Maintenance error results in in-flight engine shutdown.

Attributes
ACN	139281
Time
Date	199002
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den
State Reference	CO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	139281
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : declared emergency none taken : unable
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

In the process of troubleshooting a torque fluctuation problem on aircraft xx I determined that the compressor bleed valve was sticking. Therefore, I changed it. In the act of changing the bleed valve I inadvertently left off the valve seat, thus causing the valve to stick open necessitating an in-flight shutdown. Mitigating circumstances contributing to this error are as follows: first, it was outside, dark, cold and the airplane had a departure time of less than one hour away. Ergo, I was in a hurry. Second, it was my first bleed valve change on a xa engine and I was unaware of the valve seat. Third, the engine ran perfectly on ground run after completion of the change. These contributing factors in no way justify my error. However, added together they allowed the mistake to go undetected before release for flight. I had changed numerous bleed valves on the xb engine and assumed the xa were the same. In my haste and in the dark I failed to notice the seat on the removed valve. And, the engine ran perfectly on ground check, therefore, I thought everything to be ok. I am deeply grateful the consequences were mo more severe than they were. I have learned much from this incident. Hereafter, I shall assume nothing, and resolve to be more conscientious of proper procedure.

Original NASA ASRS Text

Title: MAINTENANCE ERROR RESULTS IN INFLT ENGINE SHUTDOWN.

Narrative: IN THE PROCESS OF TROUBLESHOOTING A TORQUE FLUCTUATION PROB ON ACFT XX I DETERMINED THAT THE COMPRESSOR BLEED VALVE WAS STICKING. THEREFORE, I CHANGED IT. IN THE ACT OF CHANGING THE BLEED VALVE I INADVERTENTLY LEFT OFF THE VALVE SEAT, THUS CAUSING THE VALVE TO STICK OPEN NECESSITATING AN INFLT SHUTDOWN. MITIGATING CIRCUMSTANCES CONTRIBUTING TO THIS ERROR ARE AS FOLLOWS: FIRST, IT WAS OUTSIDE, DARK, COLD AND THE AIRPLANE HAD A DEP TIME OF LESS THAN ONE HR AWAY. ERGO, I WAS IN A HURRY. SECOND, IT WAS MY FIRST BLEED VALVE CHANGE ON A XA ENG AND I WAS UNAWARE OF THE VALVE SEAT. THIRD, THE ENG RAN PERFECTLY ON GND RUN AFTER COMPLETION OF THE CHANGE. THESE CONTRIBUTING FACTORS IN NO WAY JUSTIFY MY ERROR. HOWEVER, ADDED TOGETHER THEY ALLOWED THE MISTAKE TO GO UNDETECTED BEFORE RELEASE FOR FLT. I HAD CHANGED NUMEROUS BLEED VALVES ON THE XB ENG AND ASSUMED THE XA WERE THE SAME. IN MY HASTE AND IN THE DARK I FAILED TO NOTICE THE SEAT ON THE REMOVED VALVE. AND, THE ENG RAN PERFECTLY ON GND CHK, THEREFORE, I THOUGHT EVERYTHING TO BE OK. I AM DEEPLY GRATEFUL THE CONSEQUENCES WERE MO MORE SEVERE THAN THEY WERE. I HAVE LEARNED MUCH FROM THIS INCIDENT. HEREAFTER, I SHALL ASSUME NOTHING, AND RESOLVE TO BE MORE CONSCIENTIOUS OF PROPER PROC.

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.