What was found
CAPTAIN'S OXYGEN MASK DOES NOT STOP FLOW OF OXYGEN WHEN IN USE.(<P>SWAPPED LEFT SUPERNUMERARY SEAT MASK (OFF PART: P/N MC10-08-114, S/N B119143) WITH CAPTAIN MASK (OFF PART: P/N MC10-08-109, S/N SE63145) IAW B767 AMM 35-11-51. TRANSFERRED LEFT SUPERNUMERARY SEAT TO MDDR 120447 PER DDG 25-25-03, CAT 'D', DUE: 09-MAR-2020.</P><P>LP 1229251 - M2: SUPERNUMERARY LEFT SEAT OXYGEN MASK HAS BEEN REMOVED AND REPLACED IAW B767 -300 AMM 35-11-51. OPS CHECK OK, NO DEFECTS FOUND AT THIS TIME. THIS CLEARS MDDR 120447. PLACARDS REMOVED AND MCC NOTIFIED. </P>)