Turbine-stupid

When PA-46 piston drivers asks me about the operational costs of a turbine PA-46, I tell them the cost associated with a turbine on a comparative-trip-basis are very similar to operating a piston.  But, I always include one caveat…turbines are cheap to operate as long as the pilot doesn’t do stupid things.  Stupid in a piston is relatively cheap compared to stupid in a turbine.  I know, I know…there’s no such thing as “cheap” in aviation, but even in aviation terms, turbine-stupid is downright expensive.  So, how do you fly your turbine “cheaply”?  The answer is avoid turbine-stupid.  Here’s the list of things NOT to do in a Turbine PA-46:

  • Don’t do a battery start with less than 23v present on the battery(s):  The big killer of a turbine is a hot-start, and the best way to hot-start a turbine is to have low battery voltage at start.  The Fuel Controller dumps an exact flow of fuel into the combustion chamber when the Condition Lever is advanced at start.  If there’s plenty of airflow to meet that fuel, a cool start results.  If the engine is starving for air when the fuel is introduced, a hot-start is imminent.  The best way to ensure good airflow is to ensure the starter is turning as fast as possible. The best way to ensure a fast starter is a good battery. Check battery voltage before every start and don’t EVER start it without good voltage.  Either get a “cart-start” or put the batteries on chargers.  Don’t believe me? Check your trend monitoring data (you do have trend monitoring in your PA46T, right?) and compare the start temps with the battery voltage.  I assure you there will a direct correlation to a weak battery voltage and high engine temps during starts.
  • Don’t turn on the ignition switch out of sequence:  Let’s say you are in a hurry and try to start your PA-46 Turbine without the checklist.  You hit the starter button, wait until the Ng rises appropriately, and advance the condition lever.  But, “light-off” doesn’t occur in a normal time frame.  You look around the cockpit and notice the ignition switch is “OFF”.  If you turn on the ignition switch late, you will get to see the most expensive fireworks display ever.  Flames may shoot out of the exhaust and the ITT will rise uncontrollably.  If you are lucky, only a Hot Section Inspection will be required.  If you let lots of fuel pool in the engine before lighting the fire, you might send shrapnel out of your cowling.  If you ever forget to turn on the ignition switch prior to advancing the condition lever, you must shut off the condition lever immediately and abort the start.  On the next start sequence, make sure to get a “Cart-start” and motor the starter for at least 30 seconds prior to advancing the condition lever.  This will provide the best opportunity for you to evaporate as much of the additional fuel in the combustion chamber prior to giving it more fuel on the start sequence.  Plus, the start-cart will give you additional air, resulting in a cooler start.
  • Never operate the condition lever “in between”:  The condition lever is a “fully ON” or “fully OFF”” lever.  Place it fully forward if you want the engine to operate, and place it fully aft if you don’t.  There is no “in between” place for the condition lever.  Read this story for a description of what could happen.
  • Never operate the MOR lever during start: The MOR (Manual OverRide) must be “OFF” for start in either a Jetprop or a Meridian.  If it is in any other position, then excess fuel could be dumped into the combustion chamber during the start sequence, initiating a hot start.  To create a Hot Start, all that is needed is for the fuel-to-air ratio to be improperly rich during start.  So, limited air intake (low battery voltage, tailwinds, etc.), or excess fuel (MOR Lever engaged) are the enemies.  There’s lots of reasons to NEVER play with the MOR Lever, but the best is that it’s a great way to fry your engine.  It is designed as a way to control your engine in the event that normal control is not possible, and you should check it’s operation before the the first flight of the day (follow the checklist).  But, never have a “let’s see what happens” approach to playing with the MOR Lever.  Certainly, never have it in any other position but “OFF” for the engine start.
  • Never perform a Soft Field Takeoff: There is simply no reason to ever do a soft-field take off in a PA46T.  Here’s why…the torque (yaw) applied by the engine cannot be overcome at slow speeds without the nose wheel having lots of friction on the ground.  The excessive yaw created by the powerful turbine can only be overcome by (one of) two forces: 1.) friction of the nose wheel to the surface of the ground, and 2.) rudder forces once the rudder gains enough airspeed.  If a Soft-Field take off is performed (holding the nose off the ground and “riding a wheelie” until lift-off is attempted), the nose of the PA-46T will yaw left and full right rudder will not be able to overcome the pressure.  The airplane will yaw uncontrollably left, the airplane will exit the runway, and an accident will occur.  NEVER allow the nose wheel of a PA46T to leave the ground until the airspeed is 70KIAS or higher.  Then, there will be enough air moving over the rudder to allow the rudder to counter the yaw produced by the engine.  As a related side-note…an icy runway is particularly dangerous in a PA46T for the same reason…the nose wheel does not have enough friction with the surface to counter the yawing forces and the nose will go left prior to the airplane becoming airborne.  The PA46 is really not a great soft-field airplane anyway. Avoiding grass in a PA46  (except in the most controlled of environments) is probably a good idea.
  • Never “power out” of a stall/spin:  It seems counterintuitive, as most people think that power will help in a stall/spin scenario.  But, power is the enemy in a stall/spin due to the yawing forces created by the power, especially in a turbine since more power is available.  Here’s a guarantee…if you try to power out of a spin, the spin will only tighten and become more flat.  There’s been many stall/spin accidents in the PA-46 community lately, and I’m concerned that power was a culprit in the scenario.  To recover from a stall/spin, follow the PARE method:
    • Power: Must be at idle
    • Aileron: Neutralize
    • Rudder: Push opposite the direction of turn
    • Elevator: Push forward to break the stall

If the power is left ON in a PA46T during a stall/spin, the airplane will not recover from a and everyone onboard will die in a terrible crash.  I don’t mean to be melodramatic, but the facts have proven themselves many times in the last few years.  A stall/spin scenario is not recoverable with power in a PA-46T with power ON.  Don’t be the test-pilot that tries to prove me wrong.

There’s lot’s of other ways to spend money in aviation, so I hope you are able to avoid these examples of Turbine-stupid.

 

About Joe Casey

ATP, CFI, CFII, MEI, CFI-G Commercial Pilot - SE, ME, Rotorcraft, Glider US Army AH-64 Pilot and UH-60 Instructor Pilot and Instrument Flight Examiner
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