Narrative:

Ship was released to the line with no open write-ups after 2 days in a 'letter check.' first officer performed an extensive and attentive preflight because of this fact. After pushback, we started both engines for taxi (first flight of the day, short taxi and heavy weight). We began to taxi and once clear of the congested ramp area, started the flight control check in anticipation of the taxi check. I had used the tiller in right turns only to get clear of the area and was surprised to find the left rudder completely jammed. I set the parking brake and discovered that even 'standing' on the rudder, I could only get about 1 inch of travel. We also found that the control wheel was extremely stiff in all directions. When displacing the ailerons, the control wheel would remain displaced and not return to neutral without using the same force required to displace it. The control wheel also had random movements, from twitching to full forward and aft deflection to free movement of about 4 inches. All hydraulic pressure and quantity gauges read normal and all low pressure lights on the overhead panel were extinguished. In short, there were no indications that any system was inoperative. We left both engines running and moved no switches until maintenance came out to the aircraft and was able to see what we had encountered. Maintenance cycled the hydraulic pumps and even with all hydraulic power removed and the engines now shut down, the flight controls were still extremely stiff though slightly less so than before. We were towed back to the gate and wrote up the indications in the logbook. Later that day, we were surprised to find the corrective action for the aircraft was to de-power the airplane and reset circuit breakers. The maintenance personnel we spoke with were just as surprised as we were that this problem would be electrical. They suggested that it sounded more like the manual shutoff valves had been left closed during maintenance thereby creating a 'hydraulic lockout' of the flight controls. These valves, which are normally closed during a letter check to change filters, are located downstream of the flight control pressure sensors, and therefore all cockpit indications would be normal. We had thought that the B737 rudder problems had been fixed with the hydraulic pressure reducer modification. Do we now have a larger problem affecting the entire flight control system? If it was only the manual shutoff valves, and was not properly documented as such, we have unnecessarily created a situation where once again, the pilots cannot trust the flight control system of an already infamous aircraft (and we cannot trust that the corrective action in the book was really the true fix). But if our flight controls can be reset by depwring the aircraft and resetting circuit breakers, I would really like to know exactly which circuit breakers they are and confirm that when pulled, they produce the same results we encountered. This information would be invaluable if this situation ever happened again, or god forbid, in the air. Callback conversation with reporter revealed the following information: the reporter stated there was no way a group or series of circuit breakers could be out and missed on the preflight cockpit check. The reporter said after engine start with a and B hydraulics pressurized and all flight control low pressure warning lights out, the flight controls would not check normal. The reporter stated the signoff is suspect and it is believed by the flight crew and others the flight control maintenance valves were closed in the heavy check and not reopened before delivery to the gate. The reporter said this is a poor maintenance practice and should be corrected.

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Original NASA ASRS Text

Title: A B737-200 ON FLT CTL CHK AFTER PUSHBACK FOUND ALL FLT CTLS INOP. CAPT SUSPECTS MAINT SIGNOFF OF CORRECTIVE ACTION NOT CORRECT.

