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VDO oil pressure sender.

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  • VDO oil pressure sender.

    The only item which concerned me on my now one year old QuikR, was a falling oil pressure. At delivery 2.9 bar and 2.3 bar twelve month later. As I am Rotax trained I investigated by fitting oil pressure gauge on oil pump replacing the installed VDO sender. Pressure reading now 5 bar cold and 4 bar at operating temp. Amazing difference so I informed P&M of my findings, no reaction.
    Further investigation revealed that my engine is latest type of Rotax 912S, having 10mm metric fine thread in oil pump housing suitable for the originally delivered Rotax solid state sender. As I had ordered a VDO instrument package which P&M purchases from SKYDRIVE. They had taken off solid state sensor and fitted the VDO sender, however this has 1/8 NPT thread which is a tapered form having same pitch as the 10mm metric fine thread. I was horrified that an aircraft section S manufacturer would do this. Admittingly, no oil leaks, but thread is only having a point contact and not supported correctly on length, probably allowing for the large bulky VDO sender to vibrate. P&M advised no reaction.
    This situation had to be rectified and as aircraft out of guarantee, although it could be argued that this is installed fault on delivery and P&M liable. I am not a vindictive person and I wish for them to succeed as the aircraft is a stunning flying creation, to which I would agree is the best flexwing in the world.
    Reading the Rotax installation guide the new solid state sender requires gauge which reads current flow, instead of the resistance type on the VDO. AVIASPORT mentioned in guide, looking the most suitable to fit in 52mm hole in dashboard, this was sourced directly from Spain. P&M sold me again the removed solid state pressure sensor and special connection with 3 m lead at their special price. Simple install, engine run up for test, for the first time immediate indication of oil pressure showing 5 bar, then dropping to 4 bar for operation. It is now reassuring that oil pressure is correctly indicated as ROTAX had originally intended.