RETURN LAND WITH ACFT EQUIP PROB.

Narrative

PREFLT HAD BEEN NORMAL. ALL CHKLISTS ACCOMPLISHED. ON TKOF ROLL; CAPT'S WINDOW OPENED ON LGT. INITIAL CLBOUT WAS IN ACCORDANCE WITH SID; THEN AFTER APPROX 2000 FT MSL; I REDUCED PWR/CLB RATE AND SPD TO 160 KIAS IN ORDER TO COMMUNICATE. NOISE LEVEL WAS DEAFENING. REQUESTED AND RECEIVED ATC CLRNC FOR LEVEL OFF AT 4000 FT AND RADAR VECTORS FOR RETURN TO LGA. APCH AND LNDG UNEVENTFUL. THE WINDOW APPEARED TO BE CLOSED AND LOCKED DURING PREFLT. THE FORWARD HANDLE WAS CLOSED AND LOCKED AND WE HAD A GOOD 'CLOSED' INDICATION AT THE TOP. THE 'WINDOW NOT CLOSED' DECAL WAS NOT VISIBLE AND THE REAR ELBOW APPEARED TO BE 90 DEGS; BUT IN FACT THE OVER-CTR LOCK HAD BEEN LEFT A FRACTION OF AN INCH SHORT OF 90 DEGS BY WHOMEVER CLEANED THE WINDOWS THE NIGHT BEFORE. THIS IS VERY INSIDIOUS AND COULD ONLY HAVE BEEN DETECTED BY OPENING THE WINDOW AND RECLOSING IT. THIS IS A DEFECTIVE DESIGN AND INCIDENTS SUCH AS THIS ONE WILL CONTINUE TO HAPPEN ON THE WDB/LGT ACFT. A SQUAT SWITCH IS NEEDED ON THE OVER- CTR LOCK THAT IS TIED IN WITH THE WARNING LIGHTS.