Flysundone
If you have only one engine---that`s the critical one!
If you have two c/l engines (Cessna337/o-2),then I think maybe the rear one is the critical one,as the performance on that engine alone is better than on the front one alone(less drag from prop -wash over fuselage( but I await correction as I`ve not flown that type).
If you are in a twin or multi-engined a/c (piston or turbo-prop) then the critical engine will be the one that has prop blades that( viewed from the rear) have their down-going blades on the side nearest the aircraft fuselage.
The reason it is "critical" is that in the event of failure,the engine(s) on the other wing have their thrust-lines to the right of the engine centre-lines ,and therefore apply a greater yawing moment "with" the dead engine,which can limit the a/c`s control ,both on the ground and in the air. The reason the thrust is greater is due to the relative airflow angle on the prop blade when inclined,produces greater thrust,and this will be also offset outboard,producing greater yawing moment,which must /will show as a greater rudder deflection,or foot-force to overcome. For certification purposes limit loads are between 150-180 lbs depending on the a/c`s Certification Authority/ age. On some a/c ,failure of a critical engine may require a reduction of power on the live engine to maintain control-Canberra
PR-9?
Referring to my earlier post,the DH Hornet had handed engines,(both turning "inwards"), to prevent the critical problems of the Mosquito, as also a Naval a/c doesn`t want to be going sideways on a deck t/o; so, it didn`t have a "critical"-per se; the P-38 Lightning prototype also had a similar configuration,but during flight testing it was found that there was a lot of fuselage buffeting due to the direction of prop rotation,so the engines were swopped around,and it worked okay.So,one could say the a/c has two "critical" engines,but it does fly well on either one and does not have a significant handling problem...Must have another glass of "vino collapso " after all that!!
