1.   Boeing said the cabin lost pressure when an air-duct clamp disconnected and led to the failure of a check valve.

2.   A check valve, which is supposed to stop the air from flowing in the wrong direction, then failed, he said.

3.   A check valve operates something like a pet door.

4.   Most check valves are held in place with a rubber sleeve and hose clamps.

5.   Next install the check valve on the riser.

6.   The check valve has a flap which opens and closes as fuel is removed.

7.   The check valve in the Canadian currency area is capital and labor mobility.

8.   The check valve is necessary because it prevents pumped water from falling back into the liner when the pump shuts off.

9.   The inlet check valves also had significant damage.

10.   The part, known as a vacuum system manifold check valve, is an important element in several instruments of the plane, she said.