https://peertube.dngr.us/videos/watch/83bca061-92f3-4bbe-ae72-a3dc58b571f9 Support Our Channel : https://www.patreon.com/PeriscopeFilm 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 9:43 – Oiling oil seal rings on distributor valve housing and checking ring gaps. 10:14 – Ensuring stop lugs on rotating cam contact pitch stops; piston fully back and cams fully feathered. 10:52 – Removing dome plug and inserting special handling bar 11:45 – Engaging dome retaining nut and tightening with special spanner to carry gear preload and oil seal compression load. 13:02 – Locking dome securing nut with grub screw to prevent unscrewing. 13:33 – Before air screw operation, blades turned by hand to fine pitch position to check dome installation. 14:08 – Checking blade movement against degree markings; meshing errors indicated by pitch errors. 14:30 – Inserting and locking dome plug with lock wire. 15:40 – Aircraft wheeled out for engine running and air screw adjustments. 16:02 – Use of auxiliary storage batteries 16:29 – Starting engine at max RPM position, then moving air screw lever to minimum RPM until revolution stabilizes, indicating dome filled with oil. 17:11 – Exercising air screw control lever through full range to ensure all air replaced by oil 17:47 – Moving air screw control to max RPM and opening throttle to takeoff boost 18:25 – Overswing and recovery time during throttle changes 19:02 – Bringing constant speed lever back to minimum RPM and checking RPM needle follows lever until governing reached (~2000 RPM). 19:45 – Adjustments to constant speed governor made if max RPM exceeds or is below limits, using stop screws behind protective cover. 20:29 – Procedure for adjusting max RPM stop: engine run at takeoff boost 21:47 – For low governed RPM, unscrewing stop one turn and measuring RPM increase; adjusting accordingly. 22:46 – Large multi-engine aircraft may have hydraulic control on constant speed units; adjustments easier. 23:37 – Feathering switch pressed at ~1000 RPM to turn blades to feathered position 24:06 – Feathering button throws out after ~10 seconds; engine stopped to verify full feather. 24:29 – Unfeathering 25:17 – Air screw may unfeather after reaching feathered position without pilot action due to residual oil pressure—normal behavior, not occurring in flight. This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD and 2k. For more information visit http://www.PeriscopeFilm.com Source: https://www.youtube.com/watch?v=fvCmQAetyag Mirrored from Periscope Film (https://www.youtube.com/@PeriscopeFilm) Fri, 12 Jun 2026 03:37:53 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://peertube.dngr.us https://peertube.dngr.us/lazy-static/avatars/41a6fee9-7f57-42d0-a5fc-5db4f1af2e31.png https://peertube.dngr.us/videos/watch/83bca061-92f3-4bbe-ae72-a3dc58b571f9 All rights reserved, unless otherwise specified in the terms specified at https://peertube.dngr.us/about and potential licenses granted by each content's rightholder.