Date: 201907
Aircraft: B777-200
Operator: Air Carrier
Flight phase: Parked
Aircraft component: Oxygen System/General
Reporter organization: Air Carrier
Reporter function: Technician
Human factors: Confusion
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
Result: General None Reported / Taken
Contributing factors: Procedure; Manuals; MEL
Primary problem: Manuals

Narrative: This [Safety Awareness Program] is going to generate more than ONE problem!Was assigned Aircraft X LP 38XXXXX [Oxygen System] unit robbed for Aircraft Y. After getting possible need part from [Company] went to aircraft and found that the Entire [Oxygen System] unit was missing. Part that was AOG'd (Aircraft On Ground) in for aircraft was 80XXXX-XX. But the part was Oxygen O2 Generator MEL 25-XXXX-X-XXXX = 80XXXX-XX. But needed case also. Since the Deferring station on Aircraft Y removed unit. Per MEL card 35XXX # 35XXY replace or service or remove.NOTE: Affected Unit may remain in place within storage location if unit is placarded.After finding NO IPC (Illustrated Parts Catalog) reference for the Installed [Oxygen System] Single-PAK's went looking in the configuration drawings. 25XXXXXXXX Rev. B. I did find a reference for these units Item XX = 80XXXX-XX = MEL 25-XXXX-X-XXXX = O2 Generator not a complete unit. Then went to the CMM (Component Maintenance Manual) Vendor [Oxygen System] SYSTEMS (need to search for the [Oxygen System] series 80XXXX) then select 35-XX-XX. Near the end section of the CMM is the Vendor IPC. Item XXX = generator which is = 80XXXX-XY = MEL 25-XXXX-X-XXXY. Which is NOT ALLOCATED TO STATIONS. Then item XXY Generator = 80XXXX-XZ = MEL 99-XXXX-X-XXXX which is allocated to stations Then item -X 80XXXX-XA [Oxygen System] Single-Pak. This has a MEL 25-XXXX-X-XXXZ. But has it as NON HAZMAT (Hazardous Materials) and a description of Case; Portable Breathing Unit without Generator. But when you order this MEL you get a Cannot ship from [Company] people due to the generator is shipped with case.Aircraft Y LP 37XXXXX. [Oxygen System] emergency seal broken.[Maintenance] looked at unit found that it was activated (used) so they used MEL 35XXY. they removed unit and placarded storage location. Released aircraft. 8 days later aircraft at ZZZ somebody wants LP cleared. According to the other installed units it needs a 80XXXX-XX unit.But this is only a generator NOT a [Oxygen System] unit. But this part is available in ZZZ1. So they AOG it. After this they go looking for a aircraft that they can rob from. They find Aircraft X they generate a LP 38XXXXX to show that they robbed the Unit for Aircraft Y. Now this is a MEL swap to another Aircraft. So should the date of discovery from Aircraft Y be moved to Aircraft X?Vendor CMM 35-XX-XX [Oxygen System] System. IPC Fig 1 Item -X 80XXXX-XA is a single-pak [Oxygen System] unit. But [Company 2] has it as a single-pak [Oxygen System] unit without generator. But there is one within the carry case! Needs a new [Company 2] description and NEW MEL#IPC Fig 1 item -XY 80XXXX-XB is a single-Pak [Oxygen System] unit. Has NO MEL. IPC Fig 1 item -XZ 80XXXX-XX is a single-Pak [Oxygen System] unit. But when you get this part is a O2 Generator without the carry case! IPC fig 1 item -XA 80XXXX-XC is a single-pak [Oxygen System] unit has No MEL. IPC fig 1 item -XB 80XXXX-XD is a single-pak [Oxygen System] unit has No MEL. IPC fig 1 item -XC 80XXXX-XA is a single-pak [Oxygen System] unit has NO MEL.Rework MEL card 35XXX. Spec Notes: add to Note C . [Oxygen System] Single-Pak unit(s) not properly serviced are replaced; serviced; or removed at the next available maintenance station where parts are available. Operations PLACARD: Each [Oxygen System] unit contains One Generator Pack. Each Generator Pack Supplies 20 Minutes of Oxygen at 2 LPM for TWO ONE users. Question (insert MEL 35065; 35XXX; 35XXZ; 35XXA) If a single pack with ONE generator supplies 20 minutes at 2 LPM for two users with only ONE mask. Then; A [Oxygen System] DUO-PAK with TWO generators should then supply 40 minutes at 2 LPM for two users?




Synopsis: Maintenance Technician reported confusing documentation in regards to Supplemental Oxygen Units.