Narrative: SHIP WAS RELEASED TO THE LINE WITH NO OPEN WRITE-UPS AFTER 2 DAYS IN A 'LETTER CHK.' FO PERFORMED AN EXTENSIVE AND ATTENTIVE PREFLT BECAUSE OF THIS FACT. AFTER PUSHBACK, WE STARTED BOTH ENGS FOR TAXI (FIRST FLT OF THE DAY, SHORT TAXI AND HEAVY WT). WE BEGAN TO TAXI AND ONCE CLR OF THE CONGESTED RAMP AREA, STARTED THE FLT CTL CHK IN ANTICIPATION OF THE TAXI CHK. I HAD USED THE TILLER IN R TURNS ONLY TO GET CLR OF THE AREA AND WAS SURPRISED TO FIND THE L RUDDER COMPLETELY JAMMED. I SET THE PARKING BRAKE AND DISCOVERED THAT EVEN 'STANDING' ON THE RUDDER, I COULD ONLY GET ABOUT 1 INCH OF TRAVEL. WE ALSO FOUND THAT THE CTL WHEEL WAS EXTREMELY STIFF IN ALL DIRECTIONS. WHEN DISPLACING THE AILERONS, THE CTL WHEEL WOULD REMAIN DISPLACED AND NOT RETURN TO NEUTRAL WITHOUT USING THE SAME FORCE REQUIRED TO DISPLACE IT. THE CTL WHEEL ALSO HAD RANDOM MOVEMENTS, FROM TWITCHING TO FULL FORWARD AND AFT DEFLECTION TO FREE MOVEMENT OF ABOUT 4 INCHES. ALL HYD PRESSURE AND QUANTITY GAUGES READ NORMAL AND ALL LOW PRESSURE LIGHTS ON THE OVERHEAD PANEL WERE EXTINGUISHED. IN SHORT, THERE WERE NO INDICATIONS THAT ANY SYS WAS INOP. WE LEFT BOTH ENGS RUNNING AND MOVED NO SWITCHES UNTIL MAINT CAME OUT TO THE ACFT AND WAS ABLE TO SEE WHAT WE HAD ENCOUNTERED. MAINT CYCLED THE HYD PUMPS AND EVEN WITH ALL HYD PWR REMOVED AND THE ENGS NOW SHUT DOWN, THE FLT CTLS WERE STILL EXTREMELY STIFF THOUGH SLIGHTLY LESS SO THAN BEFORE. WE WERE TOWED BACK TO THE GATE AND WROTE UP THE INDICATIONS IN THE LOGBOOK. LATER THAT DAY, WE WERE SURPRISED TO FIND THE CORRECTIVE ACTION FOR THE ACFT WAS TO DE-POWER THE AIRPLANE AND RESET CIRCUIT BREAKERS. THE MAINT PERSONNEL WE SPOKE WITH WERE JUST AS SURPRISED AS WE WERE THAT THIS PROB WOULD BE ELECTRICAL. THEY SUGGESTED THAT IT SOUNDED MORE LIKE THE MANUAL SHUTOFF VALVES HAD BEEN LEFT CLOSED DURING MAINT THEREBY CREATING A 'HYD LOCKOUT' OF THE FLT CTLS. THESE VALVES, WHICH ARE NORMALLY CLOSED DURING A LETTER CHK TO CHANGE FILTERS, ARE LOCATED DOWNSTREAM OF THE FLT CTL PRESSURE SENSORS, AND THEREFORE ALL COCKPIT INDICATIONS WOULD BE NORMAL. WE HAD THOUGHT THAT THE B737 RUDDER PROBS HAD BEEN FIXED WITH THE HYD PRESSURE REDUCER MODIFICATION. DO WE NOW HAVE A LARGER PROB AFFECTING THE ENTIRE FLT CTL SYS? IF IT WAS ONLY THE MANUAL SHUTOFF VALVES, AND WAS NOT PROPERLY DOCUMENTED AS SUCH, WE HAVE UNNECESSARILY CREATED A SIT WHERE ONCE AGAIN, THE PLTS CANNOT TRUST THE FLT CTL SYS OF AN ALREADY INFAMOUS ACFT (AND WE CANNOT TRUST THAT THE CORRECTIVE ACTION IN THE BOOK WAS REALLY THE TRUE FIX). BUT IF OUR FLT CTLS CAN BE RESET BY DEPWRING THE ACFT AND RESETTING CIRCUIT BREAKERS, I WOULD REALLY LIKE TO KNOW EXACTLY WHICH CIRCUIT BREAKERS THEY ARE AND CONFIRM THAT WHEN PULLED, THEY PRODUCE THE SAME RESULTS WE ENCOUNTERED. THIS INFO WOULD BE INVALUABLE IF THIS SIT EVER HAPPENED AGAIN, OR GOD FORBID, IN THE AIR. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING INFO: THE RPTR STATED THERE WAS NO WAY A GROUP OR SERIES OF CIRCUIT BREAKERS COULD BE OUT AND MISSED ON THE PREFLT COCKPIT CHK. THE RPTR SAID AFTER ENG START WITH A AND B HYDS PRESSURIZED AND ALL FLT CTL LOW PRESSURE WARNING LIGHTS OUT, THE FLT CTLS WOULD NOT CHK NORMAL. THE RPTR STATED THE SIGNOFF IS SUSPECT AND IT IS BELIEVED BY THE FLT CREW AND OTHERS THE FLT CTL MAINT VALVES WERE CLOSED IN THE HVY CHK AND NOT REOPENED BEFORE DELIVERY TO THE GATE. THE RPTR SAID THIS IS A POOR MAINT PRACTICE AND SHOULD BE CORRECTED.

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.