vancouv:
Gliding is not something that would normally enter the equation as the aeroplane in question has two engines, unlike a PA28. Because of this, there should be no need to consider gliding as the statistical probability of losing both engines is tiny. In short, lose an engine on a PA28 and you have to glide - lose an engine on a twin and you SHOULD still be able to fly on the remaining engine.
As a result, following an engine failure, the intention would be to return to the airfield for a single engine approach. The approach would normally be flown with a lesser flap setting than for two engines, and a slightly higher approach speed to compensate (typically 5-10kts faster). The lesser flap setting means less drag, requiring less power (and therefore creating less asymmetry) but also gives less lift, hence the higher approach speed. The higher speed also gives better control authority, meaning (in theory) better control response.
They would aim to fly the approach at a 3 degree descent angle - the same as for an ILS approach or visual approach. A 3 degree descent will bring you down at a rate of 320' per nautical mile and so if they were 2500' above ground level, they would take an approximate 8nm approach (plus about 2nm for getting settled in final approach track and configuring for approach).
However, when manoeuvring with an engine out, care must be taken to avoid letting the speed get too low as there is less thrust available to recover. If speed is allowed to get too low then the rudder/fin lose control authority and due to the asymmetric thrust caused by one engine, it will become increasingly difficult to maintain directional control. In extreme cases, the aeroplane will yaw and then roll, ultimately entering a spiral dive or stall.
Turning increases drag and therefore will tend to cause IAS to reduce. If IAS reduces far enough, directional control will be compromised and, if the speed drops far enough, drag will increase dramatically as the aeroplane finds itself on the "wrong side of the drag curve".
Some twin engined aeroplanes are a little short on power following an engine failure and may struggle to maintain airspeed when turning - especially if they are heavy (as this Citation was). In such cases, it may be very difficult to avoid a significant speed loss in a sustained turn - such as a base turn onto final approach.
My suspicion, for what it's worth, is that the most likely cause of the crash was that, following a loss of power, the speed dropped too low whilst manoeuvring and directional control was compromised. However, we may never know for sure.
Last edited by moggiee; 4th May 2008 at 23:06.