Narrative:

This was a problem with the intrusion resistant door between the cabin and cockpit. The captain left the cockpit for a physiological break. The first officer had his oxygen mask on and the cockpit door was closed and locked. When the captain signaled the first officer to unlock the door, the first officer complied but the captain was unable to open the door. After three attempts, the first officer had to get out of his seat and open the door. The door had been properly pre flted and functioned properly on the ground prior to departure. Callback conversation with reporter revealed the following information: the reporter stated the door was checked prior to departure and checked ok in all modes. The reporter said in flight with full pressurization some slight distortion of the bulkhead and door frame occurs causing binding between the door and the door frame. The reporter stated this is a common problem and generally overcome with a little extra force on the 2-INCH circular door knob. The reporter said in this event the door knob was too small to exert any force to pull the door open when unlocked. The reporter stated what is needed and previously suggested is a heavier handle to pull the door open when unlocked.

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Original NASA ASRS Text

Title: AN MD10 AT FL350, THE CAPT RPTS UNABLE TO REENTER THE COCKPIT USING NORMAL MODE OF UNLOCKING. FO REQUIRED TO LEAVE SEAT TO UNLOCK.

Narrative: THIS WAS A PROB WITH THE INTRUSION RESISTANT DOOR BETWEEN THE CABIN AND COCKPIT. THE CAPT LEFT THE COCKPIT FOR A PHYSIOLOGICAL BREAK. THE FO HAD HIS OXYGEN MASK ON AND THE COCKPIT DOOR WAS CLOSED AND LOCKED. WHEN THE CAPT SIGNALED THE FO TO UNLOCK THE DOOR, THE FO COMPLIED BUT THE CAPT WAS UNABLE TO OPEN THE DOOR. AFTER THREE ATTEMPTS, THE FO HAD TO GET OUT OF HIS SEAT AND OPEN THE DOOR. THE DOOR HAD BEEN PROPERLY PRE FLTED AND FUNCTIONED PROPERLY ON THE GND PRIOR TO DEP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE DOOR WAS CHECKED PRIOR TO DEP AND CHECKED OK IN ALL MODES. THE RPTR SAID IN FLT WITH FULL PRESSURIZATION SOME SLIGHT DISTORTION OF THE BULKHEAD AND DOOR FRAME OCCURS CAUSING BINDING BETWEEN THE DOOR AND THE DOOR FRAME. THE RPTR STATED THIS IS A COMMON PROB AND GENERALLY OVERCOME WITH A LITTLE EXTRA FORCE ON THE 2-INCH CIRCULAR DOOR KNOB. THE RPTR SAID IN THIS EVENT THE DOOR KNOB WAS TOO SMALL TO EXERT ANY FORCE TO PULL THE DOOR OPEN WHEN UNLOCKED. THE RPTR STATED WHAT IS NEEDED AND PREVIOUSLY SUGGESTED IS A HEAVIER HANDLE TO PULL THE DOOR OPEN WHEN UNLOCKED.

Data retrieved from NASA's ASRS site as of July 2007 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.