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B757-200 captain discovers maintenance allows continued operations of engines at vibration levels at which the flight crew's aom requires the engine to be shut down.
| Attributes | |
| ACN | 742926 |
| Time | |
| Date | 200706 |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : zzzz.artcc |
| State Reference | FO |
| Altitude | msl single value : 37000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zzzz.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| ASRS Report | 742926 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper documentation non adherence : published procedure |
| Independent Detector | other flight crewa |
| Resolutory Action | aircraft : equipment problem dissipated flight crew : overcame equipment problem flight crew : declared emergency |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : manuals |
| Supplementary | |
| Problem Areas | Chart Or Publication Maintenance Human Performance Aircraft |
| Primary Problem | Chart Or Publication |
Narrative:
I had to declare an emergency and return to ZZZ due to excessive vibration levels on the right engine. The vibration levels were between 2.5 and 3.0 at cruise power; but we were able to reduce the level to 2.4 by reducing the power to 1.4 EPR. This setting was maintained for the remainder of the cruise portion of the leg in order to keep the vibration level within limits. After arriving at the gate and discussing the situation via phone with maintenance control; I learned that the maintenance manual allows the aircraft to continue operation for numerous flight cycles with vibration levels up to 3.0; while our QRH emergency procedure requires an engine shutdown if the level cannot be maintained below 2.5. Maintenance control was planning on sending this aircraft right back out to ZZZZ with this condition. I informed maintenance control of our QRH limitation; and that I could not take the aircraft with this issue. He agreed; and took the aircraft OTS. This is a very serious discrepancy between the QRH and the maintenance manual which needs to be rectified as soon as possible.
Original NASA ASRS Text
Title: B757-200 CAPTAIN DISCOVERS MAINTENANCE ALLOWS CONTINUED OPERATIONS OF ENGINES AT VIBRATION LEVELS AT WHICH THE FLT CREW'S AOM REQUIRES THE ENGINE TO BE SHUT DOWN.
Narrative: I HAD TO DECLARE AN EMER AND RETURN TO ZZZ DUE TO EXCESSIVE VIBRATION LEVELS ON THE R ENG. THE VIBRATION LEVELS WERE BTWN 2.5 AND 3.0 AT CRUISE PWR; BUT WE WERE ABLE TO REDUCE THE LEVEL TO 2.4 BY REDUCING THE PWR TO 1.4 EPR. THIS SETTING WAS MAINTAINED FOR THE REMAINDER OF THE CRUISE PORTION OF THE LEG IN ORDER TO KEEP THE VIBRATION LEVEL WITHIN LIMITS. AFTER ARRIVING AT THE GATE AND DISCUSSING THE SIT VIA PHONE WITH MAINT CTL; I LEARNED THAT THE MAINT MANUAL ALLOWS THE ACFT TO CONTINUE OP FOR NUMEROUS FLT CYCLES WITH VIBRATION LEVELS UP TO 3.0; WHILE OUR QRH EMER PROC REQUIRES AN ENG SHUTDOWN IF THE LEVEL CANNOT BE MAINTAINED BELOW 2.5. MAINT CTL WAS PLANNING ON SENDING THIS ACFT RIGHT BACK OUT TO ZZZZ WITH THIS CONDITION. I INFORMED MAINT CTL OF OUR QRH LIMITATION; AND THAT I COULD NOT TAKE THE ACFT WITH THIS ISSUE. HE AGREED; AND TOOK THE ACFT OTS. THIS IS A VERY SERIOUS DISCREPANCY BTWN THE QRH AND THE MAINT MANUAL WHICH NEEDS TO BE RECTIFIED ASAP.
Data retrieved from NASA's ASRS site as of January 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.