A recent sighting at the Airbus Helicopters plant at Donauworth is this H135, with a large number of upgrades over the current production models.

Our analysis suggests the taller profile gives increased cabin headroom, and the side windows thus providing greater visibility for pilots – although there is no aft cabin window as found in the current models. The greater cabin height also means that the rear clam-shell doors are higher, improving access in roles such as air ambulance.

This development aircraft has five main rotor blades instead of the current four, which can be expected to mean smoother flight along the same lines that many pilots have noticed flying the five blade H145 D3 model compared to its D2 predecessor.

The “T” tail allows the the boom-mounted stabiliser to be removed. Early EC135 T1/P1 and T2/P2 model aircraft also had end plates on the stabiliser, while the later T3/P3 models did not.

There are significantly more composite materials being used in the fuselage, boom and tail, with earlier models only having composite blades and all the outer skin of the cabin, boom and tail being metal.

The overall side profile is certainly heading towards a similar shape to the H160, and that may in itself be intentional too.

Perhaps this is the “T4/P4” model? [Image provided to HeliHub.com by one of our contact network.]

and the older H135 T3 model as a comparison (this particular aircraft is the first production unit of the Helionix-equipped 135s)