MD Helicopters CSP-900RMM-2 Servicing And Maintenance Download

Page: 1457 / 2144

CSP

−

900RMM

−

MD Helicopters, Inc.

Rotorcraft Maintenance Manual

Page 5

Revision 19

63-00-00

3. Lubrication Subsystem

(Ref. Figure 2)

The transmission is cooled by ambient air
passing over the external housings and by
pressurized oil lubrication of the internal
components. The oil is cooled by using two (2)
transmission driven fans to draw outside air
through two (2) air/oil heat exchangers
through which the oil is circulated and cooled.

Oil operating temperature is maintained below
230

F (159.7

C).

The lubricating subsystem consists of the
following components:

Lubrication Pump -

pressurizes and

circulates oil from the main transmission
sump through the gear train.

Filter Unit -

bypass filter eliminates particles

from the lubricating oil.

Oil Level Indicator -

a visual sight gage

mounted on the main transmission.

Pressure Transducer -

sends an oil pressure

signal to the IIDS display.

Pressure Switch -

illuminates the main

transmission low oil pressure light on the IIDS
display.

Temperature Probe/Switch -

measures oil

temperature and illuminates the oil overheat
light on the IIDS display.

Magnetic Chip Detector -

detects metal

particles in the main transmission oil.

Vent/Breather -

eliminates gear case heat

and oil vapors from the lubrication system.

Cooling Blowers -

provide cooling air to the

oil coolers.

Oil Coolers -

provide a heat exchange with

ambient air to cool the transmission lubricat
ing oil.

Blower Ducts -

provide inlet and exhaust

passages for ambient air to enter and exit the
cooling blowers.

A. Lubrication Pump

An unregulated pressure positive displacement
gerotor pump used to circulate the oil through
the filter, oil coolers and transmission oil
passages and jets.

B. Filter Unit

A dual stage replaceable filter contained
within a cast aluminum alloy located inside
the lubrication pump is used to eliminate
particles contained in the lubricant. The
replaceable first stage filter is a 75 micron
nominal element and the replaceable second
stage is a 3 micron nominal element. The unit
contains a bypass system to allow continued
unfiltered pressurized lubrication in the event
the filters become clogged. The bypass system
is designed to prevent debris already trapped
in the filter elements from being reintroduced
into the transmission.

C. Oil Level Indicator

A clear prismatic window is located on the
lower right side portion of the main case
housing. It is used to visually indicate the
static level of lubricant contained within the
sump area of the transmission. The window is
surrounded by a frame which is marked with
the proper lubrication service level.

D. Pressure Transducer

A pressure transducer mounted on the main
transmission measures main transmission oil
pressure. The transducer sends a signal to the
main transmission oil indicator on the IIDS
display. The IIDS monitors the oil pressure. If
oil pressure drops below 35 psig at 100% Rotor
rpm (N

) a caution light illuminates. If oil

pressure drops below 30 psig at 100% N

16 psig at 65% N

(idle), a warning light

illuminates on the IIDS display.

E. Pressure Switch

A pressure switch mounted on the main
transmission completes an electrical circuit to
illuminate the main transmission low oil
pressure light on the IIDS display. The switch
completes an electrical circuit when oil
pressure decreases below 20 psig at 100% N

MD Helicopters CSP-900RMM-2, Servicing And Maintenance

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