A maintenance inspector was informed; after he had signed-off a logbook item stating 'crew O2 turned...

Narrative:

A B747-400 aircraft was on the ramp at a contract maintenance repair station facility. The [flight] crew was in the flight deck. I asked the first officer (first officer) to verify that there was adequate oxygen flow through his mask. He pressed the button and held it for about ten seconds. Oxygen continued to flow at a normal rate. I was satisfied that the crew oxygen (O2) was turned 'on' because of the duration that the oxygen was flowing. I did not physically verify that the crew oxygen bottle was turned 'on'. Assuming that the bottle was turned 'on'; I entered this statement in the aircraft maintenance log corrective action block; 'crew O2 turned on' and signed the mechanic signature/certificate # block. The next day I received a call; telling me the B747-400 aircraft had diverted because of a crew oxygen light. When the aircraft landed a mechanic discovered that the crew O2 bottle [valve] was turned 'off'. That was when I realized my failure to physically verify that the crew O2 bottle was turned 'on' caused this event. I should never have assumed that the crew O2 bottle was turned 'on' based on oxygen flow from the crew mask alone. No exceptions. No shortcuts. The bottle must always be physically verified that it is turned 'on' by checking the bottle valve handle.

Original NASA ASRS Text

Title: A Maintenance Inspector was informed; after he had signed-off a Logbook item stating 'Crew O2 turned On'; a B747-400 cargo aircraft had diverted due to a Crew Oxygen (O2) light illuminating in flight. A Downline station Mechanic found the Crew O2 bottle valve handle 'Closed'.

Narrative: A B747-400 aircraft was on the ramp at a Contract Maintenance Repair Station facility. The [Flight] crew was in the flight deck. I asked the First Officer (F/O) to verify that there was adequate oxygen flow through his mask. He pressed the button and held it for about ten seconds. Oxygen continued to flow at a normal rate. I was satisfied that the Crew Oxygen (O2) was turned 'On' because of the duration that the oxygen was flowing. I did not physically verify that the Crew Oxygen bottle was turned 'On'. Assuming that the bottle was turned 'On'; I entered this statement in the Aircraft Maintenance Log Corrective Action block; 'Crew O2 turned on' and signed the Mechanic signature/Certificate # block. The next day I received a call; telling me the B747-400 aircraft had diverted because of a Crew Oxygen light. When the aircraft landed a Mechanic discovered that the Crew O2 bottle [valve] was turned 'Off'. That was when I realized my failure to physically verify that the Crew O2 bottle was turned 'On' caused this event. I should never have assumed that the Crew O2 bottle was turned 'On' based on oxygen flow from the crew mask alone. No exceptions. No shortcuts. The bottle must always be physically verified that it is turned 'On' by checking the bottle valve handle.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	997005
Time
Date	201202
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Aircraft 1
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Component
Aircraft Component	Oxygen System/Crew
Person 1
Function	Inspector
Qualification	Maintenance Powerplant Maintenance Airframe
Experience	Maintenance Inspector 16 Maintenance Technician 19
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

A maintenance inspector was informed; after he had signed-off a logbook item stating 'crew O2 turned on'; a B747-400 cargo aircraft had diverted due to a crew oxygen (O2) light illuminating in flight. A downline station mechanic found the crew O2 bottle valve handle 'closed'.