Carby Ice

[Waddles]

Gents.For what it"s worth, the use of permanent carby heat is not recommended without a carby air inlet temp gauge. Under certain conditions where you"re operating outside the icing range, the use of carby heat will bring the carby air temp into the icing range. eg. Using chooks chart, assume a temp of 0* and a relative humidity of 40%. This is outside the carby ice range. Now add some heat to raise the carby air temp to say 15*. Now you"re in the serious icing range!In certified FW a/c without a carby air temp temp gauge, it is normal to leave the heat off until the engine starts to play up. Then apply full heat. The engine will continue to sag as the ice melts off and the resultant water is ingested. The hotter carby air will also contribute to loss of performance. After a short time, turn carby heat off and the engine should be restored if the ice has cleared and this was the reason for the loss of performance. In low powered, prolonged descents, carby heat is applied once the throttle is reduced. Remember to turn it off if a missed approach is carried out. That"s how it was 45 years ago anyway.Waddles.

[Brian]

Just a reminder of the conditions required for carby ice - always an eye opener.Regards........Chook.It is an eye opener, many people think once the temp has warmed up a bit, there"s no chance of ice. Some engines [ aircraft] make ice faster than a industrial ice maker

[Brian]

Whilst talking carby ice, read an article the other day about an engine failure on takeoff [fixed wing] and its worth reporting cause I was taught it was extremely rare to near impossible with WOT to get ice and this is probably fairly correct as I"m guessing....big guess that the pilot on command did not apply carby heat during his run up checks as ice would most likely have been detected then and the pilot should / would do a carby heat check again on lining up. I say this cause the pilot never applied carby heat when the engine failed. All checklists will say to apply carby heat...specailly when the noise stops as the ice can melt very quickly and an engine re start can be made sucessfully .Sounds like the pilot panicked as well cause he never established best glide speed and actually flew it into the ground below stall speed without actually stalling it. Course, it landed heavily & wrecked a good aircraft.The article also mentioned an accident last year where carby ice was attributed to the cause of the accident { FW ] so the moral of the story is if you fly an aircraft with a manual carby heat, learn how to use it !!