Leonardo Helicopters will in the coming weeks wrap-up a flight-test campaign to validate improvements to the AW101 that will offer pilots more power and control.
Tests have been under way since 2021, including a hot and high campaign performed in the USA last summer. Since then, the trials have transferred to Italy, where the rotorcraft has conducted sorties from Cuneo and Asiago in the country’s mountainous north.
Deliveries of AW101s with the enhanced performance package are already under way to an undisclosed customer, but the manufacturer is confident other operators will also sign up.
Tests in the USA last year were carried out using a Royal Norwegian Air Force-operated aircraft.
Key to the upgrade is an increase in the main gearbox (MGB) torque rating at take-off to 117%, a five percentage point rise from the previous 112% figure.
This lifts available take-off power to 5,830shp (4,350kW) – or 1,943shp for each of the AW101’s three GE Aviation CT7-8E engines – up from a total of 5,580shp previously, or 1,860shp per engine.
Performance in hot and high conditions is improved, alongside the helicopter’s one engine inoperative (OEI) capability.
In the most extreme case, transient take-off power for 6s in an OEI condition, the MGB’s torque rating will now sit at 142%, yielding 4,720shp from the two remaining engines.
Pilots will also benefit from changes to the engine-control software that reduce the point at which safety systems would normally kick-in.
Rotor speed can now be allowed to decay to 95%, down from 98% previously, before the so-called ‘blow away’ feature is triggered, which automatically applies emergency power.
Kristian Daines, AW101 performance improvement programme manager at Leonardo Helicopters UK, says the changes to the engine-management system “allows more controllability before the safety mechanisms kick in, which gives you the ability to fly in tighter spaces and take-off from more difficult airfields”.
The blow away feature also risks over-torqueing the MGB, requiring unscheduled overhaul of the component.
“From an operator point of view, not only are we giving them more power, we are giving them better handling qualities, and preventing unintended maintenance,” says Simon Tutcher, chief engineer for the AW101/EH101 at Leonardo Helicopters UK.
“It’s something that will have a large effect on the AW101 in terms of its capability and also its support.”
Overall, the enhancement “is the most significant change we have made to the AW101 since we introduced the CT7-8E [engine],” says Tutcher.
Tests are due to wrap up in November and should culminate in certification for the enhancement being granted by Italy’s military airworthiness authority.
Changes are required to the engine management software and to the flightdeck displays to accommodate the upgrade. While in theory it could be applied to any AW101 with the correct gearbox and the latest CT7-8E engines, Tutcher says the airframer has no plan “to actively roll it out to other existing customers”.
“From a baseline point of view moving forward, this is the default for the AW101 now.”
Because they are equipped with Safran RTM322 engines, the enhancement cannot be applied to the UK Royal Navy’s fleet of AW101 Merlins as part of a planned life-extension programme.
Although the upgrade is being fielded by an initial operator, “we are working with a second customer to develop it further – that includes HMI [human machine interface] assessments and improvements to the whole operating system to make it as good as it can be,” says Tutcher.