Ammeter Does Not “Flick” Approximately Every 90 Seconds; Ammeter Flicks Between 90 Second Phase Periods - Piper PA-44-180 SEMINOLE Maintenance Manual

CHART 3004. TROUBLESHOOTING (PROPELLER DEICER SYSTEM) (cont)
Trouble
Ammeter shows normal
current part of cycle,
excess current rest of
cycle. (cont.)
Ammeter does not "flick"
approximately every 90
seconds.
Ammeter flicks between
90 second phase periods.
PIPER AIRCRAFT
PA - 4 4 - 1 8 0 / 1 8 0 T
AIRPLANE MAINTENANCE MANUAL
Cause
Ground between brush
block and deicers.
Short between two adjacent
circuits.
Timer faulty.
Timer ground open, timer
not cycling.
Timer contacts are
welded (caused by short
circuit in system).
Loose connection between
aircraft power
supply and timer input.
2E6
Remedy
If no short exists at brush
slip ring contact, check for
ground from slip ring lead
to propeller assembly while
flexing slip ring and
deicer leads. If a
ground is indicated,
locate and correct.
Check for cuts or low
resistance between circuits.
If any, locate
and correct.
Test timer.
Disconnect harness at
timer and check with
ohmmeter from Pin A
(of harness) to ground.
If no circuit, fix open
per schematic diagram.
Test timer. If timer
does not cycle with voltage
at Pin B, replace.timer but
be sure short causing
original failure has been
located and corrected.
Trace wiring from power
source to timer input to
insure that the electrical
contacts at each connection
in the circuit are good.
Revised: May 15, 1989
3 0 - 6 2 - 0 0
Page 30-26