Power Plant Pa-24-250 And - Piper PA-24 Comanche Service Manual

PIPER COMAl\4CHE SERVICE MANl'AL
SECTIO:" VilA
POWER PLA:"T PA-24-150 A:"D PA-24-260
•
7A- L Introduction. This section covers power plants used in the
PA~24~250
and PA-24-2flO and i...
comprised of instructions for the removal, minor repair. service and installation of the engine cowlinc.
propeller. propeller
governor.
engine. engine shock mounts. induction system. ignition ... ~ . . .
tern
an~d
lubrication system.
iA-2, Description. The PA-24-250 and
PA-14~260
Comanche is powered bv an Avco-Lvcominz enuine of
either 250 or 260 horsepower. (Refer to Power Plant Specifications in Table II-\.) Engines are ().5~1i serie...
or 10-540 serie. . . which are six cylinder direct drive. wet sump. horizontally opposed, air-cooled. and are
designed to operate on 91 90 (minimum) octane aviation grade fue\.
CO\\ ling completely encloses the engine and consists of an upper and lower section. Side pa nct- lift up
to allow access to the engine.
The propeller may be a constant speed McCauley or Hartzell unit controlled by a gov ernor mounted on
the engine supplying oil through the propeller shaft at various pressures. Oil pressure from the
governor
moves the blades into high pitch (reduced RPM) and centrifugal twisting moment of the blades tend
to
move them into 10\\ pitch (high RPM) in the absence of governor oil pressure.
The induction system consists of a wet type air filter on the early models or a
dr~
type air filter on the
later models and a M A-4-5 Marvel-Schebler carburetor or a Bendix fuel injection unit. The engines are
normally aspirated with no restrictions on maximum power output.
Bendix Scintilla S6l:"-20 series and S6L:"-200 series magnetos are installed with their associated
components. The Sel,
~-20
series magnetos incorporate a single breaker and an impulse coupling i n s t .
on the left magneto. The
Sf'll~-200
series magneto system consists of a single contact magneto on the
side of the engine and a dual contact magneto on the left. to obtain the retard spark necessary for starting.
A starting \ ibrator. magneto switches and starter switch complete the system.
In addition to the previously mentioned components. each engine is furnished with a 12-\olt starter. a
I
~-\
olt.
~5-ampere
or 50-ampere generator or a 70-ampere alternator: a vacuum pump drive and fuel pump.
The lubrication system is of the pressure wet sump type. The oil pump. which is located in the
accessory housing. draws oil through a drilled passage leading from the oil suction screen located in the
sump. The oil from the pump then enters a drilled passage in the accessory housing. which feeds the oil to a
threaded connection on the rear face of the accessory housing. where a flexible line leads the oil to the
external oil cooler. Pressure oil from the cooler returns to a second threaded connection on the accessory
housing from which point a drilled passage conducts oil 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 prov ided 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 accessory housing is provided as a means to
filter from the oil any solid particles that may have passed through the suction screen in the sump. After
being filtered in the pressure screen or filter. the oil is fed through a drilled passage to the oil pressure relief
valve. located in the upper right side of the crankcase in front of the accessory housing.
ISSrED: 8/18/72
2C4
POWER
Pl..