Propeller Deice System Description And Operation; Propeller Deice System Troubleshooting - Piper PA-44-180 SEMINOLE Maintenance Manual

PROPELLER DEICE SYSTEM.
DESCRIPTION AND OPERATION.
The B.F. Goodrich propeller deice system installed on the PA-44-180T uses the single element type deicer
boots. In this type system each deicer has one electrothermal heating element. When the PROP HEAT switch on
the instrument panel is turned ON, the timer directs power through the modular brush assembly and slip ring to
all the heating elements on one propeller for approximately 90 seconds. The timer then switches power to all the
heating elements of the other propeller for approximately 90 seconds. This cyclewill continue as long as the
PROP HEAT switch is in the ON position.
The propeller deice system consists of the following: electrically heated boots bonded to each propeller blade:
slip ring assemblies connected to the propeller hubs to distribute power to the propeller deicers; modular brush
assemblies which transfer electrical power to the rotating slip rings; a timer to cycle power to the deicers in the
proper sequence; an ammeter to indicate that the system is functioning correctly; an external ammeter shunt; a
manual ON/OFF, rocker-type switch and a circuit breaker.
TROUBLESHOOTING.
Troubles peculiar to the propeller deicing system are listed in Chart 3004 along with their probable causes and
suggested remedies.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
2E2
3 0 - 6 2 - 0 0
Page 30-22
Revised: May 15, 1989