Date: 201411
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Oxygen System/Crew
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Human Factors; Equipment / Tooling
Primary problem: Human Factors

Narrative: Was at the fuel pit fueling up the line truck; received a call to go to Gate A to service oxygen on a CRJ-200 aircraft. Arrived at the scene and opened up the rear tail gate [of the line truck]. I saw one bottle secured to the bed. It was green in color; with no visible warning sign that I can recall. I noticed a steel braided line attached to the regulator that was wrapped to the tail gate. I did not see the service end. I looked around and found the service kit in the flip top. Enclosed was a regulator and braided line attached. Instead of removing the existing regulator; I swapped line and serviced the aircraft with 120 psi of gas. First day back to work; late afternoon; after getting back to the gate; I installed what I thought was a missing bottle of nitrogen [in the Line truck]. After further inspection I found that the bottle that was already installed in the truck was nitrogen and not oxygen. I immediately notified my Manager of the issue. I believe when I looked in the tail gate I saw a Green bottle and didn't see any obvious abnormalities. I assumed the steel braided line was the same type we used in the hangar on the oxygen servicing bottle. The Bottle didn't have a different regulator like we had on the high pressure bottle; but yet the same color and similar design. Noticed four days later as the oxygen bottles used for hangar servicing. [Recommend] Better placard and warning signs around all gas bottles. [And] More distinctive regulators use for each type (color). Servicing at gate.

Callback: Reporter stated the shorter steel braided hose that was connected to the regulator he pulled out of the flip top compartment in the Line truck was the regulator for Oxygen bottles. Nitrogen and Oxygen regulators have different size connections (fittings) for attaching to the different bottles. The flexible steel braided service lines however; can be connected to either regulator. Since the bottle in the truck was green and he did not want to unravel the longer hose that was already connected to that bottle regulator to service the Crew oxygen; he decided to disconnect the longer line and use the shorter line from the regulator in the flip top. He never gave any thought to changing or checking the bottle regulator; especially since the bottle was green and he could see what remained of a label showing '..gen'; as in oxygen. Reporter stated he was off for several days; but on his first day back he realized his mistake. He was also informed at that time that his air carrier was in fact just starting to get Oxygen and Nitrogen bottles in different shades of green. He has been a Line Mechanic for his air carrier for 15 years and green bottles always meant 'Oxygen'. No information had been passed down to mechanics about the color coded bottles. Since his incident and the potential for flight crew(s) becoming incapacitated during flight; his air carrier now requires all nitrogen bottles to be black and the oxygen to remain green. The CRJ-200 was grounded; all the pilot oxygen masks were replaced and the Oxygen System purged. Only nitrogen bottles are allowed in their Line trucks and the oxygen bottles are now on carts located at the Terminal gates.



Synopsis: Four days after servicing crew oxygen on a CRJ-200 aircraft; a Line Aircraft Maintenance Technician (AMT) realizes the green bottle he used was actually a nitrogen bottle. Aircraft was grounded shortly after.