Under the US' FARs, there are light twins that are not required to have *any* asymmetric climb performance, only that their performance 'be determined'. That could be determined to be -ve ie downhill at xx ft/min, even with everything done to maximise performance.
Countries that require +ve climb performance will often impose a climb weight limit.
Last edited by Tinstaafl; 16th August 2012 at 06:52.