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PA-46-350P, MALIBU
7.5
ENGINE AND PROPELLER (continued)
from overboost damage by limiting manifold pressure to 42.0 in. Hg. In the
event of a controller malfunction, there is a pressure relief valve on the
induction manifold which will relieve manifold pressure and prevent an
overboost.
When descending from altitude, care should be exercised to maintain
engine power and temperatures (oil, CHT). Turbocharger compressors
supply air for cabin pressurization and power reduction below that
recommended could cause a decrease in cabin pressure. Sudden cooling or
gradual extreme cooling of engine cylinders will accelerate engine wear.
Follow normal descent procedures described in Section 4.
The engine is equipped with a Bendix RSA-10ED1 fuel injection system.
An engine-driven fuel pump supplies fuel under pressure to the fuel injection
regulator, which measures air flow and meters the correct proportion of fuel
to a flow divider. The flow divider then directs the fuel to each of the
individual cylinder injector nozzles. A fuel vent system provides a common
reference vent pressure to the fuel pressure switch, engine-driven fuel pump
and injection nozzles. The vent source is taken downstream of the
turbochargers to ensure proper vent pressure during turbocharger
operation.
The engine employs a full pressure, 12 quart wet sump lubrication
system (Figure 7-3). Maximum endurance flights should begin with 12
quarts of oil. The sump is filled through a combination dipstick oil filler cap.
Lubricating oil is drawn through the oil sump inlet screen by the engine oil
pump and directly to the oil cooler and a thermostatic bypass valve. When
engine oil is cold, the thermostatic bypass valve will open allowing oil to flow
directly to the full flow oil filter bypassing the cooler. As the oil warms up,
the bypass valve will close thereby forcing more oil to circulate through the
cooler prior to entering the oil filter. From the oil filter, the oil passes
through an oil pressure relief valve which regulates system oil pressure. The
regulated oil is then routed to the waste gate actuator, turbochargers, and
through the main oil galleries to the various engine bearings, piston oil
cooling nozzles, valve mechanisms, and moving parts. Gravity returns the oil
to the sump.
The turbochargers are also lubricated by the regulated oil from the
engine system. Oil circulated through the turbochargers is returned to the
sump by a scavenge pump attached to the hydraulic pump accessory pad. Oil
from the oil pump is also supplied directly to the waste gate control system.
ISSUED: FEBRUARY 23, 1999
SECTION 7
DESCR/OPERATION
REPORT: VB-1710
7-5
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