A B737-300 was dispatched and returned to the field after maintenance due to #2 engine pneumatic sys...

Attributes
ACN	411421
Time
Date	199808
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mht
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	other
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	411421
Person 2
Affiliation	company : air carrier
Function	other personnel other
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Aircraft xyz air carrier returned because of a #2 engine bleed air problem. I performed (along with another technician) a pneumatic inspection and check of the #2 engine bleed system the night before the aircraft air returned. When I left work, the test of the #2 engine bleed system was working within limits of work card. Callback conversation with reporter revealed the following information: the reporter stated the aircraft had a #2 engine pneumatic report and troubleshooting revealed the precooler valve was the problem and the valve was replaced. The reporter said that sometime during the replacement of the precooler valve the pressure regulator shutoff valve lockout mechanism became engaged and locked the valve closed. The reporter stated no engine run was performed to test the engine pneumatic system after the precooler valve replacement. The reporter said the pressure regulator and shutoff valve locking mechanism lock bolt must have been loose and the valve locking block must have been bumped and pushed into the locking slot.

Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED AND RETURNED TO THE FIELD AFTER MAINT DUE TO #2 ENG PNEUMATIC SYS INOP DUE TO A VALVE INADVERTENTLY LOCKED CLOSED.

Narrative: ACFT XYZ ACR RETURNED BECAUSE OF A #2 ENG BLEED AIR PROB. I PERFORMED (ALONG WITH ANOTHER TECHNICIAN) A PNEUMATIC INSPECTION AND CHK OF THE #2 ENG BLEED SYS THE NIGHT BEFORE THE ACFT AIR RETURNED. WHEN I LEFT WORK, THE TEST OF THE #2 ENG BLEED SYS WAS WORKING WITHIN LIMITS OF WORK CARD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT HAD A #2 ENG PNEUMATIC RPT AND TROUBLESHOOTING REVEALED THE PRECOOLER VALVE WAS THE PROB AND THE VALVE WAS REPLACED. THE RPTR SAID THAT SOMETIME DURING THE REPLACEMENT OF THE PRECOOLER VALVE THE PRESSURE REGULATOR SHUTOFF VALVE LOCKOUT MECHANISM BECAME ENGAGED AND LOCKED THE VALVE CLOSED. THE RPTR STATED NO ENG RUN WAS PERFORMED TO TEST THE ENG PNEUMATIC SYS AFTER THE PRECOOLER VALVE REPLACEMENT. THE RPTR SAID THE PRESSURE REGULATOR AND SHUTOFF VALVE LOCKING MECHANISM LOCK BOLT MUST HAVE BEEN LOOSE AND THE VALVE LOCKING BLOCK MUST HAVE BEEN BUMPED AND PUSHED INTO THE LOCKING SLOT.

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.

A B737-300 was dispatched and returned to the field after maintenance due to #2 engine pneumatic system inoperative due to a valve inadvertently locked closed.