ATA 35

During an operational check of an aircraft oxygen system, it was determined that a passenger oxygen drop down mask would not let oxygen flow. The fault was in the connection between the smaller tube and the larger tube attached to the barbed fitting on the oxygen drop down box. There is supposed to be clearance for oxygen to flow, in this case the smaller line was squeezed shut and would not allow oxygen to flow to the mask. The part number in question is a 174080-31 Rev “K”. The, Batch was LC0526K. This lot had been shipped around July of 2005. A thorough inspection of the masks that are installed in your aircraft is recommended. This inspection should include a functional test of the mask as well as the aircraft system.

Please refer to the IAI AMM 35-00-00 Oxygen system adjustment and test paragraph 1, Steps (1) thru (36).