Constant Speed Prop

DSC_5854.jpgInteresting units these… all the more so when ya get to pull them apart, and yes the grease was handy 🙂 This one is a recent MLG failure victim (Chieftian if I remember correctly), quite a nice Hartzell in its working days…dsc_5856.jpg

Propeller construction may consist of an aluminum “clam-shell” hub where the hub captures the blades, or a steel hub “spider” design where the blades are clamped to a hub . The blades may be made from an aluminum forging or from either Kevlar 49® or Carbon based fabrics or unidirectional tapes. The composite blades would additionally incorporate a leading edge erosion sheath to protect the blade from both abrasion (sand) and erosion (water) as well as offer an external conductive for a lightning strike.

The pitch control typically comes from a hydraulic fly-ball governor mounted on the engine. The governor senses whether the engine/propeller is running at the correct RPM and either supplies or maintains oil flow to the propeller, or drains oil to the engine sump. Of course, it is very important that the engine-mounted governor be properly matched to the propeller for proper pitch change command and response. The governor may or may not be supplied by the propeller manufacturer; however, it is necessary to ensure the propeller manufacturer has approved the governor for use with its propeller. In addition to controlling the propeller, this governor typically contains a pump that increases the oil pressure to a higher level than that which the engine supplies to a value sufficient to control the propeller.

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