IO-390-D Series Engine Maintenance Manual
05-20
© 2020 Avco Corporation. All Rights Reserved
Page 12
March 2020
IO-390-D Series Engine Maintenance Manual
Visual Inspection Checklist for IO-390-D Series Engines (Cont.)
Cylinders - Refer to figures in Chapter 72-30.
Item to Examine
Cyl. 1
Cyl. 2
Cyl. 3
Cyl. 4
NOTICE:
During the first hours of service, engines can have some leakage at the cylinder base or
the cylinder base studs. This initial leakage is not harmful or detrimental to the engine.
Oil leakage - Identify and correct the
cause.
Exhaust or combustion residue - Identify
and correct the cause.
Examine the cylinders for heat damage
i.e. burnt paint and damaged fins.
(Identify whether the paint has scaled or
peeled from discolored and blistered
paint appearance. Unburned metallic
surfaces appear bright or clean with
definite edges.) - Identify and correct the
cause.
Examine the exhaust system, exhaust
flange and port connections for leaks in
connections between the exhaust system
and exhaust ports of cylinders - look for
burnt paint around the spark plug and
exhaust flange bosses or for light gray
deposits near the leaks; look for a warped
exhaust flange (which can cause a leak.) -
Identify and correct the cause. Replace
exhausts that have a warped flange.
Examine studs on the cylinder head for
looseness or damage. Replace loose or
damaged studs.
Examine the following for cracks, rust/pitting and damage - replace cracked, rusted, pitted or
damaged cylinders.
External cylinder barrel and cooling
fins.
External surface of the cylinder head
and fins including areas between and
adjacent to the fins.
Look for any radial fin crack
extending to the root of a fin on the
cylinder.
Top and bottom spark plug bosses.
Follow-Up Action:
