This thread is meant to compliment the one on the use of Carb Heat.
In flying training engine problems are usually presented as binary. Engine runs engine doesn't run. However the engine malfunctions that the average PPL is much more likely to actually encounter is a rough running engine and/or a loss of some engine power. What to do about this hardly ever seems to be covered in flight training.
I recently helped redo the emergency checklist for a local flight school and I addressed this issue in the non memory recall section. The intent is a "check" for the pilot use if he/she encounters an engine problem. It goes as follows
Engine Roughness/Reduction in Engine Power
-Carb heat.........................................Full On for at least 30 sec
-Engine gauges...................................Check
(Note if severe carb ice exists engine will initially run very rough until ice has cleared)
If problem persists
-Carb heat........................................Cold
-Mixture ...........................................Full rich then lean to max RPM
If problem persists
- Mags............................................Select right and left mag individually
(Note if engine roughness is more pronounced on one mag select the other mag or both, whichever gives smoothest operation)
----------------Land at nearest suitable airport------------------------
If problem persists
- Fuel selector.................................Left for 2 mins
If problem persists............................Right for 2 mins
---------------Land at nearest suitable airport-------------------------
In addition to to this I have emphasized the importance monitoring the engine instruments in flight. Instructors now periodically and without warning cover the oil temp/press gauges and make sure the students know where the needle is actually pointing. (In the green is not a good enough answer
).
Internal mechanical failures resulting in a total engine failure are the least likely cause of an engine failure but they do happen. The good news is there will almost always be some warning. Any internal misalignment or failure will almost always result in metal rubbing. This will cause a rapid rise in oil temperature with the oil temp gauge pegging at its maximum value. A dramatic drop in oil pressure will quickly follow. Any engine showing these signs should be presumed to be in danger of imminent total failure and appropriate actions to land ASAP should be taken. The only caveat is an open circuit in the oil temp wiring will cause the oil temp needle to peg at the highest temp. However in this case the oil pressure will be normal so it is likely just the gauge. However a landing at the nearest suitable airport would be prudent