Oil Starvation/Sudden Loss Of Oil Pressure - Lycoming YO-233-B2A Maintenance Manual

— Cooling air baffles and/or baffle strip deterioration
— Sudden cool down of the engine that can occur with a rapid descent with
If valve sticking is a problem, refer to the section "Corrective Action for Valve
(4)
Sticking" in Chapter 72-30.
I. Oil Starvation/Sudden Loss of Oil Pressure
(1) To operate correctly at various attitudes, the engine must be supplied with a sufficient
quantity of lubricating oil. Unless there is an adequate quantity of lubricating oil at all
times during flight, loss of oil pressure can occur.
(2) During various attitudes of flight, the risk of oil not covering the inlet to the oil pump
increases as the quantity of oil decreases. In certain attitudes, the oil in the sump cannot
be drawn into the oil pickup line which can cause a momentary loss of oil pressure. If
there is insufficient oil during flight, oil starvation can occur. Yet, not all low oil pressure
incidents result in oil starvation.
(3) Very often a sudden loss of oil pressure is quickly followed by a sudden rise in oil
temperature.
(4) As a preventive measure, before every take-off, complete a check of the engine oil level
as per instructions in "Oil Level Check" in chapter 12-10. Make sure the oil level is at the
specified level shown in the Flight Manual or Pilot Operating Handbook.
NOTICE: Circumstances which cause loss of oil pressure can be different which makes
prediction of the extent of damage to the engine or future engine reliability
difficult. In case of oil pressure loss or engine operation with oil below the
minimum operating level, the most conservative action is to remove the engine,
disassemble, and completely examine all engine components. Any decision to
operate an engine that had loss of oil pressure without an inspection must be the
responsibility of the agency putting the aircraft back into service.
(5) Any time oil pressure falls below the minimum level, identify the root cause as per the
following protocol progressive steps:
(a) Complete the check of the oil level in the oil sump. Drain the oil if necessary to
measure the oil quantity.
(b) If the oil level is sufficient, complete the check of the oil pressure indication system
accuracy. If the oil pressure gage is not operating correctly, replace it.
(c) Examine oil hose connections for leaks. Tighten any loose connections and look for
leaks. Replace leaking oil hoses.
(d) Examine the oil suction screen at the oil sump and the oil filter for blockage or metal
deposits. If metal or blockage is found, remove the material and identify the origin of
material and correct the root cause.
(e) Examine the oil pump for malfunction. Replace the oil pump if it is not operating
correctly.
(f) If the oil pressure indication system is operating correctly and there has been
confirmation that oil pressure loss/oil starvation has occurred, remove and
disassemble the engine and perform a complete inspection.
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reduced power or engine shutdown without sufficient engine cooling.
YO-233-B2A Engine Maintenance Manual
TEO-540-A1A Engine Maintenance Manual
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February 2021