Boeing is evaluating damage to its aircraft sections after they fell into a river when a Montana Rail Link train derailed 18 miles east of Superior, Montana, US.

This incident may affect the company’s tight aerospace supply chain, which relies on just-in-time deliveries of components to meet record demand for aircraft.

On 3 July, 19 cars in the 90-car train derailed in the incident, with three cars containing aircraft parts ending up in the Clark Fork River.

The incident sent three aircraft fuselages into a steep embankment into the river, with the three remaining aircraft sections also derailed but staying on land.

"Once we determine the extent of damage we will assess what, if any, impact there will be to production."

The train was transporting six 737 fuselages, fuselage panels and a lower lobe for the 777, and a leading-edge flight surface for the 747.

It was headed from Spirit Aerosystems in Wichita to the Boeing final assembly plant in Renton.

Work is currenting taking place to hoist up the three Boeing 737 fuselages, the large, central portions of planes that hold passengers, and it may take until 8 July to remove the units.

A Boeing spokesman said: "Once we determine the extent of damage we will assess what, if any, impact there will be to production."

Boeing said that it was not yet known if the accident might affect production of planes.

Montana Rail Link spokeswoman Lynda Frost said that cause of the derailment was not yet known, but added that speed was not considered to be an issue.

There is a 35mph speed limit on that section of the track, which is curvy as it tracks the Clark Fork, she said.