IO-390-D Series Engine Maintenance Manual
05-20
© 2020 Avco Corporation. All Rights Reserved
Page 28
March 2020
IO-390-D Series Engine Maintenance Manual
7.
400-Hour Engine Inspection for IO-390-D Series Engines
The purpose of this inspection is to examine the engine cylinders and to complete a cylinder
borescope inspection on each cylinder.
A.
Complete the 400-Hour Engine Inspection after every 400 hours of operation since the
engine has been in service.
B.
Copy and complete the 400-Hour Engine Inspection Checklist for IO-390-D Series Engines
as a record of engine service. Record the engine hours.
WARNING
BEFORE ANY ENGINE INSPECTION OR SERVICE PROCEDURE,
MAKE SURE THE IGNITION SWITCH IS SET TO OFF AND THAT ALL
POWER TO THE ENGINE IS DISCONNECTED. ENSURE ALL
OBJECTS/PERSONNEL ARE CLEAR OF THE PROPELLER’S
ROTATIONAL ARC. IF POWER IS ON, A LOOSE OR BROKEN WIRE
CAN CAUSE THE ENGINE TO START AND THE PROPELLER TO
TURN WHICH CAN LEAD TO DEATH OR SERIOUS INJURY OR A
PROPELLER STRIKE.
400-Hour Engine Inspection Checklist for IO-390-D Series Engines
Engine Model Number___________________
Engine Serial Number:___________________
Engine Time:___________________________
Date Inspection Done:____________________
Inspection done by:______________________________
Inspection Item
Comments
Results/Notes
Done
Complete the 100-Hour or
Annual Engine Inspection
Checklist.
Refer to the section “100-
Hour or Annual Engine
Inspection for IO-390-D
Series Engines” in this
chapter.
Cylinders
Remove the rocker box covers
from all of the engine cylinders.
Look for evidence of wear or
broken parts in the area of the
valve tips, valve keeper, springs,
and spring seats. If any of these
conditions are found, remove the
cylinder and piston and examine
for further damage.
Refer to the “Cylinder
Removal” procedure in
Chapter 72-30.
