TWO MECHANICS REPORT ON EVENTS THAT LED TO A MD-80 AIR TURNBACK AFTER THEY HAD REPLACED THE LH AND RH AIR CONDITIONING WATER SEPARATOR SOCKS AND DEFERRED THE APU FOR HAZE IN CABIN.

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I WAS SENT TO ZZZ1 WITH MR X TO CHANGE THE WATER SOCKS ON ACFT AND DEFER THE APU DUE TO HAZE IN THE CABIN WHEN THE PLANE TAXIED INTO THE GATE. MR X CHANGED THE SOCKS WHILE I HELD THE LIGHT AND THE PRINTED MAINT MANUAL PAGES. WE FOLLOWED THE PROCS PER MAINT MANUAL 21-20-02 STEPS 3-6. WE THEN RAN THE ENGS WITH PACKS RUNNING AT 1.2 EPR TO LEAK CHK THE WATER SEPARATORS AND VERIFY THAT WE DID NOT HAVE A HAZE PROB. I DEFERRED THE APU. THE PLANE WAS BOARDED UP AND ON CLBOUT THE AFT R-HAND LAVATORY SMOKE DETECTOR WENT OFF AND THE AFT CABIN HAD HAZE. ACFT TURNED AROUND AND LANDED BACK IN ZZZ1. IT APPEARED THAT THE R ACM WAS TAKING OIL; SO I DEFERRED THE R-HAND PACK AND THEN WE ASKED THE FLT CREW TO RUN THE ENGS; SO WE COULD RUN THE L-HAND PACK AND CHK FOR HAZE. THE L-HAND PACK WAS ALSO EMITTING A SLIGHT HAZE; SO AT THAT TIME WE CONCLUDED THAT BOTH SYS NOW HAVE OIL IN THEM SO THE FLT WAS CANCELED AND THE ACFT WAS FERRIED BACK TO ZZZ. MAINT SUPVR NOTIFIED MR X THAT HE MAY WANT TO FILL OUT A SAFETY RPT BECAUSE IT IS CONSIDERED AN EVENT AND THEN MR X NOTIFIED ME. QA ALSO ASKED SOME QUESTIONS AS TO WHY WE DIDN'T PERFORM THE 'ALTERNATE PROC;' WHICH ALSO INDICATED THAT THIS MAY BE CONSIDERED AN EVENT. I READ THE ALTERNATE PROC IN ITS ENTIRETY AND AGREE THAT A BURNOUT PROC SHOULD HAVE BEEN DONE AND THAT WE IN FACT MAY BE IN ERROR AS TO THE ACTIONS WE TOOK TO ADDRESS THE DISCREPANCY. THE PREFERRED MAINT MANUAL STEPS WERE FOLLOWED TO SVC THE WATER SEPARATORS. THERE WASN'T ANY SIGN OF OIL IN THE DUCTS TO OR FROM THE SOCKS SO WE FELT THAT THE APU HAD CAUSED THE HAZE AND EVERYTHING WAS FINE AFTER CHANGING THE SOCKS AND DEFERRING THE APU. WE READ AND FOLLOWED STEPS 3-6 BUT DID NOT THOROUGHLY READ STEP 7 SINCE IT IS 'ALTERNATE.' I JUST READ STEP 7 (ALTERNATE PROC) IN ITS ENTIRETY TODAY AND THERE IS A NOTE THAT STATES A BURNOUT RUN SHOULD BE PERFORMED ANY TIME THERE IS HAZE RPTED IN THE CABIN. I DIDN'T FEEL THAT IT WAS NECESSARY TO READ AND PERFORM THE ALTERNATE PROC IF WE WERE ABLE TO FOLLOW THE PREFERRED PROC; BUT SINCE THE DATE OF THE EVENT; I HAVE BEEN INFORMED THAT A MISTAKE WAS MADE AND SHOULD HAVE READ THE ENTIRE SECTION. I RECOGNIZE THIS MISTAKE AND WILL TAKE STEPS TO BE MORE THOROUGH IN THE FUTURE. IN THE FUTURE I WILL READ THE PREFERRED AND ALTERNATE PROCS TO MAKE SURE I DON'T MISS ANY CRUCIAL STEPS. TO PREVENT ANYONE ELSE FROM MAKING THE SAME MISTAKE; I WOULD LIKE TO SEE THE MANUAL REVISED SO THE NOTE THAT REQUIRES THE BURNOUT RUN BE ADDED TO THE PREFERRED METHOD OF WATER SEPARATOR SVCING ALSO (STEP 3). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER ACN # 798328. REPORTER STATED THE 'ALTERNATE PROCEDURE' FOR THE MD-80 REFERRED TO IN THEIR REPORT INCLUDES A MAINT 'NOTE' THAT STATES IF SMOKE OR HAZE OCCURS IN THE CABIN; THE ALTERNATE PROCEDURE IS ALSO REQUIRED. THIS INCLUDES USING A STINGER TYPE PROBE IN THE PNEUMATIC SUPPLY DUCT DURING ENGINE RUNS. BUT THIS 'NOTE' WAS NOT AT THE BEGINNING OF THE PREFERRED PROCEDURE IN THE AMM CHAPTER THEY HAD USED TO ADDRESS THE CABIN HAZE CONDITION. REPORTER STATED THE APU HAD DUMPED ALL IT'S OIL INTO THE APU; WHICH CAUSED THE ORIGINAL HAZE IN THE CABIN DURING THE PREVIOUS TAXI IN TO GATE. WHEN ACFT RETURNED TO GATE FOR THE SAME HAZE CONDITION IN THE CABIN; THEY REALIZED THE APU OIL HAD EVEN CONTAMINATED THE AIR CONDITIONING PNEUMATIC HEAT EXCHANGERS. REPORTER ALSO STATED THE LH AND RH ACM'S; HEAT EXCHANGERS; VALVES AND WATER SEPARATORS AND SOCKS WERE REPLACED LATER; AFTER THE FERRY FLIGHT TO THEIR MAINT BASE. HIS CARRIER HAS REVISED THEIR MANUAL TO INCLUDE THE MAINT 'NOTE' IN THE PREFERRED PROCEDURE SECTION OF THE AMM.