Embraer Phenom 300
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew Diverted; General Maintenance Action
Aircraft
In cruise FL410 and noticed oxygen pressure was 1;250 PSI and had been 1;900 PSI an hour earlier during preflight. Contacted ATC and requested lower and they gave me FL330. During descent oxygen leak increased rapidly to where you could hear it coming from [caddy] that holds Captain's oxygen mask. [Advised ATC] and requested at least FL240 which was granted. Then asked for lower with next controller and got 10;000. At about this time requested and were granted direct [nearest airfield]. Approaching airport cancelled emergency and landed uneventfully.The metal coupling between the pilot's mask hose and the aircraft supply hose on the Phenom 300 needs to be beefed up. Half of the lip of the female fitting failed causing the leak. It is made of paper thin metal and subjected to stress when the mask is pulled out or put back in the well. Also it is a good idea to monitor oxygen pressure and cabin altitude when flying above 10;000 feet.
We were at cruise flight when we noticed the oxygen pressure at 1;200 PSI. The previous day it was at 1;900 PSI. With the oxygen mask out of the box where it was stowed I noticed cold air blowing in the box. I also noticed the fitting between the mask and the flow indicator being bent at a 20 degree angle. I went to straighten the fitting to make sure that it was connected properly and the fitting broke. Oxygen was escaping at a high rate through the parted connection. We turned the oxygen system off to save our oxygen in case we had other problems and needed the 900 PSI of O2 that we had left. We started a decent and ATC would only give us clearance to 33;000. We wanted to get down quickly and we [described the urgency] to get a lower altitude. We were cleared to 10;000. Once at 10;000 we cancelled the emergency and proceeded to [the nearest airfield].
An Embraer Phenom flight crew described a leak in the crew oxygen system that resulted in a descent and an uneventful diversion.