I was asking info on the Bizjets forum but it seems to have died. What would YOU have to say about whether a light twin takeoff, including Baron, Chieftan and Kingair, should be planned on the basis of an engine failure? Is it necessary? A good idea? Would you say it should be done for the turbine but the piston airplanes are exempt? If it costs money due to reducing weight or not using a small airfield, would it be acceptable to you or your company (Part 91 survey flights no passengers carried)?
What has cost to do with it? Every takeoff, regardless of whether it's a B747 or a J-3 cub, should be planned not with the possibility of losing an engine during the takeoff, but planning for it. Not just in a light twin. Not just in a Part 25 airplane with detailed second segment performance. Even a single engine airplane should always be flown with this in mind. It's not just a good idea; there's no other way. Know what the airplane will do and where it will go, and plan accordingly.
Should you be calculating performance in a light twin? Of course.
You don't know any pilots that do, you say? I surely do. I want to know what the airplane can do on both engines, one engine, how far it will take to get off the ground, clear an obstacle, stop, what the climb rate will be, what my options are after the fact, what lies off the end of the runway, where emergency fields are, including off field forced landing sites. If you're not doing this, you're taking a very big gamble and operating on substandard level. It's just not acceptable.
Should you be limiting your choice of fields and payloads to account for aircraft performance with and without equipment failure? Of course.
Without question.