This page is dedicated to the differences involved in flying single engine turbine airplanes. The information presented is broad-stroke application to this specific variety of airplane. Each airplane will have its own specifics. In short, know what’s best for your type of airplane.
Single Engine Flameouts (SFOs)
Modern-day turbine engines are very reliable. That does not mean they never fail though. Any pilot who flies should be prepared for the worst. If your turbine engine dies on you there are several procedures you want to be very proficient at so you can either get the engine running again (if that is a possible choice) or land safely, preferably on a runway. If the engine does not die but is having serious problems or failure is expected (e.g. loss of oil pressure), then you likely want to fly a Precautionary Emergency Landing (PEL). Either way, the pattern is the same.
Here is an example of an emergency landing pattern. This is pretty typical for SE turbines. Knowing High Key and Low Key is crucial. One difference of note with the graphic below is that I recommend you aim for 1/3 down the runway. This way if your glide is off and comes up a little short you still have pavement underneath you. If you do this correctly then you can still land on the first 1/3 of the runway. If you are in a turboprop with a dead or malfunctioning engine then remember you may not have reverse thrust to slow you down. Also consider when to put gear down. I usually wait until abeam the aimpoint on the runway on downwind for gear.
I was amazed to find out that not all single engine turbine aircraft owners are taught a SFO/PEL pattern. If you have never been taught this then I suggest you find someone who can teach you and get out there and learn it well. Being able to fly a pattern like this, and being able to intercept some portion of the pattern if your altitude is too low to fly the entire pattern, is a must!
Rollback
Turbines can experience a condition called ‘rollback’. This is when a failure causes the Ng (gas generator speed) to rollback to a low-idle (ish) speed. The engine will be running, but not make any power. On several single engine turboprops, there will be a backup method of controlling the engine. A quick and easy analysis is: The engine is showing a low Ng and an idle-ish ITT , no power is being made, and moving the Power Control Lever (PCL) does nothing.
At this point the solution is to use the Manual Override Lever. It may have a different name. I have seen MOR, MAN OVRD, and Emergency Fuel Control as different labels. What these emergency controls do on an engine (at least on a PT6) is bypass the Fuel Control Unit (FCU) fuel metering and manually move a fuel flow valve, providing unmetered to the engine. Extreme caution must be used, as moving the control too quickly can cause over temps (too high ITT), over torques, or other problems. Follow engine manufacturer guidelines.
Common causes of rollback are: P3 air leaks, PY air leak, and FCU speeder spring failure. This may not be an all-inclusive list of malfunctions.
It is important to get competent training on how to use a MOR control, and a pilot has to remember that he/she has one! The best way to remember is to include its use as part of initial and recurrent training. I have heard that at least one single-engine turboprop manufacturer does not do this training. I strongly disagree with that philosophy. With understanding of how the system works, the MOR control can be used easily and safely.
More info to come…
Mike Kloch Aviation Consulting 