Ang
…I have always been taught to run up one engine at a time. Is there a technical reason for running them up together or am I missing something….
It’s an ‘Airmanship’ thing so disregard the responses from the cowboys. Your instructor probably taught you the correct method. In doing so he has ‘risk managed’ a whole heap of ‘bad karma’ that has manifested itself through years of multi-engine operations. Here are some that I see:
Since engines are started independently then on a cold day the second engine may not have reached operating temperature in the run-up bay.
Running-up both engines at once doubles the risk of ‘brake-creep’ and leads to wiping out the expensive Learjet ahead of you – or the fuel truck. This normally happens when ‘head-down’ in the cockpit fumbling with switches and levers and looking at gauges!
The guy taxiing past in the tail-dragger is more likely to ‘ground-loop’ with double your propwash at run-up power!
Why not check your company operations manual, the AFM or ask the CFI if you are renting his twin. Procedures different from those published just make more loopholes for the insurance companies and the courts!
Discount all the convenient excuses for double run-ups put forth by the cowboys – after all, the time saving is just a few seconds but you might carry the consequences for life.