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IO-390-D Series Engine Maintenance Manual
IO-390-D Series Engine Maintenance Manual
05-50 - UNSCHEDULED CORRECTIVE MAINTENANCE
1. Unscheduled corrective maintenance is necessary when any of the following conditions occur:
A. Lightning Strike
B. Engine Overspeed
C. Incorrect Fuel or
Fuel Contamination
D. Soaked Engine
NOTICE: Except as noted in this chapter, the term "magneto" can refer to either the Lycoming
Electronic Ignition System (EIS) or optional, traditional magnetos, depending on the
type of system installed on the engine.
A. Lightning Strike - After a lightning strike:
After a lightning strike, if there is external evidence of electrical damage to the engine or
propeller or evidence of magnetism of the engine or propeller, before the next flight, complete a
visual inspection of the engine and propeller for electrical arc damage (in accordance with the
airframe and propeller manufacturer's recommended procedures/guidance).
If there is evidence of arc damage, send the engine either to Lycoming Engines or an FAA
authorized repair facility for an internal inspection and evaluation on whether an engine repair or
overhaul is necessary.
OR
Complete the following in the field in accordance with this manual:
(1) Remove, disassemble, and clean the engine (per Chapters 72-00, 72-05, and 05-30).
(2) Complete an inspection of the engine and its components per chapters in this manual and
the latest revision of Service Bulletin No. SB-401.
NOTICE: If the EIS does not function correctly or has visible indications of damage,
replace the EIS.
(3) Examine the engine compartment in the aircraft, the engine, external surfaces, internal
parts for discoloration, cracks, and other indications of arcing and heat damage.
NOTICE: Refer to the latest revision of Service Bulletin No. 240 which identifies certain
parts that must be replaced on engine reassembly. Do not re-install any part if it
is discolored, cracked, or damaged. Replace the part with a serviceable part.
(4) Assemble the engine (per Chapter 72-10) and complete an Operational Ground Check
(per Chapter 72-00).
(5) Record the incidence of a lightning strike, inspection outcome, and any corrective action
in the engine logbook.
B. Engine Overspeed
CAUTION
(1) In engine overspeed, the engine operates above its rated (speed) revolutions per minute
(rpm). Momentary overspeed is an increase of no more than 10% of rated engine rpm for
a period not exceeding 3 seconds. If the duration and amount of overspeed is calculated to
fall within the limitations defined as momentary, no further maintenance actions are
necessary.
© 2020 Avco Corporation. All Rights Reserved
March 2020
E. Engine on Fire or
Near Fire
F. Hydraulic Lock
G. Volcanic Ash/
Particulate
Contamination
DO NOT OPERATE THE ENGINE CONTINUOUSLY AT AN
OVERSPEED RATE BECAUSE PARTS CAN WEAR OUT AND
EVENTUALLY CAUSE ENGINE FAILURE.
H. Valve Sticking
I. Oil Starvation/Sudden Loss of Oil Pressure
J. Metal Contamination of the Lubrication
System
K. Propeller Strike, Sudden Engine Stoppage,
or Loss of Propeller Blade Tip
05-50
Page 47
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