A B737-300 WAS DISPATCHED IN NON COMPLIANCE WITH THE P5 COCKPIT FORWARD OVERHEAD INST PANEL UNLOCKED AND NOT SECURED.

Narrative

WAS TROUBLESHOOTING A STANDBY HYD PUMP WHICH WAS CONTINUALLY RUNNING WITH ACFT GND PWR ON AND ALL HYD RELATED SWITCHES OFF. DROPPED DOWN FLT DECK P5 OVERHEAD PANEL TO GAIN ACCESS TO THE FLT CTL MODULE. THOUGHT FLT CTL MODULE MIGHT BE AT FAULT; SO GOT A SVCABLE MODULE AND SLAVED IT IN. DETERMINED EXISTING FLT CTL MODULE WAS GOOD. REINSTALLED ORIGINAL AND FOUND A SHUTOFF VALVE IN WHEEL WELL TO BE AT FAULT. ADVISED OUR A&P'S THAT VALVE WAS TO BE CHANGED. WENT BACK TO CABIN; LATCHED P5 OVERHEAD PANEL TO 'SAFETY POS' BUT FAILED TO SECURE ZEUS FASTENERS(2) TO THOROUGHLY SECURE PANEL IN PLACE. OMITTED THIS DUE TO ATTEMPTING TO TRY TO HAVE ACFT READY FOR XB20 DEP/TRIP. THIS PROB AROSE AT LAST MIN; AT AROUND XA15; WHEN PWR WAS BROUGHT ON ACFT FOR CLEANERS. UPON ARRIVING IN TO WORK ON OCT/THU/02; FOUND IN COMPANY E-MAIL THAT THE MAINT CTLR AT THE DOWN LINE STATION (ZZZ1) WAS CALLED ON PHONE BY THE CAPT FLYING TRIP OF THIS ACFT THAT HE DISCOVERED; UPON ARRIVING AT ZZZ1; (I ASSUME) OR DURING FLT; THAT THE PANEL WAS NOT FULLY SECURED AS REQUIRED -- THAT ONLY SAFETY LATCH WAS HOLDING P5 IN PLACE.