Narrative:

Aircraft was given takeoff clearance from teb runway 24. All checklists were completed and the takeoff was initiated. The takeoff roll was normal and uneventful. At rotation; all systems indicated normal operations. After establishing a positive rate of climb; the landing gear was retracted and at 400 ft AGL; the flaps were retracted. As the flaps were retracting a loud bang and the sound of air was heard. A noticeable odor of something hot was entering the cabin. At that time I informed the first officer to advise ATC that we may need to return to teb. ATC gave us a vector. I then noticed the emergency press on light illuminated on the annunciator panel. ATC climbed us to 2000 ft. Realizing that there was no need to declare an emergency I advised ATC that we needed vectors to run checklists and evaluate the situation. The checklist instructed the crew to turn off the emergency press and then select the bleed air to the normal position. If the pressurization system functions normally; and does not activate the emergency press on light; then the flight may be continued. After we selected the normal position; the system functioned normal. We then asked ATC to allow us to step climb to check the pressurization system operation. I then made the decision to continue the flight and lower our cruising altitude from 34000 ft to 24000 ft. I decided to fly lower just in case the pressurization system failed. The flight was continued and no other pressurization system malfunction occurred. After evaluating the events I began to realize that I should have declared an emergency; but at the time of the malfunction; my main focus was to fly the airplane. We were assigned a departure from teb that instructed the flight to climb to 1500 ft then at 4.5 DME from teb climb to 2000 ft. I did not climb to 2000 ft until instructed by ATC. During the initial system malfunction; I asked for a vector from ATC for a possible return to teb. I do not believe that the level off at 1500 ft and then a climb to 2000 ft at a certain DME fix is needed. A climb directly to 2000 ft would make the departure more efficient and less complicated particularly during an emergency or system malfunction event. The air cycle machine (acm) on the cessna citation can shutdown and go into shut down mode and trigger the emergency press for an overheat of the acm. This can be caused by extended taxi or extended hold short times which are standard at teb. Cessna could advise the crew to shut down the acm if extended ground times are expected to help prevent acm overheat.

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Original NASA ASRS Text

Title: CE550 FLT CREW HAS PRESSURIZATION ANOMALY DEPARTING ON THE TEB 5 AND FAILS TO CLB TO 2000 FT UNTIL INSTRUCTED TO DO SO BY N90 CTLR.

Narrative: ACFT WAS GIVEN TKOF CLRNC FROM TEB RWY 24. ALL CHKLISTS WERE COMPLETED AND THE TKOF WAS INITIATED. THE TKOF ROLL WAS NORMAL AND UNEVENTFUL. AT ROTATION; ALL SYSTEMS INDICATED NORMAL OPERATIONS. AFTER ESTABLISHING A POSITIVE RATE OF CLB; THE LNDG GEAR WAS RETRACTED AND AT 400 FT AGL; THE FLAPS WERE RETRACTED. AS THE FLAPS WERE RETRACTING A LOUD BANG AND THE SOUND OF AIR WAS HEARD. A NOTICEABLE ODOR OF SOMETHING HOT WAS ENTERING THE CABIN. AT THAT TIME I INFORMED THE FO TO ADVISE ATC THAT WE MAY NEED TO RETURN TO TEB. ATC GAVE US A VECTOR. I THEN NOTICED THE EMER PRESS ON LIGHT ILLUMINATED ON THE ANNUNCIATOR PANEL. ATC CLBED US TO 2000 FT. REALIZING THAT THERE WAS NO NEED TO DECLARE AN EMER I ADVISED ATC THAT WE NEEDED VECTORS TO RUN CHKLISTS AND EVALUATE THE SITUATION. THE CHKLIST INSTRUCTED THE CREW TO TURN OFF THE EMER PRESS AND THEN SELECT THE BLEED AIR TO THE NORMAL POSITION. IF THE PRESSURIZATION SYSTEM FUNCTIONS NORMALLY; AND DOES NOT ACTIVATE THE EMER PRESS ON LIGHT; THEN THE FLT MAY BE CONTINUED. AFTER WE SELECTED THE NORMAL POSITION; THE SYSTEM FUNCTIONED NORMAL. WE THEN ASKED ATC TO ALLOW US TO STEP CLB TO CHK THE PRESSURIZATION SYSTEM OP. I THEN MADE THE DECISION TO CONTINUE THE FLT AND LOWER OUR CRUISING ALT FROM 34000 FT TO 24000 FT. I DECIDED TO FLY LOWER JUST IN CASE THE PRESSURIZATION SYSTEM FAILED. THE FLT WAS CONTINUED AND NO OTHER PRESSURIZATION SYSTEM MALFUNCTION OCCURRED. AFTER EVALUATING THE EVENTS I BEGAN TO REALIZE THAT I SHOULD HAVE DECLARED AN EMER; BUT AT THE TIME OF THE MALFUNCTION; MY MAIN FOCUS WAS TO FLY THE AIRPLANE. WE WERE ASSIGNED A DEP FROM TEB THAT INSTRUCTED THE FLT TO CLB TO 1500 FT THEN AT 4.5 DME FROM TEB CLB TO 2000 FT. I DID NOT CLB TO 2000 FT UNTIL INSTRUCTED BY ATC. DURING THE INITIAL SYSTEM MALFUNCTION; I ASKED FOR A VECTOR FROM ATC FOR A POSSIBLE RETURN TO TEB. I DO NOT BELIEVE THAT THE LEVEL OFF AT 1500 FT AND THEN A CLB TO 2000 FT AT A CERTAIN DME FIX IS NEEDED. A CLB DIRECTLY TO 2000 FT WOULD MAKE THE DEP MORE EFFICIENT AND LESS COMPLICATED PARTICULARLY DURING AN EMER OR SYSTEM MALFUNCTION EVENT. THE AIR CYCLE MACHINe (ACM) ON THE CESSNA CITATION CAN SHUTDOWN AND GO INTO SHUT DOWN MODE AND TRIGGER THE EMER PRESS FOR AN OVERHEAT OF THE ACM. THIS CAN BE CAUSED BY EXTENDED TAXI OR EXTENDED HOLD SHORT TIMES WHICH ARE STANDARD AT TEB. CESSNA COULD ADVISE THE CREW TO SHUT DOWN THE ACM IF EXTENDED GND TIMES ARE EXPECTED TO HELP PREVENT ACM OVERHEAT.

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.