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IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
Problem
Engine will not turn
static rpm or will not
develop rated rpm
(Cont.)
© 2020 Avco Corporation. All Rights Reserved
March 2020
Table 1 (Cont.)
Fault Isolation Guide
Cause
Too much air dropped
through a new air filter
Defective air filter
Propeller is out of
adjustment (not reaching
low pitch)
Fouled spark plugs
Incorrect fuel flow
Incorrect type of fuel
Throttle lever is
incorrectly adjusted
Insufficient combustion
Corrective Action
1. Put the aircraft in a dust-free area.
2. Remove the air filter.
3. Operate the engine to full throttle.
4. If the engine operates at full rpm,
replace the air filter with a new air
filter.
Adjust the propeller in accordance with
airframe or propeller manufacturer's
instructions.
• Spark Plug Removal
• Spark Plug Cleaning
• Spark Plug Fouling
• Spark Plug Gap Setting
• Spark Plug Rotation
• Spark Plug Installation
1. Look for blocked fuel lines to the
engine.
2. Remove the fuel injector inlet screen
and flush out with acetone or MEK.
Blow out with compressed air.
3. Disconnect the fuel flow gage and
install a master fuel flow gage to
make sure the aircraft fuel flow gage
is accurate.
4. Replace the fuel injector* as
necessary. Refer to the "Fuel Injector
Replacement" procedure.
Refer to the section "Incorrect Fuel or
Fuel Contamination."
Adjust the throttle lever in accordance
with airframe manufacturer's
instructions.
1. Complete a "Cylinder Compression
Check Procedure."
2. Complete a "Borescope Inspection
Procedure" to look for excessive
wear on the cylinders or damaged
valve and valve seats.
Ref.
AMM
AMM
74-20
&
05-30
73-10
05-50
72-30
12-30
Page 89
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