Three mechanics report why a safety pin was not installed in an Oxygen Generator that was removed with a Passenger Service Unit (PSU) from a CRJ-900 aircraft and inadvertently shipped to a repair Vendor. The PSU was removed due to a Flight Attendant's 'Call Button' that would not reset because of an internal electrical circuit board shorting-out.
Synopsis
Three mechanics report why a safety pin was not installed in an Oxygen Generator that was removed with a Passenger Service Unit (PSU) from a CRJ-900 aircraft and inadvertently shipped to a repair Vendor. The PSU was removed due to a Flight Attendant's 'Call Button' that would not reset because of an internal electrical circuit board shorting-out.
Narrative
I was called over to help Mechanic Y with an [overhead] Passenger Service Unit (PSU); he was having problems with the Safety pin and Lanyard pin [for the Oxygen Generator canister]. When I got on the CRJ-900 aircraft; the PSU was on his lap with only one pin in [the oxygen generator]; just enough 'not to go off'. I took the PSU from him and removed him and the PSU from the aircraft. I worked on it with him on the table. Corrected the problem; but in the process broke the safety pin (when we Removed/Replaced (R/R) the PSU; we usually take the safety pin from the new [PSU's Oxygen generator] and install the pin on the old [removed generator] for Unserviceable Tag purposes). I was under the impression that we had none [no extra safety pins]. The Mechanic asked me how we should do [fill-out] the Unserviceable Tag [section]. I said label [Tag] to where Stores (Parts) could see and read that there is no safety pin installed; and they will not ship until we get one installed. The Mechanic did so. At this point I asked if they need anymore help and I left to the next aircraft. I think this event occurred for two reasons:One; we assumed that we had no safety pins; because we used the pin from the new one (PSU); and Two; we assumed that Stores/Parts would read the caution on the front of the PSU and not ship the part with no pin installed. One suggestion would be to make a Task Card for Removal and Replacement (R/R) of PSU and have a Supervisor or Inspector task block [sign-off] to check to make sure safety pin is installed in [oxygen] generator before putting the part on the Unserviceable Tag shelf. Also; have Stores double-check and inspect parts before sending out. The PSU was shipped out even after Maintenance labeled the PSU. The Vendor's shop detected that the O2 Generator had no safety pin installed after Stores shipped it out.
Second reporter narrative
I; Mechanic Y [working Avionics]; was troubleshooting a problem with the Flight Attendant's 'Call Button' on a CRJ-900 aircraft. A bad Passenger Service Unit (PSU) was discovered and a new PSU was ordered and installed on the aircraft. I was having a difficult time removing both the safety pin from the new Oxygen Generator [canister] and installing the safety pin into the old oxygen generator on the bad PSU. On both occasions the main release [Activation] pin attached to the lanyard was starting to come out; as well as the safety pin which made me very nervous. I asked Mechanic Z to help and go get my Maintenance Lead [Mechanic X]. The Lead came over and we took the PSU out of the aircraft to work the issue on a bench outside the aircraft. It was a precarious situation and took several sets of hands and about twenty minutes to finally get the safety pin out of the new PSU while ensuring the main release [Activation] pin stayed in place. I then installed the new PSU in the aircraft. By this time the safety pin had become so bent; twisted and distorted that it was useless and would not install in the safety pin hole of the oxygen generator on the bad PSU. I personally did not try to order a new safety pin but was under the impression that we did not have any in stock. My Lead said to write a statement on the unit's [Unserviceable Tag] so that all could read saying; 'CAUTION' safety pin was NOT installed'; which we did. I took it over to the Stores shelf for turn-in but assumed it would not ship until the safety pin issue was rectified. I believe this event occurred due to my lack of communication with Stores personnel about the unsafe condition of this PSU/Oxygen Generator and how serious it was. AND in hindsight; I should have put something through that safety pin hole in lieu of the proper pin such as a cotter pin or a piece of safety wire. I got too involved in the installation and Operational (Ops) Check of the new PSU and did not follow through on the proper safety and turn-in procedures of the old PSU/Oxygen Generator. The part was turned in to the Vendor for repair and the discrepancy was discovered at the Vendor. The solution I have is to treat an Unserviceable Tag part just like a Yellow Tag part; especially when there a safety issue concerned.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.