I agree. A very insightfull post by chimbu.
Originally Posted by Big Kev
What I don't understand that well is why we go mixture through then range and throttle through the range - surely you'd want the mixture to be full rich right? - so why go in and out with the mixture lever? How can anything get blocked in a fuel control unit?
In addition to the fact that an engine needs fuel and air to run, it also needs to be at a combustible ratio. If you have a fuel
restriction, (the engine is still receiving fuel but at a reduced rate) retarding the throttle might reduce the amount of air being drawn into the engine to a point where the ratio between the fuel and air becomes combustible once again. This might restore a very limited amount of power, which is obviously better than nothing. Similarly if the air intake has been restricted, (assuming alternate air is not available or has not worked) reducing the mixture might bring the fuel/air ratio back into a combustible range, therefore restoring a limited amount of power.
FMOST is a simple mnemonic that instructors use which covers most bases in most piston aircraft in a short amount of time.The best defence in any abnormal situation is to know and understand your particular aircraft - especially the fuel system.