IO-390-D Series Engine Maintenance Manual
05-50
© 2020 Avco Corporation. All Rights Reserved
Page 48
March 2020
IO-390-D Series Engine Maintenance Manual
NOTICE:
Refer to the engine specifications in Appendix A of the
IO-390-D Series Engine
Installation and Operation Manual
for rated engine speed.
All incidents of engine overspeed must be recorded in the engine logbook along
with any corrective action identified herein.
(2)
If an engine is operated at overspeed for more than 3 seconds, identify the category of
percent of overspeed based on the three categories of overspeed shown in Table 1. Refer
to the latest revision of Service Bulletin No. SB-369 for additional details.
Table 1
Overspeed Values for IO-390-D Series Engines
Overspeed Category
rpm
Corrective Action
Engine overspeed less
than 5% in excess of
maximum rated rpm for
more than 3 seconds
2701
to
2834
a.
Identify and correct the cause of the overspeed.
b.
In the engine logbook, record the overspeed incident and any
inspections and corrective action.
Engine overspeed
between 5% and 10%
in excess of maximum
rated engine rpm for
more than 3 seconds.
2835
to
2970
a.
Identify and correct the cause of the overspeed.
b.
Complete the “Cylinder Overspeed Inspection” procedure in this
chapter.
c.
Refer to Chapter 12-10:
(1)
Drain the lubricating system.
(2)
Remove the suction screen and oil filter.
(3)
Examine the suction screen and oil filter element for metal
contamination. If any unexplained metal accumulation is found,
identify and correct the cause before putting the engine back into
service.
d.
Complete the “Valve Train Overspeed Inspection” procedure in this
chapter.
e.
Complete the “EIS Overspeed Inspection” or “Magneto Overspeed
Inspection" in this chapter.
f.
In the engine logbook, record the overspeed incident and any
inspection and corrective action.
Engine overspeed more
than 10% in excess of
maximum rated engine
rpm for any duration
2971 or
more
for any
length
of time
a.
Remove the engine from the aircraft. Refer to the “Engine Removal”
procedure in Chapter 72-00.
b.
It is recommended the engine be sent to Lycoming Engines for
customized evaluation. Include a description of the overspeed
incident, amount of overspeed, and duration.
c.
In the engine logbook, record the overspeed incident and any
inspections and corrective action.
OR
Refer to Chapter 72-05 and the latest revision of Service Bulletin No.
SB-240
to:
•
Disassemble the engine
•
Complete an inspection of the engine
•
Replace any parts that are damaged or not in compliance
•
Replace any parts that must be replaced at overhaul or upon removal
