One of the safety checks we conduct on every gas grill we test determines whether the burners go out when we drop the lid from a height of about 6 inches above the closed position. Two OutdoorChef Roma 570 MX2 units failed the lid-drop test; their two burners repeatedly extinguished when on the low setting.

The propane gas continued to flow, resulting in a potentially dangerous situation. That failure makes the grill (shown) Not Acceptable, which means it poses a safety risk to users. The risk from the situation is low, but no grill should have this flaw. We advise against buying the Roma 570 MX2 Roma at this time.

Our technicians perform the test, similar to a standard industry one, with the burners on low and high. The burners on both Romas went out almost every time when on low, and gas continued to flow. They did not fail the test when on high. All other rated grills passed the lid-drop test on both settings.

Our technicians did follow-up tests with the burners on low: They dropped the lid, which extinguished the burners; let the gas build up for two 5-minute and two 10-minute periods; then reignited the burners from about 6 feet away using a sturdy rod. They reported no problems on three occasions; after one of the 10-minute periods, when they relit the grill with the lid closed, they heard a short burst of gas igniting.

We notified the Consumer Product Safety Commission of the product's safety risk and asked the agency to investigate.

We also contacted the manufacturer, whose president didn't dispute our findings but told us that the model had been certified by the Canadian Standards Association to meet applicable U.S. safety standards. (The Roma is made in China by Swiss company OutdoorChef International and distributed in the U.S. by Advance Outdoor Concepts.)

Don't drop the lid on your grill when you're cooking, especially if you own a Roma. If the burners extinguish, turn off the gas, and with the lid open, let the gas dissipate. Reignite the grill according to the manufacturer's instructions.

Essential information: If you're in the market for a new gas grill, check out our buyer's guide to outdoor cookers and ratings (available to subscribers) and watch our video buying guide.