Bell Helicopter has confirmed a three-month delay to the certification of its developmental 505 Jet Ranger X, with the milestone moving from late 2015 to the first quarter of 2016.

Initial handover to an undisclosed customer will now follow shortly after, says Bell chief executive John Garrison, conceding that the manufacturer's "aggressive timeline" had "slightly slipped".

Nonetheless Garrison remains upbeat about the programme, with its three prototype aircraft having accumulated over 400 flight hours since the type's maiden sortie in November last year.

So far Bell has amassed over 340 orders for the Turbomeca Arrius 2R-powered light single and had a mock-up on display on its Helitech stand.

Work on the initial production aircraft has begun at the airframer's newly opened final assembly line in Lafayette, Louisiana as Bell attempts to negotiate what Garrison describes as a "pretty significant ramp-up" on the programme.

"The challenge there is to ensure that the supply chain is ready to go. Frankly we are not at all worried to ramp up final assembly," he says.

Turbomeca has already delivered the first serial Arrius 2R turboshaft and is aiming for engine certification by year-end, says Bruno Even, chief executive of the French powerplant manufacturer. A further serial engine will be handed over this year, he adds.

Meanwhile, development of the heavier 525 Relentless is "progressing nicely", says Garrison. First flight took place on 1 July and a second prototype of the GE Aviation CT7-powered super medium should join the fleet by year-end with Bell's ambition to have a third flying by early March next year.

US certification of the 9.1t rotorcraft is scheduled for early in the second quarter of 2017, several years behind Bell's European rivals whose super-medium helicopters are already in service.

However, Garrison argues that delay means the Relentless will arrive on the market as the offshore oil and gas segment begins to recover from its current slump, kicking off a wave of helicopter replacment.

"We want a robust market - although it hurts us at the moment on the 412, it will help us on the 525."