There are Parameters that Carburetter heat should Meet. It seems to Me, the whole thing is getting a bit Lax. Engine failures due to Icing will continue to Happen. Injection reduces the Likelihood significantly. Evidence of Icing disappears often so the fault goes Undetermined. Proper technique is APLY FULL Heat BEFORE reducing Power for descent and don't have Prolonged Power OFF descents. It can Barrell face Piston rings too. Nev