A Texas law firm said it is finalizing a negligence and wrongful death lawsuit against a maintenance contractor in the crash of a UH-60 Black Hawk helicopter Aug. 22, 2007 in Iraq that killed all 14 soldiers aboard.

Ten of those soldiers were scouts with the 2nd Battalion, 35th Infantry "Cacti" out of Schofield Barracks. The four-member crew was based at Fort Lewis, Wash.

The night mission was to pick up two "small kill teams" totaling 20 soldiers who had been dropped off the night before for a mission in Multaka, near the northern Iraq city of Kirkuk.

Tom Harkness, a senior partner with the Texas law firm of Whitehurst, Harkness, Ozmun and Brees, said between 10 and 12 families of the dead soldiers from across the country are participating in the planned lawsuit against a unit of Massachusetts-based L-3 Communications.

"The mechanical work was done by a civilian contractor under contract with the Army, and the contractor was L-3 Contractors, which is a subdivision of L-3 Communications, which does a lot of Army work," Harkness said.

Harkness said the federal lawsuit will not seek a specific amount of damages when it is filed. That will be determined later.

The official Army investigation into the crash, a 224-page report known as an Article 15-6, doesn't provide a definitive answer as to what caused the helicopter to go down.

Harkness believes it was as simple as a small leftover spool of wire that caused the death of 14 soldiers and the loss of a $5 million helicopter.

Seconds into the flight, when the 18,000-pound chopper was at an altitude of about 150 feet and as the helicopter fought for higher air, Capt. Corry P. Tyler, the pilot in command, made his last radio call.

"1-2 is going down," he said.

Witnesses in accompanying helicopters reported between one and four rotations as the Black Hawk plummeted back to earth.

The Army investigation, obtained by The Advertiser through the Freedom of Information Act, and the most detailed account yet of the fatal crash, found that the soldiers suffered blunt force injuries in an impact of 150 Gs.

One G is the force of Earth's gravity. A fighter pilot coming out of a dive can experience up to nine Gs.

Lt. Gen. Raymond T. Odierno, the No. 2 U.S. general in Iraq, signed a Feb. 10 "memorandum for record" that said the Corpus Christi Army Depot inspected the downed Black Hawk airframe and discovered a gouged and cut tail rotor shaft.

An "unknown foreign object" in the tail rotor housing traveled aft and became lodged between the housing and the tail rotor drive shaft, causing gouging and cutting damage to the tail rotor, which then failed by sheering forces while under torque, Odierno's memo states.

The Corpus Christi Army Depot report concluded that the failure of the tail rotor drive shaft was the primary cause of the crash. Tail rotor control cable failure was secondary and occurred after the tail rotor problem.

"I find no pilot or crew error," Odierno said. "Origin and responsibility for the foreign object causing damage to the tail rotor drive shaft is not known."

No crews had reported enemy contact in the area, the investigating officer noted. The U.S. Senate earlier this month approved Odierno to replace Gen. David Petraeus as the top military commander in Iraq.

Loss of tail rotor control led to the fatal crash, Odierno said, adding, "The foreign object causing the damage was not found."

Harkness points to a damaged safety wire spool that was recovered at the wreck site. The wire is used like a cotter pin to prevent nuts from vibrating off bolts, and panels provide access inside the tail rotor housing, the attorney said.

"We feel that one of the mechanics that was performing that maintenance, while working up around the top of the helicopter ... he left a spool laying there, or dropped one, and it rolled back where he couldn't get it," Harkness said. "I tend to think he probably didn't know it was there, but he ended up leaving it in that housing."

The wire spool then made its way back in the housing, binding against the tail rotor drive shaft and ultimately causing its failure, Harkness believes.

The Corpus Christi Army Depot report does note that a damaged safety wire spool that was recovered in the wreckage and was sent to the lab.

The sentence referencing the find is a bit puzzling because it is seemingly garbled, noting, "analysis (of the spool) revealed traces aircraft aluminum material but insufficient and the suspected FOD (foreign object debris) could not be determined with certainty."

Harkness said a safety wire spool is not supposed to be in the helicopter during missions, and to him, that is another piece of circumstantial evidence.

"It is puzzling that the Army's report, and even the briefing to the families, said they didn't see anything that was related to maintenance (in the crash)," Harkness said, "especially since the only foreign object that was identified anywhere in the report was identified by Corpus Christi, and it was the wire spool that had been sent."

A spokeswoman for L-3 Communications said per corporate policy, the company doesn't comment on pending litigation.

A pilot who had flown the Black Hawk on the mission before the crash said in a statement in the investigation that "it was a sweet aircraft, so smooth that you could barely feel the rotors turning."

The pilot is unnamed in the information released to The Advertiser. For unexplained reasons, the Army redacted most of the names in the released materials.

The pilot also said, "L-3 runs a good safety program, and they are very thorough. They fall right in line with the Army program. I heard once L-3 ran out to an aircraft and had them shut down when they couldn't locate a tool in the hangar. I think they take safety very seriously."

Reach William Cole at wcole@honoluluadvertiser.com.