DA 62 AFM Airplane Description
Pressure Accumulator:
The pressure accumulator is a nitrogen oil type. It is connected to the gearbox oil circuit
via an electric valve at the accumulator, which is operated with the ENGINE MASTER
switch.
When the ENGINE MASTER switch is set to ON the valve is opened. During engine
operation the accumulator makes sure that enough oil pressure is available even if the
oil feed by the gearbox oil pump is decreasing due to negative acceleration. The hydraulic
pressure keeps the propeller pitch angle below the start lock position, or moves the
propeller blades beyond the start lock position.
Feathering:
To feather the propeller the engine must be shut down with the appropriate ENGINE
MASTER switch. This will open the electric governor valve. All oil will flow back from the
propeller hub, allowing the blades to move into the feathered pitch position. At the same
time, the electric valve at the pressure accumulator closes, and the oil pressure is restored
in the accumulator.
Feathering is only possible at propeller speeds above 1300 RPM.
CAUTION
If the engine is shut down below 1300 RPM, the propeller
pitch remains below the start lock position. In this case, the
speed must be increased to increase the propeller RPM.
Doc. No. 11.01.05-E Rev. 0 11-Jan-2019 Page 7 - 33
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