So, leakage test finished with good result.

After the movie is made I did not change anything on the plane, now, 24 hours later the legs are still ”IN”. So leakage test is also oké

Reliability has a lot to do with complexity and amount of components, that’s the reason I prefer pneumatic above electric retracts. Also fail safe is easy to realize.
For me the retracted position is as important as the "tract", I prefer belly landings outside the field or when there isn't enough length , normally without damage.

In the industrial instrumentation in the past we did use a lot of pneumatic equipment; measuring instruments, analog controllers and valves, calculation systems etc. Some brands: Foxboro, Bristol, Honeywell, Siemens, Moore.
It isn’t strange we also did see pneumatic control systems in our modeling in the past, read about Karlheinz Stegmaier and Omu. Pneumatic equipment was used in 1960 and 1962 during world championships pattern flying. In 1962 there were still 3 pneumatic systems used.

More to come

Cees