IO-390-D Series Engine Maintenance Manual
12-30
© 2020 Avco Corporation. All Rights Reserved
Page 88
March 2020
IO-390-D Series Engine Maintenance Manual
Table 1 (Cont.)
Fault Isolation Guide
Problem
Cause
Corrective Action
Ref.
Low fuel flow
(Cont.)
Fuel line to fuel flow
gage is broken, loose, or
blocked
Look for fuel dye stains to identify
leaky, cracked, damaged or loose fuel
lines. Replace any cracked or damaged
fuel line. Refer to the “Fuel Line
Replacement” procedure.
To identify a blocked fuel line,
disconnect the line at both ends and
blow it out with compressed air. Re-
connect the fuel line. Torque as per the
latest revision of the
Service Table of
Limits SSP-1776
. Make sure the fuel
line is no longer blocked.
73-10
Low fuel pressure
1.
Examine the fuel filter for plugs;
replace a plugged fuel filter as per
the aircraft manufacturer’s
instructions.
2.
Adjust the fuel pressure in
accordance with the aircraft
manufacturer’s instructions.
3.
Replace the fuel pump* or fuel
pressure regulator. Refer to the “Fuel
Pump Replacement” procedure.
AMM
73-10
Engine will not turn
static rpm or will not
develop rated rpm
Decreased air flow in the
induction system
1.
Make sure that the air filters are clean.
2.
Complete the “Induction System
Inspection” and remove all blockages.
3.
Make sure that the air box is installed
in accordance with the airframe
manufacturer's specifications.
4.
Repair or replace the air inlet or
manifold if necessary.
72-80
AMM
Blockage in air inlet or
manifold
Air filter dirty
Replace the air filter.
NOTICE:
Occasionally new air filters
will have an excessive air drop through
them. If this condition is suspected,
remove the air filter and operate the
engine to full power on a hard surface
in a dust-free area.
AMM
* Review any applicable warranty information relative to replacement of a fuel component as per the
latest revision of Service Letters L221 and L253.
