Flightcom iNova User Manual page 13

If a high pitch whine is only present with the engine running and varies with RPM
It is from alternator or generator noise on the aircraft power bus. This may be an
indication of a weak aircraft battery or an alternator with a bad diode. You may be
able to remedy the problem with a commercially available alternator noise filter
connected in series with the intercom power lead.
If all else fails
If you cannot get the unit to function at all, try checking it out in another aircraft.
Do not return the unit for repair without first contacting our service department.
Please have as much information as possible available when you call.
List the symptoms you've encountered as well as any corrective actions or
troubleshooting you have tried. You may contact us at service@flightcom.net
To return the unit for repair you MUST call and get an RMA number and
packing/shipping instructions from our service department at 800-432-4342,
or 503-684-8229.
We reserve the right to refuse delivery on any incoming packages that are not clearly
marked with an RMA number. Warranty claims require that a dated sales receipt or
proof of purchase be provided when requested and that your warranty card has been
filled out and returned to Flightcom. Repair charges for non-warranty service will be
estimated when you call for an RMA.