From the US Coast Guard Boating Safety Site:

Alerts

CO2 PFD Inflator Failure




PFD INFLATION FAILURE DUE TO FALSE-POSITIVE SERVICE INDICATORS AND
INCORRECT CO2 CYLINDER INSTALLATION


The U.S. Coast Guard has been made aware of a potential problem when
installing CO2 cylinders that have bayonet tips in inflatable personal
flotation devices (PFDs or life jackets). If a cylinder is not properly
installed, the PFD will not inflate with CO2. The problem may affect
several thousand PFDs, but the Coast Guard is only aware of one incident to
date.


Some Mustang, Protexion, and Stearns/SOSpenders PFDs using
Halkey-Roberts' inflators can indicate a green "Ready" status when the CO2
cylinder is not properly installed. This false positive green indication
occurs when the cylinder-bayonet assembly is inserted in the inflator, not
turned, and the cylinder is not ejected.


Cylinders with bayonet tips are designed to be pushed in and turned
1/8th turn clockwise to a full stop to secure the cylinder. When the
cylinder is not turned to secure it in place, the PFD will not inflate with
CO2. The PFD may still be inflated orally. If the CO2 cylinder is not
turned, the mechanism is supposed to eject it. In some production units a
false positive green indication can be achieved by simply pushing the
cylinder into the mechanism without turning it 1/8th turn to a full stop.
According to the consumer report, a user was led to believe the
cylinder-bayonet was properly engaged without turning it due to the firm
seating of the cylinder-bayonet, which also prevented the cylinder-bayonet
from ejecting as designed.


Consumers should check the model number of the PFD (located on the
manufacturer's label) to see if your PFD is affected.

The models numbers are listed at the following website::


http://www.uscgboating.org/alerts/alertsview.aspx?id=50