Vacuum Pump; Connections For Instrumentation; 1) Mechanical Rev Counter And Hourmeter (Optional) - Rotax MMH-912 Series Maintenance Manual

2.3)

Vacuum pump

It is possible to install a vacuum pump for employment of an inertial navigation
system. To do this, the drive kit for the vacuum pump must be retrofitted on
propeller gearbox and crankcase.
◆ NOTE:
Gear ratio:
2.4)

Connections for instrumentation

■ CAUTION:
2.4.1)
Effectivity 912/914 Series
Edition 1 / Rev. 3
BRP-Powertrain
Maintenance Manual
Installation of both the vacuum pump and hydraulic governor is
not possible.
Vacuum pump and hydraulic governor are driven the same way
and therefore have an equivalent gear ratio. See hydraulic
governor.
Consult also the relevant section on connections for instrumen-
tation in the Installation Manual.
Mechanical rev counter and hourmeter (optional)
These are driven from the camshaft via a bevel gear to the rev counter
shaft. A flexible shaft allows connection of a combined instrument, rev
counter or hourmeter. Subsequent installation of a flex. rev counter
shaft is possible after removal of the rev counter cover on the ignition
housing. On engines produced from the year 2007 onwards, it is also
necessary to replace the ignition cover and press the worm gear into
the camshaft using the tool with part no. 877190.
For connection of a rev counter, see 71-00-00 sec. 2.3 item no. 21 (on
912 Series) or item no. 32 (on 914 Series).
The total transmission ratio from crankshaft to rev counter shaft i = 4
◆ NOTE: As the mechanical hourmeter is directly coupled to the
engine speed, the readings may deviate considerably
from those given by electronic hourmeters (e.g. TCU,
FlyDat). Maintenance and overhaul intervals are al-
ways dictated by the flight time.
72-00-00
page 8
October 01/2010