That't typical behaviour for carburettor icing, which obviously depends on weather. you can have carb icing at 15C on low throttle settings.
this lua-script pops up values is you have carb icing, or you can assign the command FlyWithLua/BN2P/Toggle_CarbIceDisplay to display it constantly.
if PLANE_ICAO == "BN2P" then
CarbIce = dataref_table("sim/flightmodel/engine/ENGN_crbice")
create_command("FlyWithLua/BN2P/Toggle_CarbIceDisplay", "Toggles the CarbIceDisplay", "CI_displaytoggle()", "", "")
showCID = 0
function CI_displaytoggle()
if showCID == 0 then showCID = 1
else showCID = 0
end
end
function show_CarbIce()
if showCID == 1 or (CarbIce[0] + CarbIce[1]) > 0.02 then
draw_string(50, 70, "L Carb Ice: " .. math.floor(CarbIce[0]*1000)/1000)
draw_string(50, 50, "R Carb Ice: " .. math.floor(CarbIce[1]*1000)/1000)
end
end
do_every_draw("show_CarbIce()")
end
Carb icing is most pronounced in high humidity air with low throttle settings.