A Lead Mechanic and Line Mechanic report installation of a Captain's oxygen (O2) mask that was not 'effective' for their B757-200 aircraft.
Synopsis
A Lead Mechanic and Line Mechanic report installation of a Captain's oxygen (O2) mask that was not 'effective' for their B757-200 aircraft.
Narrative
I received a call from Maintenance Control regarding a crew oxygen mask discrepancy on a B757-200 aircraft. Upon arrival at aircraft [I] spoke to Captain who advised that his oxygen mask would not test. After a brief time for troubleshooting; found Captain's oxygen mask storage box to be suspect. After acquiring relative maintenance documents; I removed both aforementioned oxygen mask and storage box to obtain part numbers as to facilitate replacement serviceable parts/components. Upon parts arrival at gate; I verified part number on [the] serviceable tag and installed both components (I ordered an oxygen mask as a precaution). I then verified the operation of both box and mask; including a leak check at previously displaced fitting. All checked good per maintenance manual criteria. At this point I released the aircraft for service.During the input of pertinent data in my company's maintenance computer system; the oxygen mask that I had ordered and subsequently installed was flagged as being an incorrect part number for this aircraft. Mask part number removed from Captains position was XXYY-107. Part Number I installed was XXYY-107. However; in accordance with the company's Illustrated Parts Manual (IPM); the part number should have been XXYY-108. As the aircraft had already departed; I was not in a position to remedy this. Contact was immediately made with Maintenance Control and Engineering to advise them of this problem. The correct part number mask was installed in the Captain's position at ZZZ a [day later].
Second reporter narrative
During the outbound launch [departure]; I received a call from Maintenance Control that a B757-200 aircraft had a Captain's oxygen (O2) mask that would not test. I dispatched an Aircraft Maintenance Technician (AMT) to the aircraft to check it out. Upon arrival at aircraft; Technician X discovered that in fact the O2 mask would not test. He tried swapping mask from the First Officer's side and it still would not test. He determined that the storage box was at fault.He called me with the part number of the mask and box that he removed. I checked our parts system for both parts and we had them in our stock. I placed both on order and the system alerted me that the mask's company part number was not effective for that aircraft. This happens all the time in our parts system; so I overrode the system and placed the mask on order. Normally we do that a lot and then put the Illustrated Parts Catalog (IPC) reference in the maintenance system to clear the maintenance log item out. The aircraft departed to ZZZ with no delay. During the final action [clearing] process; Technician X discovered [that] indeed the mask was the wrong part number for that aircraft. He installed a XXYY-107; which [was the same part number] he had removed; it should have been a XXYY-108. We called Maintenance Control and informed them of the situation; they immediately notified the down-line station and they corrected the problem. During all of our research after the event; we discovered that on all of our other fleet types of McDonnell/Douglas and Airbus aircraft that the XXYY-107 and the XXYY-108 are interchangeable.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.