Systems Guide

Aerosoft
Twin Otter E
XTENDED
Systems
Vol
2
2-1-11
19 November 2013
400 Cycle
Not simulated
FWD Fuel Level
Indicates < 75 pound of fuel in forward
tank
Check fuel gauges
AFT Fuel Level
Indicates < 110 pound of fuel in aft tank
Check fuel gauges
Boost Pump 1
AFT Press
Indicates fuel boost pressure below 2 PSI
and pump is switched off
Automatic changeover will
activate the secondary pump.
When boost pumps on one tank
fail, feed both engines from the
other tank
Boost Pump 2
AFT Press
Boost Pump 1
FWD Press
Boost Pump 2
FWD Press
HYDRAULIC SYSTEM
Hydraulic pressure in the Twin Otter is provided by an electrical constant volume pump running from the left
electrical bus and the whole system is fully automated. There are no controls of any kind in the cockpit. Nose
wheel steering, flaps and wheel brakes are operated hydraulically.
HYDRAULIC PRESSURE INDICATION
There are two gauges that show hydraulic pressure, the system pressure indicator and the brake pressure
indicator. Both will show identical pressure, only when there is a system pressure failure the brake pressure
indicator will show the remaining pressure retained for braking.
PNEUMATIC / BLEED SYSTEM
The pneumatic system is only used to provide hot air to the heating and de-icing system and the auto pilot.
When pressure drops below 20 psi the bleed air will only be usable for anti-icing operations and not for cabin
heating. This is indicated by LOW PRESSURE caution lights.
BLEED AIR SWITCHES
Two bleed air switches on the overhead console can be toggled between BLEEDAIR and OFF to activate /de
activate the bleed air shutoff valve in the selected engine.
HEATING
Hot bleed air is mixed with cold outside air from a ram air scoop to maintain comfortable cabin temperature. A
electrical fan is installed with the ram air scoop to provide air flow when stationary and is controlled by a VENT
FAN switch. When the heating ducts are overheating a DUCT OVERHEAT caution light will illuminate.
OPERATING
In all normal operation the system will run in automatic mode.
FIRE DETECTING AND EXTINGUISHING SYSTEMS
Both engine nacelles contain fire detection and extinguishing systems. Temperature sensors will monitor
temperature and when an overheat condition is detected the fire bell will sound and the fire extinguisher