Piper PA-28-161, Maintenance Manual

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PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 1
Nov 30/06 5F13
80-10-00
CRANKING
1. Description (See Figure 1.)
When the starting circuit is energized, battery current is applied to the starting motor terminal. Current
flows through the field coils creating a strong magnetic field. At the same time, current also flows through
the brushes and commutator, and finally through the armature to ground. The result is a high cranking
torque, for a limited period of time, with a high current flow at a minimum loss of voltage.
The drive end gear of the armature mates with the reduction gear which drives the Bendix shaft. The
Bendix drive is held in position on the shaft by a spirol pin. As the armature turns the reduction gear, the
Bendix drive pinon meshes with the starter drive gear by inertia and action of the spirol grooves within
the Bendix unit. A detent pin engages in a notch in the screw threads which prevents demeshing if the
engine fails to start. When the engine does start and reaches a predetermined speed, centrifugal action
forces the detent pin to release and allows the pinion to demesh from the starter drive gear.
2. Troubleshooting
See Chart 1.
NOTE: In Chart 1, for any remedy which requires disassembly and cleaning or repair of the starter;
replacement with a new, or known good, unit is always an alternative solution.
NOTE: NEVER USE JUMPER CABLES to test voltage to the starter. The "toothed" jaws of jumper
cables are meant to "bite" into soft, leaded terminals on car batteries, and simply WILL NOT
provide enough contact with the starter terminal to supply the needed amperage to engage the
starter properly.
NOTE: Use an analog voltage meter if you can. Digital meters take intermittent 'snap shots' of voltage.
In situations where voltage is being supplied intermittently (even in rapid cycles), the digital
meter will simply not provide the correct 'picture' of the aircraft's voltage situation.
3. Starter
WARNING: FAILURE TO CONSULT APPLICABLE VENDOR PUBLICATION(S), WHEN SERVICING
OR INSPECTING VENDOR EQUIPMENT INSTALLED IN PIPER AIRCRAFT, MAY
RENDER THE AIRCRAFT UNAIRWORTHY. (SEE INTRODUCTION - SUPPLEMENTARY
PUBLICATIONS.)
A. Removal
CAUTION: TO PREVENT SHORT CIRCUITING, DISCONNECT THE GROUND CABLE FROM
THE BATTERY BEFORE REMOVING THE STARTER FROM THE ENGINE.
(1) Disconnect starter cable from starter terminal post.
(2) Remove mounting bolts.
(3) Lift off starter motor.
B. Installation
(1) Clean all traces of rust, corrosion, or dirt from all mounting surfaces and mounting hardware.
All ground points or straps must be clean and tight.
(2) Place starting motor in position with no stresses or binding forces being present and install
mounting bolts. Torque bolts to 204 in.-lbs. or as specified in Lycoming SSP-1776.
(3) Reinstall starter cable to starter terminal post. Torque to 24 in.-lbs. or as specified in Lycoming
SSP-1776.
(4) Reconnect ground cable to negative post of battery.
(5) Perform cranking tests, below.