640901

THE PIPER COMANCHE SECTION 11
Installed in the instrument panel is a Fuel Flow Indicator.
This instrument is connected to the flow divider and monitors
fuel pressure. The instrument converts fuel pressure to an
accurate indication of fuel flow in gallons per hour, percentage
of cruise power, and proper leaned mixture for take-off at
various altitudes.
NOTE
An increasingor abnormally high fuel flow
indication is a possible symptom of re-
stricted injector lines or nozzles.
Induction air for either engine enters an opening inthe nose
cowl below the propeller and is picked up by a large air duct.
The air is directed through a filter and on to the carburetor or
servo regulator. For the fuel injection installation, located in
the air box at the throat of the servo regulator isa springloaded
door which opens automatically if the filter becomes blocked.
STRUCTURES
Structures are of sheet aluminum construction, and are
designed to ultimate load factors well in excess of normal re-
quirements. All components are completely zinc chromate
primed, exterior surfaces are coated with acrylic lacquer.
The main spars of the wings are joined with high strength
butt fittings in the center of the fuselage, making in effect a
continuous main spar. The spars are attached to the fuselage
at the side of the fuselage and in the center of the structure;
wings are also attached at the rear spar and at an auxiliary
front spar.
Wing airfoil sectionisa laminar flow type, NACA-64,A215,
modified, with minimum thickness about 40% aft of the leading
edge. This permits the main spar, located at the point of max-
660201 7

SECTION I THE PIPER COMANCHE
imum thickness, to pass through the cabin under the rear seat,
providingunobstructed cabin floor space ahead of the rear seat,
LANDING GEAR
The nose gear is steerable with the rudder pedals through
a 40 degree arc. During retraction of the gear the steering
mechanism is disconnected automatically to reduce rudder pedal
loads in flight. The nose gear is equipped with a hydraulic
shimmy dampener.
Retraction of the landing gear is accomplished through the
use of an electric motor and gear trainlocated under the floor-
boards, actuating push-pull cables to each of the gears. The
landing gear motor is activated by a selector switch located on
the instrurmnent panel.
To guard againstinadvertent movement of the landing gear
selector on the ground, a mechanical guard is positioned just
below the selector handle. The handle must also be pulled aft
before moving it upward. The gear selector is in the shape of
a wheel to differentiate it from the electric flap control knob,
which has an airfoil shape. As an added safety feature, the
warning horn is connected to the gear selector switch. The
horn will then operate if the
selector is moved to the "UP"
position with the master switch
on and the weight of the air-
plane is on the landing gear.
As a finalsafety factor to pre-
vent gear retraction on the
ground, an anti-retraction
switch is installed on the left
main gear. This prevents the
electric circuit to the landing
gear motor from being com-
pleted until the gear strutis
8 640901

THE PIPER COMANCHE SECTION II
fully extended. A green light
on the instrument panel below
the landing gear switch is the
indication that all gears are
downand locked. The warning
horn will also sound if the
power is reduced below ap-
proximately 12" of manifold
pressureand the gear has not EE: :r;-;c,
been lowered.
As optional equipment a o
visual indicator, located on & °i‘;§,.”,°:"
top of the instrument panel
which will pop-up if the gear is retracted and power is reduced
below 14" manifold pressure. This indicator is operated mech-
anically by the landing gear and throttle and therefore has no
connection with the electrical system.
The telescoping emergency gear handle should not be used
as the primary indication that the gear is down and locked. An
amber light above the switch indicates gears up. THE INDIC-
ATION LIGHTS ARE AUTOMATICALLY DIMMED WHEN THE
NAVIGATION LIGHTS ARE TURNED ON,
The brakes on the Comanche are actuated by toe brake
pedals mounted on the left set of rudder pedals and by a hand
lever protruding from under the instrument panel. Hydraulic
brake cylinders are located
above the left rudder pedals
and are accessible in the
cockpit for servicing. Park-
ing brake valves are incorp-
orated in each cylinder. Two
cables extending from the
parking brake "T" handle are
attached to the parking brake
valves. To prevent inadvert-
ent application of the parking
brake in flight, a safety lock
is incorporated in the valves
640901 9

SECTION I THE PIPER COMANCHE
thus eliminating the possibility of pulling out the "T*" handle
until pressure is applied by use of the toe brakes or the hand
lever.
CONTROL SYSTEM
The flight controls on the Comanche are the conventional
three control type operated by a control column and rudder
pedals. The all movable stabilator, with an anti-servo tab
which also acts as a longitudinal trim tab, provides extra stab-
ility and controllability with less size drag and weight.
Provision for directional and longitudinal trim is provided
by an adjustable trim mechanism for the rudder and stabilator.
Installed on the Comanche are electrically operated Max-
Lift flaps. ‘As the flaps are operated by an electric motor they
can be lowered and stopped in any desired position. The flap
control switch is located on the nose wheel well just above the
rudder trim control. Located on the instrument panel is a
flap position indicator which is marked to show the degrees of
flap travel. A range for take-off operation is also shown.
Located in the inboard end of the right flap is a lock which
holds the flap in the "UP" position so that it can be used as a
step for entry or exit. A second lock is incorporated to pre-
vent the flap from going fulldown in case a step load is applied
and the up lock is not fully engaged.
FUEL SYSTEM
The fuel for the Comanche is carried in two rubber-like
fuel cells located -in the inboard leading edge sections of the
wings. Capacity of these cells, which are classified as the
main fuel cells are 30 gallons each (28 gallons useable),
10 640901

