FIELD LEVEL TROUBLESHOOTING INTRODUCTION
This chapter contains step-by-step procedures for identifying, locating, isolating, and repairing the PLS AC system
This technical bulletin cannot list all malfunctions that may occur, nor all test or inspections and corrective actions.
If a malfunction is not listed or is not corrected by listed corrective actions, notify Supervisor.
Troubleshooting procedures are divided into logic tree pages and test pages.
a. Page Layout.
1. A logic tree page is always a left-hand page, facing the test page on the right. The logic tree page
provides the sequence of steps required to isolate a fault to a failed component. All critical information
for decision making is on the left-hand page. Each logic tree page contains the following information:
(a) INITIAL SETUP This box is located only on the first logic tree page of a fault. INITIAL SETUP lists
tools, materials, references, personnel, and equipment needed to troubleshoot the fault.
(b) KNOWN INFO This box is located in the top left-hand column. KNOWN INFO lists conditions and
information that will eliminate specific components as the cause of the fault.
(c) POSSIBLE PROBLEMS This box is located directly below KNOWN INFO. All of the system
components that could cause a fault are listed in the POSSIBLE PROBLEMS box. The first
component listed in the POSSIBLE PROBLEMS box is the one that will be tested at that step in the
logic sequence. When one of the components is tested and found to be operational, it is entered at
the bottom of the KNOWN INFO box as OK.
(d) QUESTION Each question, located in the middle column, refers to the first possible problem listed
in POSSIBLE PROBLEMS. If the answer to the question is YES, proceed to the next step. If the
answer is NO, follow the NO arrow to obtain directions for correcting the problem. If the step
contains a WARNING or CAUTION message, a small shadow box is printed above the question.
Text for WARNINGS and CAUTIONS is on the following right-hand page.
(e) TEST OPTIONS This box is located in the top right-hand column. TEST OPTIONS lists tests
available for testing parts suspected of failing.
(f) REASON FOR QUESTION This box is located directly below TEST OPTIONS. It explains the
purpose for the question in the middle column.
2. A test page is always a right-hand page, facing the logic tree page on the left. The test provides detailed
instructions for testing the first component listed in the POSSIBLE PROBLEMS box. This test will also
provide an answer for the question in the middle column. Note the arrow connecting the test on the
right-hand page to the REASON FOR QUESTION. When possible, illustrations are included to provide
visual details. Warnings, cautions, and notes contain additional information for testing.
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