B777-200
Maintenance Airframe
Training / Qualification; Communication Breakdown; Confusion
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance
Chart Or Publication; Human Factors; Procedure; Aircraft
While working an Engineering Repair Authorization EC/EA and AD 2012-11-09; Step 2-B1 appears to have the mechanic inspect the existing cable; install the mask and insert [Release] Cable pin into the striker pin of the cylinder if no damage was found. There was a misunderstanding by the [maintenance] crew of Step 2 of AD 2012-11-09; since the mechanic had to install a new cable; which is not addressed in AD 2012-11-09. As a result; the Cable assembly and oxygen masks were incorrectly installed on a B777-200 Aircraft during reactivation of the Oxygen System.Additional reference should include an Illustrated Parts Catalog (IPC) 35-21-01-40b (item C) for a better understanding of [Release] Cable routing. Also add a [maintenance] step to install any missing cable to [passenger O2] box; including hardware; into the Engineering Kit for AD 2012-11-09 and better training.
An Aircraft Maintenance Technician (AMT) recommends an additional reference be added to Airworthiness Directive (AD) 2012-11-09 to include Illustrated Parts Catalog (IPC) 35-21-01-40b; (item C). The IPC would provide a better understanding of the Passenger O2 mask box release cable routing. Misunderstanding of Step 2 of the AD resulted in an incorrect installation of the release cable and O2 masks on a B777-200 aircraft.