As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS AFTER TAKEOFF, FLAPS WOULD NOT RETRACT FROM FLAP 1. AFTER LANDING BELOW 80 KTS, PESU LIGHT ILLUMINATED. EXTENDED FLAPS BY ALT FLAP EXTENTION. MAINTENANCE ACCOMPLISHED FIM 27-51-00-810-822/823. REMOVED AND REPLACED FSEU IAW AMM 27-51-01-000-801. NO FAULT NOTED. GROUND TEST OK. ALSO PERFORMED DFCS FLAP TEST. SYSTEM GROUND TEST OK.