Narrative:

During preflight found first officer (first officer) oxygen mask did not test properly. Reset test switch was sticking and mask did not test. First 10 attempts to test the mask resulted in a bad test. I removed and re-stowed the oxygen mask but the mask still did not test properly. Entered the defect into the electronic log book (elb) via ACARS and called maintenance. First mechanic said there was nothing wrong. I showed him exactly what was happening. He got one good test; however when I asked him to test it a second time he refused and said it did not have to be tested more than once. I did not agree. He then asked if I wanted him to replace the mask box. I informed him that it was my responsibility to report the defect and his responsibility to make the necessary repair. I went to perform the exterior walk around. When I returned to my seat I tested the mask again and it did not test properly. I entered another discrepancy in the elb via ACARS. When I explained the problem to the second mechanic; he suggested that only captains could write up the aircraft; because that's how it always worked. I verbalized that his comment was inappropriate and explained again that this was a safety of flight discrepancy that I entered into the elb as required by [company] SOP; and it needed to be addressed. After demonstrating the failed test; the mechanic did agree that the box containing the O2 mask should be replaced. The defect was repaired and signed off and we departed without further delay. However approximately 60 minutes after departure; at FL380; the captain and I arranged for a bathroom break. When I tried to remove the quick donning oxygen mask; the entire mask and box assembly came out as one piece; making it impossible to don the mask quickly. The mechanics did not secure the box to the panel; rendering the quick don feature of the mask useless. In a rapid decompression this would have been a serious safety of flight scenario. I left the mask out of its container for the remainder of the flight for quick access; and we entered the discrepancy in the elb via ACARS. The flight continued to [destination] uneventfully.

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Original NASA ASRS Text

Title: B757 flight crew reported that the First Officer's O2 mask did not test properly.

Narrative: During preflight found First Officer (FO) oxygen mask did not test properly. Reset Test switch was sticking and mask did not test. First 10 attempts to test the mask resulted in a bad test. I removed and re-stowed the oxygen mask but the mask still did not test properly. Entered the defect into the Electronic Log Book (ELB) via ACARS and called maintenance. First mechanic said there was nothing wrong. I showed him exactly what was happening. He got one good test; however when I asked him to test it a second time he refused and said it did not have to be tested more than once. I did not agree. He then asked if I wanted him to replace the mask box. I informed him that it was my responsibility to report the defect and his responsibility to make the necessary repair. I went to perform the exterior walk around. When I returned to my seat I tested the mask again and it did not test properly. I entered another discrepancy in the ELB via ACARS. When I explained the problem to the second mechanic; he suggested that only captains could write up the aircraft; because that's how it always worked. I verbalized that his comment was inappropriate and explained again that this was a safety of flight discrepancy that I entered into the ELB as required by [Company] SOP; and it needed to be addressed. After demonstrating the failed test; the mechanic did agree that the box containing the O2 mask should be replaced. The defect was repaired and signed off and we departed without further delay. However approximately 60 minutes after departure; at FL380; the captain and I arranged for a bathroom break. When I tried to remove the quick donning oxygen mask; the entire mask and box assembly came out as one piece; making it impossible to don the mask quickly. The mechanics did not secure the box to the panel; rendering the quick don feature of the mask useless. In a rapid decompression this would have been a serious safety of flight scenario. I left the mask out of its container for the remainder of the flight for quick access; and we entered the discrepancy in the ELB via ACARS. The flight continued to [destination] uneventfully.

Data retrieved from NASA's ASRS site 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.