FLC OPERATED ACFT WHEN IT HAD NOT BEEN PROPERLY SIGNED OFF AS AIRWORTHY AFTER A REQUIRED INSPECTION.

Narrative

AFTER OVERNIGHTING AT A LCL MAINT STATION; WE ARRIVED AT THE ACFT FOR AN EARLY MORNING DEP. I BEGAN MY PREFLT ACTIVITIES AND DISCOVERED THAT LCL MAINT HAD NOT RETURNED THE LOGBOOK TO THE ACFT YET (A COMMON SIT). AT ABOUT 10 MINS PRIOR TO SCHEDULED DEP TIME; I ASKED THE FO TO CALL OPS AND ASK MAINT TO BRING THE ACFT MAINT LOG OUT TO US. I RECEIVED THE LOGBOOK ABOUT 5-7 MINS PRIOR TO DEP TIME. I NOTED THAT LCL MAINT HAD PERFORMED A ROUTINE DAILY (24 HR) CHK AS REQUIRED; A FULL PWR TKOF HAD BEEN DONE WITHIN PRESCRIBED TIME LIMITS; SEVERAL MEL'S OVER THE LAST FEW DAYS HAD BEEN PROPERLY CLRED; AND REFERRING TO THE PREVIOUS LOGBOOK (SINCE THE CURRENT BOOK WAS STARTED VERY RECENTLY) CHKED FOR AN 'AIRWORTHINESS' SIGNOFF ABOUT 6 DAYS AGO. EVERYTHING APPEARED IN ORDER SO WE DEPARTED. ENRTE I STARTED TO ENTER OUR FLT INTO THE LOGBOOK; AND WHILE REVIEWING PREVIOUS PAGES AGAIN; I NOTICED AN INSPECTION HAD BEEN DONE BY ANOTHER MAINT BASE A FEW DAYS PRIOR. THIS PARTICULAR INSPECTION IS GENERALLY ACCOMPANIED BY A SIGNOFF IN AN 'AIRWORTHINESS CERTIFICATION' BOX. THE INSPECTION WAS SIGNED AS COMPLETE BUT THE AIRWORTHINESS BOX WAS NOT. UPON ARR AT DEST (A HVY MAINT STATION) I BROUGHT MY CONCERN TO THE ATTN OF MAINT AND WAS INFORMED THAT THAT PARTICULAR INSPECTION REQUIRED A SIGNATURE IN THE AIRWORTHINESS BOX. THE OMISSION OF A SIGNATURE BY THE MECH REPRESENTED A TECHNICAL LEGALITY QUESTION. BEING ONE OF A NUMBER OF PF THAT ACFT SINCE THAT INSPECTION; THE QUESTION OF LEGALITY HAS BECOME A PROB FOR ME AS WELL AS THE COMPANY.