What was found
DURING A MANEUVERS TRAINING FLIGHT UNDER PART 91 WE EXPERIENCED A LOW ACUITY ELECTRICAL EMERGENCY. WHILE PREPARING FOR THE RNAV 35 INTO BEND BOTH SIDES VOLTS AND AMPS INDICATIONS RED X’ED WITHOUT ANY G100 ECAS OR EIS SYSTEM MESSAGE DENOTING A FAILURE. WE INITIATED AN IMMEDIATE RETURN TO THE AIRPORT AND LANDED SAFELY. ON FINAL BOTH PFD AND MFD FLICKERED BUT CAME BACK. ALSO, OF NOTE BOTH OF US NOTED AN INTERMITTENT HIGH PITCHED SQUEALING BEEPING. IN OUR HEADSETS THROUGHOUT THE LATTER HALF OF THE FLIGHT BUT SAW NO MESSAGES ASSOCIATED WITH THE NOISE. AIRCRAFT GROUNDED FOR FURTHER EXAMINATION.