There was a prgram that went on a Psion that did M&B and Perf for the AS355. It came from an engineer at McAlpine in the UK I believe. The biggest problem might be finding an old Psion to run it on. I understand that the person concerned lost interest in maintaining it and puttng it onto later devices.
I am always on the look out for such a programme that will run on a modern PDA, for the types that I fly. It is not too difficult to develop an Excel spreadsheet for a hele, but it is not really practical to cart a notebook around with you. What is needed is something that will run on a PDA IMHO. One probem is that the market for such things is not huge, so it is likely t be a labour of love rather than truly commercial.