Piper PA-24 Comanche Service Manual page 296

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PIPER COMANCHE SERVICE MANUAL
SECTION VII
POWER PLANT PA·24-180
7.1. IncroduC'l:ioD. This section coven
power
plants
IdCd in die PA·24-180 and is comprised of instt\u:tions
for the removll. minor repair. scmceud installation of the
mPDC
cowliJll,
propeUer. propeUer,overnor,
engine. enpne shock mounts. induction SYStem, ipition system and lubrication system.
7·2. Description. The
PA·24-180
is powered
by
a Avco·LYc:ominl
Q.J60-A
four cylinder carburetor
induction. direct drive. Wet sump..horUontaUy opposed
air~ooled
eaaine with a compression ratio (If 8.5: 1
rated at 180
HP at
2100
RPM and
designed
to
operate on
91/96
(milWnum) OCQIle aviation p c fuel.
CowlinJ :;ompletely encloses the capRe aad
COlllila
of an upper and lower section. Side panels lift up
to allow access to the enpne.
The propeller may
be
a
constant
speed
McCauley or HlftzcU unit: controllecl by a ,overnor mounted
on
the eft(inc supplyin, oil throu,h the propeUcr shaft at various praSllfCS.
Oil
prasure from the govCtnor
moves the blades into high pitch (reduced R.PM) and cmaifupJ
twistinl
moment of the blades tend to
move them intO low pitch (hilh R.PM) in the absence of aowmor oil preuurc.
The induction system consists of a
wet type
air f1lter on the catly models
or a
dry type air filter on the
later models
and
a MA+5 MaJvel·Schebler c:ari)umor. This cqine is normally upir&ted with no
restrictions on maximum power output.
Bendix Scintilla
S~LN·20
series and S4DI·200
series
mapetos
arc
installed with their usoc:iated
components. The S4LS·20 series mqneto incorporate a
sinl1c
breaker and an impulse COUpliDJ inst&1led on
tile left masneto. The S4L.'1·200 series
rnapctO
synem
c:olllisa
of a sm,le contaet mapero on the right
Side of the engine and a dull contaCt mllncco on the left to obtain the
reurd spark necessary for narting.
A
starting vibrator. magnetO switcha and starter switch complete the system.
In addition to the previously mentioned componcnu, each eDJine is furnished with
:&
12-yolt statter,
H·ampere or 50-ampere 12'Yolt generator, vacuum pump
drive
and fuel pump.
The lubrication system is of the pressure Wet sump type. The oil pump which
is
located in the
ICCessory housing. draws oil rhroueh a drilled pusap leadinJ from the oil suction screen located in the
sump. The oil from the pump then enten
a drilled pusqe in the accessory housing. which feeds the oil to a
threaded connection on the rear face of the
ac:c:euory
housm"
where a
flexible line leads the oil to the
external oil cooler. Pressure oil from the cooler
returns
to
:&
second threaded coMec:cion on the accessory
housing from which point a drilled pUlale c:onducu oU to the oil pressure screen or filter. In the event that
cold oil or
an
obstruction should restrict the oil flow to the cooler.
an
oil by-pass valve is provided to pass
the oil directly from the oil pump to the oil pressure screen or filter.
The oil pressure screen or filter element. located on the acccssory housinc is provided u a means to
filter from the
oil
any
solid particles that may have pused thl'Qugb the sumon screen in the sump. After
oelDg filtered In the pressure screen or filter. the oil
is
fed through a drilled passage to the oil pressure
relier'
valve. located in the upper right side of the c:nnkc:asc in front of the accessory housing.
This relief valve regulates the engine oil pressure by aUowin. excessive oil to return to the sump. while
the balance of the pressure oil is fed to the
main
oil pllcry in the right half of the
crankease.
ReSidual oil
15
returned by gravity to the sump where. after pusing through a screen,
it is
aglin circulated through the
englftc.
POWER PLANT
ISSUED: 8/18172
2A12