SECTION I
THE PIPER COMANCHE
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640901

SECTION I THE PIPER COMANCHE
As optional equipment for the Comanche, a 30 gallon aux-
iliary fuel system is available. The system consists of two 15
gallon fuel cells installed in the wings just outboard of the main
fuel cells. Use auxiliary fuel in level flight only.
The cells should be kept full of fuel during storage of the
airplane to prevent accumulation of moisture and deterioration
of the cells. For long term storage without fuel, the cells
should be coated with light engine oil to keep the rubber from
drying out.
During normal operation the fuel is drawn to the engine
from the cells by a mechanically operated fuel pump located
on the engine accessory section. In the event the engine driven
fuel pump fails an electric auxiliary fuel pump is provided.
This pump is operated during starting, take-offs, and landings.
The fuel selector and strainer units for the system are located
between the front seats. Dailydraining of the strainer is accom-
plished in the cockpit by opening the hinged access door located
in the floorboard justaft of the fuel selector valveand moving the
quick drain valve handle to fullaft position. The general proced-
ure for drainingthe fuel systemis to openthe strainer quick drain
for a few seconds with the fuel cell selector on one cell, then
change fuel selector to the oppositecell and repeat the process.
The same process applies to the auxiliary fuel system. Allow
enough fuelto flowtoclear linesaswell asthe strainer. Positive
fuel flow ghut-off can be observed through the clearplastic tube
7 g 3 which carries fuel overboard.
Fuel quantity is indicated
{ by one electric gauge located
inthe instrument cluster. This
gauge will indicate the amount
of fuel in thecell that is se-
lected. An over-ride system
is incorporated so that it is
possible to check the amount
of fuelavailable inthe remain-
ing cells without moving the
selector handle to that cell
{ position. This is accom-
12 640901

THE PIPER COMANCHE SECTION II
plished by depressing the red button (located on the fuel selector
plate) under the desired fuel cell position. The fuel gauge will
indicate the amount of fuel available in that cell. When the red
button is released the indicating system will return to its nor-
mal operation.
When the fuel selector handle is not in a positive selector
detent position, more thanone fuel port will beopen at the same
time. Itshould be ascertained that the fuel selector is pos-
itioned in a detent, which can be easily felt when moving the
handle through its various positions.
ELECTRICAL SYSTEM
The Comanche electrical system includes 12 volt 75 amp
alternator, providing power at all engine speeds, a transis-
torized voltage regulator, an over voltage relayand a 35 ampere
hour battery. This advantage results in improved perform-
ance for radio and electrical equipment and longer battery life.
The battery and relays are mounted immediately aftof the
baggage compartment. Access for service or imspection is
obtained through a removable panel adjacent to the baggage
door.
Electrical switchesare located on the lower left side of the
instrument panel. The circuitbreakers, located below the clec-
trical switches, automatically break the electrical circuit ifan
overload should occur. To reset the circuit breakers simply
push in the reset button. It may be necessary to allow approx-
imately two minutes before resetting the breakers. Corrective
action should be taken in eventof continualcircuit breaker pop-
ping. It is possible tomanually trip the breakers by pullingout
on the reset button. The alternator circuit breaker, mounted
on the same panel, is of the switchtype and should not be open-
ed under any circumstances while the engine is running.
Standard electrical accessories, in addition to those al-
ready listed, include a geared starter, stall warning indicator,
640901 13

SECTION II THE PIPER COMANCHE
HEATING
&
VENTILATING
SYSTEM
PA-24-260
14 640901

THE PIPER COMANCHE SECTION 11
cigar lighter, ammeter and position lights. Glaze ban instru-
ment lighting and anti-collision light are offered as optional
accessories. Circuit provisions are made to handle optional
communications and navigational equipment.
Operation of the alternator system as far as visual indic-
ationto thepilot is the sameas for a standard generator system.
The ammeter, located in the upper right corner of the instru-
ment panel, will give a constant indication of battery charge
and/or discharge in case of a malfunction of the system. Should
a malfunction of the voltage regulator occur that would cause
a high voltage condition the over voltage relay will cut the
alternator out of the system. Battery power will still be avail-
able to the bus bar.
HEATING AND VENTILATING SYSTEM
There are four individual controls provided for regulating
the heating, defrosting and ventilating air. The controls are
located on the lower right side of the instrument panel in a
console panel.
Heated air for the cabin interior is provided by a heater
shroud attached to the left exhaust muffler. Fresh air is pick-
ed up at the air induction in- 5
let at the front of the cowl and
passed through the heater
shroud into a control valve
for distribution to the cabin.
Warmair for the defrost-
er systemisobtaineddirectly
from the heater shroud. The
amount of air applied to the
windshield is regulated with
the control in the console.
Caution should be used if itis
necessary to operate the de-
660201 15