What was found
WHEN SETTING UP AIRCRAFT THE EMERG LIGHT ON MESSAGE DOESNT INITIALLY COME ON BUT AFTER A FEW MINUTES OF CHARGING THE LIGHT DOES COME ON COMPLETEING THE TEST. IT APPEARS THAT ONE OF THE POWER PACKS MAYBE LOSING THE CHARGE IF IT IS OFF FOR AN EXTENDED. PERIOD OF TIME. IT WAS CHECKED UPON LANDING AND WORKING FINE. R & R NR 1 POWER SUPPLY & REPLACED WITH A NEW UNIT IAW AMM 33-53-09. OPS CHKD GOOD. R & R NR 2 POWER SUPPLY & REPLACED WITH A TESTED UNIT IAW AMM 33-53-11. OPS CHKD GOOD. R & R NR 3 POWER SUPPLY & REPLACED WITH A NEW UNIT IAW AMM 33-53-11. OPS CHKD GOOD. R & R NR 4 POWER SUPPLY & REPLACED WITH A NEW UNIT IAW AMM 33-53-13. OPS CHECK GOOD.