The family members and estates of two Atlanta police officers killed two years ago this week when a department helicopter they were flying crashed into power lines along Martin Luther King Jr. Drive have filed lawsuits against several companies involved in the manufacture and maintenance of the aircraft.

Officers Richard J. Halford, 48, and Shawn A. Smiley, 40, were helping search for a missing 9-year-old boy on the evening of Nov. 3, 2012, when the Hughes OH-6 helicopter hit the power lines near the intersection of Martin Luther King Jr. and Hamilton E. Holmes drives near I-20. The missing boy was later found safe, but Halford and Smiley died in the crash.

On Monday, attorneys for the estates of the two officers filed lawsuits in Fulton County Superior Court against the Hughes Aircraft Division of The Boeing Company, Honeywell International Inc., engine-maker Rolls-Royce Corp., Rotor Resources LLC, and Kenneth Paul Dudley, who overhauled the helicopter in 2005. There were various problems with the design and manufacture of the helicopter and its components, according to the suits.

The accident was investigated by the National Transportation Safety Board, which ruled last March that the probable cause of the incident was “the pilot’s failure to maintain sufficient altitude during maneuvering flight, which resulted in his failure to see and avoid a power pole and wires.”

In a report, the NTSB said: “Witnesses reported observing the helicopter at a very low altitude with the search light on maneuvering near the intersection of two city streets. Witness statements indicated that, as the helicopter neared the intersection, the landing skids collided with wires at the top of a 42-foot power pole. The helicopter then flipped over and crashed into the street.”

Atlanta police officials on Monday unveiled a memorial to Halford and Smiley at the crash site.