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A B757-200 released for service had all passenger oxygen masks drop when battery bus was pwred. Masks repacked. Dropped again with external power removed.
| Attributes | |
| ACN | 593620 |
| Time | |
| Date | 200309 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : parked |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 593620 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : improper documentation non adherence : published procedure non adherence : far |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | performance deficiency : non compliance with legal requirements performance deficiency : logbook entry performance deficiency : testing |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Maintenance Human Performance Chart Or Publication Aircraft |
| Primary Problem | Maintenance Human Performance |
Narrative:
When external power was applied to the airplane, or possibly the battery switch, all oxygen masks on the airplane dropped. This occurred after first arriving at the airplane during initial preflight. Contract maintenance repacked all the masks. Later, the mechanic was instructed to disconnect external power by pulling the power cord from the airplane. When the power cord was pulled, the oxygen masks dropped a second time. Question: when the power is off the airplane if the oxygen mask switch is pressed, does it go to the 'on' position and stay there? Do the masks then deploy when power is applied? Some action was taken before the airplane was returned to service. Were any of the components that were removed defective?
Original NASA ASRS Text
Title: A B757-200 RELEASED FOR SVC HAD ALL PAX OXYGEN MASKS DROP WHEN BATTERY BUS WAS PWRED. MASKS REPACKED. DROPPED AGAIN WITH EXTERNAL PWR REMOVED.
Narrative: WHEN EXTERNAL PWR WAS APPLIED TO THE AIRPLANE, OR POSSIBLY THE BATTERY SWITCH, ALL OXYGEN MASKS ON THE AIRPLANE DROPPED. THIS OCCURRED AFTER FIRST ARRIVING AT THE AIRPLANE DURING INITIAL PREFLT. CONTRACT MAINT REPACKED ALL THE MASKS. LATER, THE MECH WAS INSTRUCTED TO DISCONNECT EXTERNAL PWR BY PULLING THE PWR CORD FROM THE AIRPLANE. WHEN THE PWR CORD WAS PULLED, THE OXYGEN MASKS DROPPED A SECOND TIME. QUESTION: WHEN THE PWR IS OFF THE AIRPLANE IF THE OXYGEN MASK SWITCH IS PRESSED, DOES IT GO TO THE 'ON' POS AND STAY THERE? DO THE MASKS THEN DEPLOY WHEN PWR IS APPLIED? SOME ACTION WAS TAKEN BEFORE THE AIRPLANE WAS RETURNED TO SVC. WERE ANY OF THE COMPONENTS THAT WERE REMOVED DEFECTIVE?
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.