PIPER SENECA II SERVICE MANUAL
01/01/09 XIV - ACCESSORIES AND UTILITIES
3A9
SECTION XIV
ACCESSORIES AND UTILITIES
14-1. INTRODUCTION.
This section covers accessories which are available for this airplane and not covered in other sections of
this Service Manual. This information provides instructions for remedying difficulties which may arise
in any of the accessories, and the instructions are organized so the mechanic may refer to whichever
component or system he must service.
14-2. TROUBLESHOOTING.
A troubleshooting chart is located at the end of each accessory covered in this section. The various
troubles and suggested remedies found in the tables are provided to assist in locating and correcting
malfunctions in the particular system.
14-3. PROPELLER DEICING SYSTEM.
NO
TE: For Two (2) blade (aluminum) propeller installations, see latest revision of Hartzell Propeller
Electrical De-ice Boot Removal and Installation Manual, Manual No. 182 (61-12-82).
14-4. DESCRIPTION AND PRINCIPLES OF OPERATION. (Refer to Figure 14-1.)
The Propeller Deicing System consists of an electrically heated deicer (1) bonded to each propeller
blade, a slip ring assembly (2) with a brush block assembly (3) to transfer electrical power to the rotating
deicers, a timer (4), an ammeter (5), a control switch circuit breaker (7), shunt (6), together with wiring
harnesses (8) to complete the circuit. Power is drawn from the aircraft electrical system (10).
Dual element deicers are utilized on the two blade propeller installation. Each deicer has two separate
heaters; one for the outer half and one for the inner half. By heating all outer or inner heaters on only
one propeller at a time, rotational balance is held during deicing. Current is drawn from the airplane
electrical system through the switch, ammeter and timer. The timer successively delivers current via the
slip ring and brush block arrangement to (phase 1) the outer heaters on the right propeller, (phase 2) the
inner heaters on the same propeller, (phase 3) the outer heaters of the left propeller and (phase 4) the
inner heaters on the left propeller. The timer energizes each of these four phases in turn for about 34
seconds and then repeats the cycle as long as the control switch is on. The cycling sequence given is vital
so that outboard heaters on each propeller operate before the inboard heaters. See cycle sequence. (Refer
to Figures 14-2 thru 14-5.) The system may be used continuously in flight if needed. To conserve
electrical power, current is cycled to the deicer heaters at timed intervals rather than continuously.
NO
TE: Heating may begin at any phase in the cycle depending on the timer position when the switch
was turned off from previous use.
The optional McCauley three bladed propeller installation utilizes single element deicers. When the
switch is turned on power is directed through the brush block and slip ring to all the heating elements on
one propeller for approximately 34 seconds. The timer then directs the power to the other propeller for
approximately 34 seconds. This cycle continues until the switch is turned off.
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