Bell is targeting maiden flight of its two new civil programmes – the 525 Relentless and the Short Light Single (SLS) – this year, but is still uncertain which will reach the milestone first.

“It’s going to be tight,” says Bell chief executive John Garrison, “they are both neck and neck. There’s a little internal competitive rivalry as to who flies first.”

Although launched in 2012, the Relentless is a more complex clean-sheet design whereas the SLS, unveiled last summer, uses existing transmission components.

Assembly of the first three 525 flight-test articles is underway at Bell’s Amarillo, Texas facility, says Garrison, with work on a total of five prototypes due to have commenced by year-end.

He says the manufacturer is “making great progress” with the design of the Turbomeca Arrius 2R-powered SLS and will unveil a full-size mock-up – and a new name – for the helicopter at the forthcoming HAI show in Anaheim, California.