Propeller Tachometer-Generator; Starter-Generator - Textron Cessna Grand Caravan Ex 208B Pilot's Operating Handbook And Faa Approved Airplane Flight Manual

CESSNA SECTION 7
MODEL 208B 867 SHP AIRPLANE AND SYSTEMS DESCRIPTION
GARMIN G1000

PROPELLER TACHOMETER-GENERATOR

The propeller tachometer-generator produces an electric signal which
is used in conjunction with the propeller RPM indicator. The propeller
tachometer- generator drive and mount pad is located on the right side
of the reduction gearbox case and rotates clockwise with a drive ratio of
0.1273:1.
TORQUEMETER
The torquemeter is a hydro-mechanical torque measuring device
located inside the first stage reduction gear housing to provide an
accurate indication of engine power output. The difference between the
torquemeter pressure and the reduction gearbox internal pressure
accurately indicates the torque being produced. The two pressures are
internally routed to bosses located on the top of the reduction gearbox
front case and to a pressure transducer which is electrically connected
to the G1000 which indicates the correct torque. For standby indication,
the pressures are routed to bosses on the top of the reduction
gearcase front case and plumbed to the standby torque indicator.

STARTER-GENERATOR

The starter-generator is mounted on the top of the accessory case at
the rear of the engine. The starter-generator is a 28-volt, 200-amp
engine-driven unit that functions as a motor for engine starting and,
after engine start, as a generator for the airplane electrical system.
When operating as a starter, a speed sensing switch in the
starter-generator will automatically shut down the starter, thereby
providing overspeed protection and automatic shutoff. The
starter-generator is air cooled by an integral fan, ram air ducted from
the front of the engine cowling and on airplanes equipped with the 300
amp starter generator, ram air is also supplied from a NACA scoop
located on the nosewheel fairing.
208BPHCUS-00 7-69
U.S.