As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOS - FLT 4406 - DURING FLIGHT, CREW REPORTED THE EMERGENCY BUSS WENT INOPERATIVE. AIRCRAFT RETURNED TO BOS AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND JET PACK POWER SUPPLY AT FAULT. POWER PACK WAS REPLACED AND SYSTEM CHECKED NORMAL. (M)