Originally Posted by
ShyTorque
Yes, but when starting the first engine it's generator isn't immediately online - the first high load is taken by the battery. As soon as the first engine's generator comes on line it will try to replenish the battery. If the second engine is then set to crank, the first generator may get overloaded because it's replenishing the battery and supplying a load to crank the engine.
The earlier Squirrels reputedly had a delicate quill drive to their starter/gennies. The generator switch wasn't selected on until after engine start was complete because in starter mode the quill drive is driving the engine. In generator mode the quill drive has a reverse load, i.e. the engine is driving the generator. The critical part was the sudden reverse load/torsion, caused by driving to being driven.
Normally the first engine started generator is brought online after the start sequence is complete, and there is a maximum current allowable before the second engine can be started (if using the first generator, rather than external power) stated in the RFM, e.g. "AMPS 1 Indicator ............check at or below 150 amps". I think this is what you were actually saying, but is not what Ascend described.
The second scenario is also accurate and is one reason why the GEN Switches are checked as being OFF in the prestart checks. Obviously all of the above only relevant for those types with a combined starter/genny - big aircraft typically use MGB driven AC Gennies and may also use pneumatic starters.