The Chicago Tribune reports that a flight originating from Fort Lauderdale airport was forced to make an emergency landing after the aircraft suffered a mid-air mechanical failure. The airplane had left the Florida airport at approximately 7:45 on Sunday morning. The engine failed shortly into the flight and the plane was forced to return to Fort Lauderdale airport to make an emergency landing.
According to Federal Aviation Administration spokeswoman Kathleen Bergen, this was 'contained' engine failure. A contained engine failure is one in which engine components such as fan blades break or come apart in the engine but are then either ejected out of the back of the engine, or stay within the engine itself. Airplane engines are designed to facilitate this sort of contained engine failure which usually do not pose an immediate flight risk, but will require a precautionary landing such as this one.
When an airplane suffers an engine failure in which the debris is not contained or ejected out the back of the engine, it is known as an 'uncontained' engine failure. In the more serious scenario of an uncontained engine failure, components from the engine are shot out of the engine in other directions. This can pose a serious risk of injury to passengers and or to the integrity of the airplane.
In regard to the engine failure yesterday, a spokesman for Delta airlines says that the Delta flight 1846 was taking off when an indicator light alerted the captain of possible damage to one of the engines. Pieces of the engine were later found near the airport by local sheriff's deputies. Fortunately, no injuries were reported in this emergency landing.
Source: Chicago Tribune "Engine failure forces Delta flight to make emergency landing at Fla. airport after takeoff" February 20, 2011