B777-200
Maintenance Airframe
Communication Breakdown; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Human Factors; Company Policy; Procedure
Found approximately 50 'Out of Date' [passenger] oxygen canisters in B and C zones on a B777-200 aircraft; date found on most canisters was [more than 15 years ago from date they were found].  This is the third time we have found this situation on the 777 fleet in recent past.  We have found these three aircraft have come out of Heavy C-Check; done in new [Maintenance] facility in a foreign country.  I do not believe that our air carrier has disclosed these discrepancies.  [Recommend] having C-Checks done in this country where the FAA can monitor and Department of Transportation (DOT) can drug test personnel working on aircraft.  Where people and our air carrier can be held accountable for the work accomplished. Removed and Replaced (R/R) oxygen canisters. [Lack of] adequate training.
A Lead Aircraft Maintenance Technician (AMT) reports finding 50 Passenger Oxygen Canisters that were 'Out of Date' on a company B777-200 aircraft. AMT noted the B777 was not the first aircraft in recent past that came out of a Heavy C-Check from a foreign maintenance facility with the same discrepancy.