912ULS tacho and mag drop puzzles

Thanks Peter

My kill wires are individually screened. At the engine the screens go to an ignition unit mounting screw with a link from it to the engine block. The kill wires go to L & R on the key switch. The ground lug in the centre of the switch has a wire to the -ve busbar (composite airframe!) to which the screens also go. The busbar is directly linked to the battery feed cable (battery is behind seats) terminal post on the firewall from which there is the main bond to the engine block. I actually think the screens should only be grounded at one end but Rotax say ground both ends.

Mike

Two pics of the same fully functioning installation:

Mag drop solved.

Watching a video of the test run, you can see from blade flicker and hear that there is a slight drop. However with only the digital tach, reading in 120rpm steps and flickering an increment or two, and stood outside the a/c in the noise and buffet, I simply wasn't aware of it!

Sorry guys! 

As to the tacho, I think it has to be an instrument fault undisclosed by seller.

This probably will not solve anything but I pass it along just to be complete.

Rotax Tachometer Installation SI

Thanks Bill.

It says "repair of the instrument is not possible."

A challenge!