Timer 1 and 2 are the same timer, the #2 is a standby.
When selected to either timer the brush blocks transfer electrical current to the slip rings which are connected to the propeller blades.
Power is supplied to opposite blades to ensure propeller balance.
- Propeller heating sequence:
- Left propeller blades 1 and 3, Right propeller blades 1 and 3.
- Left propeller blades 2 and 4, Right propeller blades 2 and 4.
Over heat damage protection on the ground is provide by the 40psid engine oil low pressure switch.