EMB120 FLC HAS A PROB WITH THE L GEAR NOT RETRACTING; HAVING A GEAR DOOR OPEN INDICATION. CHKLISTS WERE RUN AND ACFT RETURNED TO ATL FOR INSPECTION. CAPT CITES CREW FATIGUE AS BEING A FACTOR IN SLOW ASSESSMENT OF THE PROB IN READING OF THE CHKLISTS.

Narrative

CREW DEPARTED ATL WITH FO AS PF. 1ST LEG OF SCHEDULED 2- LEG CONTINUOUS DUTY OVERNIGHT. FOR CAPT; IT WAS 4TH CONSECUTIVE WORK DAY; 2ND CONTINUOUS DUTY TRIP. L MAIN GEAR DID NOT INDICATE COMPLETE RETRACTION AFTER TKOF. RED DISAGREEMENT LIGHTS REMAINED ILLUMINATED. SLIPSTREAM NOISE INDICATED SOME GEAR OR DOOR REMAINED DOWN. CTL FEEDBACK WAS NOTICEABLE BUT MINIMUM. LEVELED ACFT AND NOTIFIED ATC. REQUESTED HEADINGS/TIME TO DIAGNOSE IRREGULARITY AND RUN CHKLIST. CALLED FLT ATTENDANT TO VISUALLY INSPECT L MAIN FROM CABIN AREA. SHE ADVISED GEAR WAS NOT DOWN OR IN SIGHT. IN ACCORDANCE WITH CHKLIST; CYCLED GEAR DOWN AND IMMEDIATELY SHOWED 3 GREEN INDICATION. AFTER ACFT CTL WAS VERIFIED; CHKLIST COMPLETE AND ATC NOTIFIED OF OUR INTENTION TO RETURN; CAPT ENTERED CABIN TO INSPECT/VISUALLY VERIFY PRESENCE OF BOTH MAIN GEAR. NOSEWHEEL TAXI LIGHT PRESENCE VERIFIED NOSE WAS DOWN-LOCKED. VECTORS TO RWY 27L IN ATL; CAPT LANDED ACFT WITHOUT FURTHER INCIDENT. PAX DEPLANED AND CHANGED ACFT. DEPARTED AGAIN WITHIN 1 HR OF INITIAL RETURN. EXTREME FATIGUE SLOWED DOWN/IMPAIRED LOCATING CORRECT CHKLIST AND CAUSED CREW TO ASSUME SOMETHING MISSED DURING PREFLT. CONDITION (MECHANICAL) WAS ACTUALLY DIAGNOSED BY MAINT AS ELECTRICAL MALFUNCTION IN GEAR DOORS. CAPT'S SCHEDULE PREVIOUS DAYS HAD INCLUDED OVER 17 FLT HRS; A TRIP EXTENSION FROM 2 TO 3 DAYS DUE TO ANOTHER MECHANICAL PROB; A FERRY FLT; A PREVIOUS NIGHT'S SCHEDULED HOTEL STOP OF 5 1/4 HRS REDUCED TO 2 1/2 HRS FOR OPERATIONAL DELAYS. CIRCADIAN SLEEP TOTALLY GONE. SLEEP PATTERN DISRUPTION AND ERRATIC SCHEDULING/HVY FLT LOAD RESULTED IN ACUTE FATIGUE. TRYING TO MANAGE SECOND MALFUNCTION IN 2 CALENDAR DAYS. VISION SO BLURRY AND CONCENTRATION SO DIFFICULT THAT EVEN LOCATING/READING PROPER PROC WAS DIFFICULT. HOWEVER; ALL LEGAL UNDER CURRENT FAR 'CREW REST' LIMITS.