Narrative:

On climb out we transferred the bleeds per the climb checklist. Upon transfer; an unfamiliar odor; acrid in nature; began and quickly intensified. Upon calling the flight attendant in the back; it was discovered that the odor was very strong as well and a haze had developed. The decision was made to return to ZZZ. An emergency was not declared although a precautionary landing was performed and the crash fire rescue equipment trucks activated. Upon landing; we taxied off the runway and stopped on the taxiway. Crash fire rescue equipment personnel boarded the aircraft to search for possible fire. Odor was still very strong and the crash fire rescue equipment people all smelled it; too. No fire was detected and the passenger were deplaned on the taxiway. Many were checked out by medical personnel. The passenger were then bussed to the terminal and the crew stayed with the aircraft while it was towed to the remote parking area. The aircraft was put back in service just before we took it over for this flight. It had come from maintenance where hydraulic problems had been fixed. The maintenance personnel that inspected the aircraft after our landing saw that it was wet under the hydraulic reservoir #1. It is believed; at this point; that we all inhaled and have been affected by skydrol hydraulic fluid. The flight attendant is coughing and lost her voice. The captain and myself will get checked out for exposure to skydrol.callback conversation with reporter revealed the following information: a very acrid odor was experienced after switching pneumatic bleed from the auxiliary power unit to the engine bleed system. Cabin attendant reported odor very strong and a haze had filled the cabin. The flight was diverted to the departure station and met by crash fire rescue equipment. On the ground; the odor was still present.

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Original NASA ASRS Text

Title: A CRJ200 ON CLBOUT AT 6000 FT. WHEN THE PNEUMATIC BLEEDS WERE SWITCHED FROM AUX POWER UNIT TO ENGS; A STRONG ODOR AND HAZE FILLED THE CABIN AND COCKPIT. DIVERTED TO DEP ARPT.

Narrative: ON CLBOUT WE TRANSFERRED THE BLEEDS PER THE CLB CHKLIST. UPON TRANSFER; AN UNFAMILIAR ODOR; ACRID IN NATURE; BEGAN AND QUICKLY INTENSIFIED. UPON CALLING THE FLT ATTENDANT IN THE BACK; IT WAS DISCOVERED THAT THE ODOR WAS VERY STRONG AS WELL AND A HAZE HAD DEVELOPED. THE DECISION WAS MADE TO RETURN TO ZZZ. AN EMER WAS NOT DECLARED ALTHOUGH A PRECAUTIONARY LNDG WAS PERFORMED AND THE CFR TRUCKS ACTIVATED. UPON LNDG; WE TAXIED OFF THE RWY AND STOPPED ON THE TXWY. CFR PERSONNEL BOARDED THE ACFT TO SEARCH FOR POSSIBLE FIRE. ODOR WAS STILL VERY STRONG AND THE CFR PEOPLE ALL SMELLED IT; TOO. NO FIRE WAS DETECTED AND THE PAX WERE DEPLANED ON THE TXWY. MANY WERE CHKED OUT BY MEDICAL PERSONNEL. THE PAX WERE THEN BUSSED TO THE TERMINAL AND THE CREW STAYED WITH THE ACFT WHILE IT WAS TOWED TO THE REMOTE PARKING AREA. THE ACFT WAS PUT BACK IN SVC JUST BEFORE WE TOOK IT OVER FOR THIS FLT. IT HAD COME FROM MAINT WHERE HYDRAULIC PROBS HAD BEEN FIXED. THE MAINT PERSONNEL THAT INSPECTED THE ACFT AFTER OUR LNDG SAW THAT IT WAS WET UNDER THE HYDRAULIC RESERVOIR #1. IT IS BELIEVED; AT THIS POINT; THAT WE ALL INHALED AND HAVE BEEN AFFECTED BY SKYDROL HYDRAULIC FLUID. THE FLT ATTENDANT IS COUGHING AND LOST HER VOICE. THE CAPT AND MYSELF WILL GET CHKED OUT FOR EXPOSURE TO SKYDROL.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: A VERY ACRID ODOR WAS EXPERIENCED AFTER SWITCHING PNEUMATIC BLEED FROM THE AUX POWER UNIT TO THE ENG BLEED SYSTEM. CABIN ATTENDANT REPORTED ODOR VERY STRONG AND A HAZE HAD FILLED THE CABIN. THE FLT WAS DIVERTED TO THE DEP STATION AND MET BY CFR. ON THE GND; THE ODOR WAS STILL PRESENT.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.