"THE De HAVILLAND HYDROMATIC AIRSCREW / INSTALLATION" WWII AIRCRAFT PROPELLER FILM 75764

About

This Royal Air Force ground crew educational film "The DeHavilland Hydromatic Airscrew" describes the installation of that propeller, which entered production in the late 1930s and was used during WWII on many different aicraft. The Hydromatic Air Screw consists of three main assemblies: the barrel and blade assembly, the distributor valve housing with its oil conductor sleeve, and the dome assembly, which are carefully installed in sequence. The constant speed unit is mounted behind the air screw and driven by a quill shaft, with a special gasket ensuring a secure joint. During assembly, precise alignment and proper lubrication of components, including splines and oil seals, are crucial. The air screw nut is tightened to a specific torque, and the distributor valve housing is secured with a left-hand thread and locking wire to prevent loosening. Before mounting the dome, the blades are feathered using a torque bar, and the dome assembly is carefully aligned and fastened. After installation, engine runs are conducted to check and adjust the air screw operation, including filling the dome with oil, verifying blade movement across pitch settings, and ensuring RPM limits are met using the constant speed governor. Feathering and unfeathering procedures are tested to confirm proper functionality, with attention to oil pressure effects that may cause occasional unfathering after operation. The reliability of the system depends heavily on skilled craftsmanship during both manufacturing and installation.

0:00 – Introduction to the three main assemblies of the DeHavilland Hydromatic Air Screw: barrel and blade assembly, distributor valve housing with its oil conductor sleeve, and the dome assembly.

1:18 – Constant speed unit fitted to the engine crankcase behind the air screw, driven by a quill shaft.

1:34 – Use of special gasket between crankcase and constant speed unit

2:07 – Cleaning and preparing barrel and blade assembly splines

3:21 – Aligning splines carefully when offering up the gearbox

4:44 – Assembling split cone and tightening air screw nut to specified torque

5:35 – Fitting snap ring and greasing distributor valve housing joint washer and oil conductor sleeve.

6:06 – Marking joint face of distributor valve housing

7:14 – Adding second washer if housing does not pull evenly

7:59 – Explanation of thread directions

8:44 – Turning blades to full feathered position before mounting dome

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