Originally Posted by
Robbiee
Hmm, I've got around 350 hours of solo experience in these conditions in an R22 at night over San Francisco. I'd say the cause of this one wasn't really that he didn't use carb heat, but that the reason he didn't even unlatch the carb heat assist, was due to being distracted by it being a photo flight.
Flying solo is easy, but once there's someone next to you, its sooooo easy to get distracted and forget things.
The way I'm reading that, the carb heat knob was indeed unlocked, but found in the full down (off) position. So it can't be determined with 100% certainty where exactly it was when the aircraft was flying, as it moves up and down in response to the collective. For example, if the pilot raised the collective to max pitch before impact, that would also lower the carburetor heat knob to off, (almost) regardless of where it was before. Of course I can't second guess the conclusion that carb ice was the most likely cause here.
What is a little surprising to me is that there is, after 40+ years, still no bulletproof solution to this carb ice problem that affects especially the R22. How is it possible that the carb air temperature gauge STILL doesnt accurately show what the temperature is inside the critical area of the carb, as it does on the R44. The procedure, paraphrased is still "go by the gauge, but depending on power just add carb heat anyway, because this critical gauge doesn't read correctly at half the time, and if it all goes wrong you got about a second to get the pole down or you are dead. Good luck". Carb ice is far more common than loss of engine oil pressure for example, and it will shut your engine down at least as fast but with fewer warning signs. There's a red light for the oil pressure and a redundant gauge. How is there not also a big yellow warning light that turns on when the cat gauge is in the yellow arc. Or an automatic electric - or engine oil based heater in addition to the mechanical. All this stuff exists and has been in use in other carburetor engines for half a century. And that's before you consider fuel injection.