An interesting situation in Tandem Rotor helicopters is when one head enters translational lift and the other does not....which frequently happens if a takeoff at max possible weight (MPW) is attempted. MPW being where you exhale to lighten the load while creeping off as smoothly you can for any roughness of control touch results in a settling back to earth.
As the forward head enters ETL....the tendency is for the nose to climb as the forward head is producing more lift than the aft head....an application of forward cyclic cures the pitch up problem but also decreases lift in the aft head...if your rate of acceleration is insufficent to get both heads flying in ETL....major problem.
A very common techique for acheiving MPW performance was to use Yaw pedals to swing the aft head into clean air and combine the sideways rotation of the airframe and the cleaner air to bring the aft head into ETL at the same time as the forward head. Timing was of the essence in that maneuver.
It is great fun to find yourself behind the power/altitude/speed/experience/idea curve with the Mr down from 230 rpm to 190 rpm, gennies dropped off line, and SAS kicked out due to loss of electrics....while holding the thrust level up under your armpit and trying to think up a sound explanation that will satisfy the Accident Review Board.
MPW by the way is the real ACL (Average combat load) for the aircraft as found in reality vice the SOP's.
We asked a lot of the old girls and their held together pretty well considering the abuse they got.