SN3, you quoted the whole sentence but it appears you didn't read the whole sentence. There is a specific condition attached to the idea I presented of light twins not being a 'true' multi-engine a/c. I even used apostrophes to show that I wasn't using the word 'true' in the literal sense.
There certainly *is* a concept of a requirement for continued flight 1 inop for multi engine aircraft - and that's judged by more than one criterion. FAR25 & equivalents are all required to demonstrate the ability to reject or continue & thereafter fly to a suitable landing place. Even some Part 23 a/c have a similar requirement imposed ie Commuter Category.
Further, additional regulations in many jurisdictions force the requirement for some asymmetric ability depending on the type of operation, Australian & JAA Authorities, for example, forbid the use of single engine piston aircraft for IFR pax charter - because of the perceived safety of having a second engine in case one fails. I should add that the relatively recent approval in Australia to allow Single Engine Turbines to be used for IFR pax charter was based on them being able to demonstrate an equivalent level of safety from an engine failure perspective. There are operational limitations that light piston twins needn't observe that SET must do for an equivalent level of safety precisely because of the requirement for a certain amount of asymmetric performance.
Even the general public's belief is that the second engine provides continued flight capability. Which, by the way, is rather well reinforced with companies pervasive use of phrases such as 'twin engine safety' and the like. Admittedly the general public can't be considered to be knowledgeable in the field but the underlying expectation is still relevent. If it wasn't then we wouldn't have to spend so much time hammering into brand new light twin pilots just what that extra engine means when a donk stops (not much in the take-off or landing configuration other than profoundly degraded handling qualities in most cases).
Part 23 (non-commuter) types aren't absolved from meeting some asymmetric climb performance. But in these cases the conditions attached aren't nearly as comprehensive & the required level of climb performance ranges from poor to non-existant, perhaps only enough to fly to a better crash site. Compared to the other multi categories' required asymmetric performance they are the 'nearly there's'.
frontlefthamster, surely you're not suggesting that the a/c is not controllable at Vyse? What about at Vxse? I must disagree with your assertion that a speed margin above blue line is what provides the means to recognise & handle a failure. To say so would mean that any max performance take-off will automatically result in a Vmc departure following a failure. 'Blue line' as depicted on the ASI isn't even a fixed quantity except for a constrained set of conditions. It sounds like you're confusing Vmc (a controllability issue and itself variable from the certification figure) with Vyse (a performance issue) whilst ignoring Vxse at the same time. In that respect you're quite correct: You should not become airborne below Vmc because of the high probability of an uncontrolled crash.
Yaw, secondary roll, control inputs to stabilise the aircraft & gauge indications are the usual indications of failure - and they all occur at speeds above & below Vyse. To avoid flying at a best performance speed that is above Vmc because you believe that the speed buffer will give a better failure indication is not wise. You would look pretty foolish if an engine stops with obstacles still above you having squandered what limited energy you had prior to the failure.
Any competent & current pilot should be capaple of controlling a failure at blue line and should not need a buffer above blue line to control the aircraft. Not to be able to do so reflects poorly on the pilot's training &/or currency.
With respect to Asymmetric Commital Height, I'm familiar with the term as used in Europe. I don't think 500' is too high for it. Under adverse WAT conditions there can be a significant height loss until established in the climb. Don't know about you but even though I might be able to have the asymmetric beastie cleaned & climbing from 300' without hitting the ground , I strongly prefer not to put myself at ~100-200' (or less if things are *really unfavourable) going around on one engine with bugger all climb performance. I'd rather land beside/behind/ahead of the idiot that taxied onto the runway in front of an aircraft with a declared emergency.
And by the way, I suppose it is theoretical and my 25 years experience, over 20 of which has been flying a broad range of Part 23 twins including instructing & examining, counts for little. Even so, it's still the case that sound theory engenders good practice.
Last edited by Tinstaafl; 27th Jul 2008 at 00:27.