CHAPTER 9
POWER PLANT TROUBLESHOOTING
CHAPTER OBJECTIVES
After completing this chapter, you will be able to:
Recognize the characteristics of a multimeter
Recognize basic troubleshooting procedures
and the use of the high-voltage insulation
and common troubleshooting errors.
tester.
Identify the types and uses of the various
Recognize the purpose of, and the procedures
drawings used in aircraft maintenance publica-
for, the use of the two types of borescopes.
tions.
Recognize the main variables involved when
performing engine tests and the purpose of the
Recognize the codes and methods for the
materials used in engine field cleaning.
identification of various fluid lines.
corrective measure has been taken to correct a
Efficient maintenance of any aircraft depends
malfunction. Never be hasty in assuming any con-
upon the operating and maintenance personnel's
clusions. Do not confuse the significance of cause
familiarity with the aircraft and its associated
and effect. For example, low oil pressure, in itself,
parts. You must have a thorough knowledge of
is not truly a trouble. It is only an indication that
the engine and know its normal operating condi-
a problem exists. the true cause of which is the
tions. You should know the oil pressures, fuel
trouble.
pressure, rpm limits, and exhaust gas temperatures
The preceding paragraph emphasizes the
for all of the engine operating ranges. In addi-
importance of tracing an abnormal indication to
tion to knowing the normal engine conditions, you
its source. Do not be satisfied that restoration to
should understand the effects of atmospheric con-
a normal condition is accomplished by some
ditions on the engine. You must consider such
things as air temperatures and pressure, fuel
obvious adjustment. Adjusting the oil pressure
relief valve setting may not be the only correc-
temperatures, and wind effects.
tion or the correct step for a low oil pressure
discrepancy. Refer to table 9-1 for possible low
oil pressure causes. Invariably, there is a reason
GENERAL ENGINE
for an abnormal engine indication. You must
TROUBLESHOOTING
know the reason and make sure that proper
corrective measures are taken before the
All aircraft maintenance activities are plagued
discrepancy is signed off. Proper corrective
by repeat discrepancies. These discrepancies show
measures require the use of time-proven methods,
up repeatedly on the same aircraft. They show up
not guesswork.
even after being signed off as previously corrected.
As previously stated, to troubleshoot in-
There are many possible causes for repeat
telligently, you must know the system and the
discrepancies. The most common cause is poor
function of each component in the system. You
troubleshooting procedures.
must have a mental picture of the location of each
It is often unsafe to assume that the
component in relation to other components in the
engine is completely repaired when some obvious
9-1
