Hi,
I have a dual-needle RMI, the Honeywell/Bendix KI229.
The instrument has seen various failures over the 3 years I've had it from new. Just the OBS not turning, just the needles not turning, the whole lot gone. The instrument has been changed and also a 400Hz inverter has been changed.
I now have an intermittent failure which always fixes itself once the aircraft becomes airborne (but never on the ground) so it's probably vibration related. The OBS does not turn but the needles work fine.
The RMI has its own 28V 400Hz inverter and the dealer reckons it is that (again).
But surely the KI229 uses the synchro principle to rotate not just the OBS but also both needles, and the same inverter's failure would freeze the whole instrument?
The HSI, from which the RMI (I am told) gets the heading data) works fine.
I am an electronics engineer but haven't got into avionics much; also obtaining the schematics is a world-class challenge :)
Can anyone suggest where to look?
Peter.
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