Agusta 109 de-ice
 

Hi

heard a rumor that old version of A109 had engine de-icing system ? is that true ? if yes why they resign of this nice feature in new models ?

Regards

I didnt fly the A109 except for a few flights in the left seat.

Anyway, it would’nt be [De-ice]. It would be [Anti Ice].
Getting ice and de-ice would mean that Ice sheds and go into the compressor. Which is Bad.

Anti Ice prevents ice to build up by continously being heated.

Most turbine engine in helicopters have some kind of anti-icing, either switch on/off or continoulsy workning, like the Makilas in the Pumas/Superpumas that use engine oil to always heat the intake.

Anti-ice is found on engines with a static support structure at the compressor inlet where there is a pressure drop and hence temperature drop. Shedding ice is a problem and also changing the shape of the inlet can lead to stall and/or flameout.

Early A109's had RR 250 engines which have a manual anti-ice. i.e. depending on the airframe install bleed air for anti-ice is used when OAT = -5C and moisture is visible. i.e fog, clouds, rain etc. Importantly you do not need to be in the fog, clouds or rain. It needs to be used if you can see any of the phenomena.

Not all engines have a manual anti-ice in smaller helicopters, PW 200 Series / Safran Arrius where the inlet is part of the oil tank and is therefore constantly heated, Safran Arriel where there is no static front support.

Later A109's have the PWC 200 Series engine so no anti-ice required.

As an aside there is a trap for the unwary on the AS350 if left out in the snow with no inlet cover. The snow / ice accumulates in the inlet plenum area but not enough to restrict flow until after starting the engine warms the plenum and a large slug of snow / ice then enters the compressor and "poof". Usually just after you get airborne - it has caught a few over the years. As the inlet is on top of the cowling and not visible it gets neglected.