Narrative:

In ZZZ; the captain called and indicated that he couldn't set the landing elevation in the automatic pressure controller. I discussed the discrepancy with maintenance control and the electro-pneumatic outflow valve was suspected to be the root cause. I decided to defer the valve per MEL 21-16 and faxed amm references EMB145 amm task 21-31-03-000-801-a and task 21-31-03-400-801-a which are the procedures for the removal and installation of the electro-pneumatic outflow valve. The procedures for securing the outflow valve are stated and illustrated in MEL 21-16. All that information was received by our contract mechanic. While climbing to 10000 ft; the crew notified dispatch/maintenance that they had no pressurization. Upon landing in ZZZ; local maintenance determined that the outflow was secured incorrectly. With coordination between the crew; dispatch; and moc; the aircraft diverted to ZZZ. Upon landing in ZZZ; I asked supervisor to check the electro-pneumatic outflow valve to see if the contract mechanic secured it per MEL 21-16. It was secured in the wrong position. ZZZ maintenance cleared the MEL. The contract mechanic secured the outflow valve in the open position; instead of the closed position. This prohibited the aircraft from pressurizing. He failed to follow the published procedures that were provided to him. The emb MEL reference 21-16 figure 21-3 detail 'a' should be more clearly depicted as to where the safety wire should be secured. Additionally; a note stating that the bellows should not be depressed when securing the outflow valve would help prevent this from happening again. Callback conversation with reporter revealed the following information: reporter stated the cabin pressure controller was not functioning in the automatic mode; only in the manual mode. Part of the MEL deferral procedure was to safety wire the outflow valve in the closed position. But the outflow valve on the emb-145 is normally spring loaded closed on the ground; as compared to many other aircraft where the outflow valve is normally open on the ground. This confused the contract maintenance mechanic; who ended up wiring the outflow valve in the open position; contrary to emb's maintenance manual procedures and diagrams. Reporter stated the MEL reference 21-16 should be more clearly depicted as to where the safety wire should be secured. Also. A note stating the bellows should not be depressed when securing the outflow valve; would help prevent this from happening again.

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Original NASA ASRS Text

Title: A MAINTENANCE CONTROLLER REPORTS AN EMB-145 WAS NOT ABLE TO PRESSURIZE IN FLIGHT AFTER CONTRACT MAINTENANCE INADVERTENTLY SAFETY WIRED THE OUTFLOW VALVE IN THE 'OPEN' INSTEAD OF THE 'CLOSED' POSITION. AIRCRAFT DIVERTED.

Narrative: IN ZZZ; THE CAPT CALLED AND INDICATED THAT HE COULDN'T SET THE LNDG ELEVATION IN THE AUTO PRESSURE CONTROLLER. I DISCUSSED THE DISCREPANCY WITH MAINT CTL AND THE ELECTRO-PNEUMATIC OUTFLOW VALVE WAS SUSPECTED TO BE THE ROOT CAUSE. I DECIDED TO DEFER THE VALVE PER MEL 21-16 AND FAXED AMM REFERENCES EMB145 AMM TASK 21-31-03-000-801-A AND TASK 21-31-03-400-801-A WHICH ARE THE PROCS FOR THE REMOVAL AND INSTALLATION OF THE ELECTRO-PNEUMATIC OUTFLOW VALVE. THE PROCS FOR SECURING THE OUTFLOW VALVE ARE STATED AND ILLUSTRATED IN MEL 21-16. ALL THAT INFO WAS RECEIVED BY OUR CONTRACT MECH. WHILE CLBING TO 10000 FT; THE CREW NOTIFIED DISPATCH/MAINT THAT THEY HAD NO PRESSURIZATION. UPON LNDG IN ZZZ; LOCAL MAINT DETERMINED THAT THE OUTFLOW WAS SECURED INCORRECTLY. WITH COORDINATION BETWEEN THE CREW; DISPATCH; AND MOC; THE ACFT DIVERTED TO ZZZ. UPON LNDG IN ZZZ; I ASKED SUPVR TO CHK THE ELECTRO-PNEUMATIC OUTFLOW VALVE TO SEE IF THE CONTRACT MECH SECURED IT PER MEL 21-16. IT WAS SECURED IN THE WRONG POSITION. ZZZ MAINT CLRED THE MEL. THE CONTRACT MECH SECURED THE OUTFLOW VALVE IN THE OPEN POSITION; INSTEAD OF THE CLOSED POSITION. THIS PROHIBITED THE ACFT FROM PRESSURIZING. HE FAILED TO FOLLOW THE PUBLISHED PROCS THAT WERE PROVIDED TO HIM. THE EMB MEL REF 21-16 FIGURE 21-3 DETAIL 'A' SHOULD BE MORE CLEARLY DEPICTED AS TO WHERE THE SAFETY WIRE SHOULD BE SECURED. ADDITIONALLY; A NOTE STATING THAT THE BELLOWS SHOULD NOT BE DEPRESSED WHEN SECURING THE OUTFLOW VALVE WOULD HELP PREVENT THIS FROM HAPPENING AGAIN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE CABIN PRESSURE CONTROLLER WAS NOT FUNCTIONING IN THE AUTO MODE; ONLY IN THE MANUAL MODE. PART OF THE MEL DEFERRAL PROCEDURE WAS TO SAFETY WIRE THE OUTFLOW VALVE IN THE CLOSED POSITION. BUT THE OUTFLOW VALVE ON THE EMB-145 IS NORMALLY SPRING LOADED CLOSED ON THE GROUND; AS COMPARED TO MANY OTHER AIRCRAFT WHERE THE OUTFLOW VALVE IS NORMALLY OPEN ON THE GROUND. THIS CONFUSED THE CONTRACT MAINTENANCE MECHANIC; WHO ENDED UP WIRING THE OUTFLOW VALVE IN THE OPEN POSITION; CONTRARY TO EMB'S MAINTENANCE MANUAL PROCEDURES AND DIAGRAMS. REPORTER STATED THE MEL REF 21-16 SHOULD BE MORE CLEARLY DEPICTED AS TO WHERE THE SAFETY WIRE SHOULD BE SECURED. ALSO. A NOTE STATING THE BELLOWS SHOULD NOT BE DEPRESSED WHEN SECURING THE OUTFLOW VALVE; WOULD HELP PREVENT THIS FROM HAPPENING AGAIN.

Data retrieved from NASA's ASRS site as of May 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.