Extracting and stowing the crew oxygen mask

**Effectivity: Challenger 300, Challenger 350 and Challenger 3500 aircraft**

ATA: 35

By: Yvan Tremblay—Technical Services

This article provides instructions on how to properly extract and stow the crew oxygen mask

P/N: MC20-019 into its crew seat-mounted stowage cup P/N: MXP160.

Please refer to the two videos demonstrating the procedure provided with this article:

One video demonstrating a Correct procedure.
One video demonstrating an Incorrect procedure.

It is important to carefully follow the stowage instructions to avoid damaging the mask due to inadequate manipulation and to ensure that the inflatable harness properly inflates upon mask extraction.

Correct procedure

Incorrect procedure

Stowage instructions

Fold the inflatable harness inside the mask shell cavity. The inflatable harness shall be folded from left to right and then from top to bottom. Do not unmethodically stuff the inflatable harness inside the mask shell cavity, as this might prevent the inflatable harness from properly inflating upon mask extraction.

CAUTION

TAKE CARE NOT TO BREAK THE REGULATOR TABS.

2. Insert the mask so that the nose piece goes in the stowage cup first. Once the face piece is engaged in the stowage cup, rotate the mask downwards to align the regulator tabs with the stowage cup slots.

CAUTION

TO AVOID DAMAGING THE OXYGEN MASK, BE CAREFUL NOT TO PUSH ON THE OXYGEN SUPPLY HOSE.

3. The mask should be in an upright position with the regulator tabs aligned with the stowage cup slots. With your hand, squeeze the oxygen mask regulator and the stowage cup until the inflation red tab is fully seated within the stowage cup.

Make sure the inflatable harness is not trapped between the mask regulator and the lower part of the stowage cup, as this will prevent the mask regulator from locking (clicking home). The inflatable harness should be behind the mask shell cavity.