Narrative:

Descending out of approximately 12;000 ft into ZZZ; the cabin crew called the cockpit via the interphone chime. The first officer; who was the pilot not flying; answered the call and spoke to the flight attendant. The flight attendant informed the first officer that some of the passenger oxygen masks had dropped from overhead. Rows 11; 13; and 25 (seats D; east; and F) were affected. The first officer relayed the flight attendant's message to me. Both of us began to search for a cause; as no indication of a problem was immediately apparent. After a short time; the first officer found the apparent cause and informed me that his umbrella had inadvertently activated the passenger oxygen mask eject switch. I looked over and saw the guard in the 'up' position; while the switch appeared to be in the 'norm' position. The first officer's umbrella was resting vertically; near the guarded switch. The first officer informed me that he had recently put a manual back into the aircraft library and must have pushed the umbrella in such a manner that it caused the switch to be momentarily activated. The passenger oxygen mask eject switch was placed back into the guarded position. At this point; the aircraft had descended through approximately 10;000 ft. A normal approach and landing followed. As I taxied the aircraft to the gate; the first officer called maintenance control and informed them of the oxygen masks that had dropped in the cabin and the reason for the occurrence. Once the aircraft was parked at the gate; I put the discrepancy in the maintenance logbook.

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Original NASA ASRS Text

Title: Several rows of passenger oxygen masks dropped when the First Officer's umbrella accidentally momentarily activated a B717 passenger Oxygen Mask Eject switch then left it in a normal position.

Narrative: Descending out of approximately 12;000 FT into ZZZ; the cabin crew called the cockpit via the interphone chime. The First Officer; who was the pilot not flying; answered the call and spoke to the Flight Attendant. The Flight Attendant informed the First Officer that some of the passenger oxygen masks had dropped from overhead. Rows 11; 13; and 25 (seats D; E; and F) were affected. The First Officer relayed the Flight Attendant's message to me. Both of us began to search for a cause; as no indication of a problem was immediately apparent. After a short time; the First Officer found the apparent cause and informed me that his umbrella had inadvertently activated the passenger Oxygen Mask Eject Switch. I looked over and saw the guard in the 'up' position; while the switch appeared to be in the 'norm' position. The First Officer's umbrella was resting vertically; near the guarded switch. The First Officer informed me that he had recently put a manual back into the aircraft library and must have pushed the umbrella in such a manner that it caused the switch to be momentarily activated. The passenger Oxygen Mask Eject Switch was placed back into the guarded position. At this point; the aircraft had descended through approximately 10;000 FT. A normal approach and landing followed. As I taxied the aircraft to the gate; the First Officer called Maintenance Control and informed them of the oxygen masks that had dropped in the cabin and the reason for the occurrence. Once the aircraft was parked at the gate; I put the discrepancy in the Maintenance Logbook.

Data retrieved from NASA's ASRS site as of April 2012 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.