IO-390-D Series Engine Maintenance Manual
© 2020 Avco Corporation. All Rights Reserved
12-30
March 2020
Page 83
IO-390-D Series Engine Maintenance Manual
12-30 - FAULT ISOLATION
1.
Recommended Approach to Fault Isolation
A.
Refer to the Fault Isolation Guide in Table 1.
B.
Visually examine the engine for indications of obvious problems, such as intake and exhaust
valve leaks, physical damage to ignition wires and ignition harness, blocked breathers, fuel
and oil stains, etc.
C.
Review maintenance logs to identify any trends or possible causes.
D.
Discuss any operational problems with the pilot to identify background, details or incidents
of unusual operation.
E.
Record all findings and corrective action.
2.
Fault Isolation Guide
A.
The Fault Isolation Guide in Table 1 shows the more common and recurring problems,
causes, and corrective actions. Continue from the simplest to the most complex possible
causes.
B.
The "Ref." column in Table 1 contains references to the following:
(1)
A numeric entry such as "72-00" refers to a chapter in this manual.
(2)
IOM refers to the
IO-390-D Series Engine Installation and Operation Manual
.
(3)
AMM refers to the
Airframe Manufacturer’s Manual.
(4)
POH refer to the
Pilot’s Operating Handbook.
Table 1
Fault Isolation Guide
Problem
Cause
Corrective Action
Ref.
Engine will not start
or starts with
difficulty
Incorrect starting
procedure
Obey starting procedures or the Pilot’s
Operating Handbook.
IOM
POH
Throttle valve open too
far
Set the throttle control approximately
1/4 (of the length of throttle control
travel) open for about 800 rpm.
AMM
Discharged battery
Replace with a charged battery.
AMM
Faulty starter
Complete the “Starter Replacement”
procedure.
72-70
No fuel or low fuel level
Complete a check of the fuel supply.
Service as required.
AMM
No fuel flow
Blockage in fuel line
1.
Disconnect the fuel line.
2.
Complete a check of the fuel flow.
3.
Examine for evidence of leaks and
correct as required.
4.
Clean the filters, strainers, lines, or
fuel valves.
73-10
