What was found
OPERATOR REPORTED EXCESSIVE NOISE IN HEADSET FROM RADIOS. TROUBLESHOOTING FOUND NOISE DISAPPEARED WITH ALTERNATOR OFF LINE. FURTHER INVESTIGATION FOUND MAGNETIC COMPASS DEVIATION OF 20 DEGREES WITH ALTERNATOR ON LINE. ELECTRICAL SYSTEM WIRING GROUNDS, BONDING AND SHIELDING CHECKED. IN LINE NOISE FILTERS HAD NO AFFECT ON NOISE EMISSION. INSTALLED THREE ALTERNATORS, SN: A-160134, A-160136, AND A-160130 WITH NO CHANGES IN NOISE OR COMPASS DEVIATION. INSTALLED ALTERNATIVE MFG/ELECTRO SYSTEMS ALTERNATOR, PART NUMBER E3FF10300AA, WHICH ELIMINATED RADIO NOISE AND MAGNETIC COMPASS DEVIATION.