June 7, 2018
The pilot performed an engine run-up at 3,500 rpm along the entire length of the runway and then turned around for takeoff in the opposite direction. After rotation, the engine lost partial power. The airplane descended and struck a tree at the end of the runway before coming to rest in grass near the runway end.
Postaccident examination of the engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The atmospheric conditions at the time of the accident were conducive to the accumulation of serious carburetor icing at glide power and icing at glide and cruise power. The engine was not equipped with a carburetor heat system.
I don’t know what percentage of Rotax 912 engines have carburetor heat installed but it’s got to be extremely small to virtually nonexistent.
Carburetor icing does seem to be rarer in these engines. My 1998-2024 homebuilt accident database shows just three cases (including this one) involving carburetor icing Rotax 912-powered homebuilts. That’s out of a total of 462 accidents of homebuilts with Rotax 912s.
Probable cause on ERA12LA131 states, “A partial loss of engine power due to carburetor icing. Contributing to the accident was the lack of an installed manufacturer-recommended carburetor heat system.”
Probable cause on ERA16LA247: “The pilot’s failure to maintain airplane control after a total loss of engine power due to carburetor icing, which accumulated because the carburetor heat was not functioning.”
Curiously, all three aircraft were amphibians. Seastar, Aventura, and Searey.
I dug out another database I have for Special Light Sport Airplanes, and found another four cases of carburetor icing on Rotax 912-powered airplanes:
ERA14LA219
ERA09FA005
CEN13LA398
ERA16LA148
This database cover SLSA accidents from 2008 through 2021; 418 total accidents, of which 284 had Rotax 912s.
Now, carburetor icing is impossible to prove after the accident. It melts. The NTSB investigator look at the charts showing the probability of icing, and, if it shows a serious potential for icing and they find no other cause, they may attribute it to carb ice.
It should be noted that, in all four of these accidents, the Probable Cause referenced the pilots failure to apply carburetor heat…so the four accident aircraft had it.
Rotax 912’s don’t have carb heat in Vans RV12’s as there’s a coolant radiator, oil cooler and exhaust system keeping the tightly cowled interior volume toasty warm.
Searey’s carbs are hanging out in the breeze.