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Volcanic Ash
• Given the dynamic conditions of volcanic ash, Lycoming's recommendation is NOT to operate
the engine in areas where volcanic ash is present - in the air or on the ground. Refer to the latest
revision of Service Instruction No. SI-1530 for any new details.
• Ash on the ground and runways can cause contamination in the engine compartment and
subsequent engine damage during aircraft landing or take-off.
• Piston engines can be damaged by inlet air contaminated with volcanic ash. Solid deposits from
any number of sources can collect on engine baffles or other engine surfaces and prevent engine
cooling. Accumulation of deposits on the induction air filter can restrict or block air flow to the
engine and significantly decrease engine power. Contamination of engine oil can cause engine
malfunction and/or failure from abrasive wear.
• Ash on the ground and runways can cause contamination of the engine compartment and
subsequent engine damage during aircraft landing or take-off.
• In the event that flight through volcanic ash clouds or with ash on the ground and subsequent
contamination occurs, Lycoming Engines recommends the following standard actions:
1. Monitor the engine temperature during flight (damaged or blocked cooling baffles or
heavy deposits on engine cooling surfaces can decrease cooling efficiency and cause
engine overheating).
2. If the engine is not operating smoothly in flight, make a safe landing of the aircraft as
soon as possible and isolate faults on the engine.
CAUTION
3. Additional measures could be necessary under specific operating conditions. Refer to the
IO-390-D Series Engine Maintenance Manual for corrective action.
Overspeed
• In engine overspeed, the engine operates above its rated rpm speed (Appendix A). Operation
of an engine above its rated rpm can cause accelerated wear on already stressed components.
Momentary overspeed can occur during a landing attempt, when the propeller governor is in
a lag as the throttle is suddenly opened for a go-around. In fixed wing aircraft, momentary
overspeed is an increase of no more than 10% of rated engine rpm for a period not exceeding
3 seconds.
CAUTION
• Refer to the latest revision of Service Bulletin No. SB-369 for corrective action for engine
overspeed.
• Record all incidents of engine overspeed in the engine logbook, along with the inspection and
any specified corrective action taken per Chapter 05-50 in the IO-390-D Series Engine
Maintenance Manual.
Engine Conditions
Page 44
IO-390-D Series Engine Installation and Operation Manual
DO NOT TOUCH THE VOLCANIC ASH WITH BARE HANDS. DO
NOT USE WATER TO REMOVE THE VOLCANIC ASH.
DO NOT OPERATE AN ENGINE CONTINUOUSLY IN AN
OVERSPEED CONDITION BECAUSE IT CAN WEAR OUT ENGINE
PARTS AND EVENTUALLY CAUSE ENGINE FAILURE.
© 2020 Avco Corporation. All Rights Reserved
March 2020
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