Have you ever seen this procedure described? I hope your answer is “Yes,” since it is the title of a procedure presented in the Pilot’s Operating Handbook (POH).
Quiz time: In what POH section will you find it? Section 3, Emergency Procedure? Section 3A, Abnormal Procedures? Or Section 4, Normal Procedures?
I will wager that less than half of our readers answered correctly, with “Section 4, Normal Procedures.” But indeed that’s where it is found, right after the procedure titled “Simulating One-Engine-Inoperative (Zero Thrust).” Since multi-engine training is a normal procedure that can be done, and often is done, in King Airs this makes both of these procedures quite normal.
Here is the entire written procedure found in the B200 model’s POH:
PRACTICE DEMONSTRATION OF VMCA
VMCA demonstration may be required for multi-engine pilot certification. The following procedure shall be used at a safe altitude of at least 5,000 feet above ground in clear air only.
WARNING
IN-FLIGHT ENGINE CUTS BELOW VSSE SPEED
OF 104 KNOTS ARE PROHIBITED.
- Landing Gear UP
- Flaps UP
- Airspeed ABOVE 104 KNOTS (VSSE)
- Prop Levers HIGH RPM
- Power Lever (simulated inoperative engine) IDLE
- Power Lever (other engine) MAXIMUM ALLOWABLE
- Airspeed – Reduce approximately 1 knot per second until either VMCA or stall warning is obtained.
NOTE
Use rudder to maintain directional control (heading) and aileron to maintain 5° bank towards the operative engine (lateral attitude). At the first sign of either VMCA or stall warning (which may be evidenced by: inability to maintain heading or lateral attitude, aerodynamic stall buffet, or stall warning horn sound) immediately initiate recovery: reduce power to idle on the operative engine and immediately lower the nose to regain VSSE.
I believe that this procedure is an important one for all newcomers to the King Air to experience and I included it in most of my initial flight training sessions. Simulators are wonderful training devices but they are stronger in some areas than others. This is one of those procedures that most simulators do not replicate well.
In 100% of the cases in which I have used this procedure in training, the demonstration was terminated when the indication of an impending stall was found. Never once was there an actual “inability to maintain heading or lateral attitude.” Well, let me clarify that … actually, there were numerous times when the heading started to drift toward the inoperative engine’s side and the student felt that he/she had actually found VMCA and therefore terminated the maneuver. However, he/she had not pushed the rudder pedal as far as it would go … usually, not by a long shot! When we repeated the demonstration with proper control usage, the impending stall indications were the reason the demonstration was terminated.
When I was a neophyte factory King Air instructor back in 1972, I recall one of the test pilots commenting to me that VMCA testing was one of the most stressful maneuvers that experimental test pilots had to perform. “Wow! It gets really scary, huh?” was my response. His answer was, “Yes, but the only scare is that we will run out of fuel before we get back to Beech Field!”
I found that the only way the loss of heading or lateral attitude control would happen before the stall was when the airplane was exceedingly light in weight. Thus, minimum fuel was always on board during this testing. Prior to this, I had believed that all of the speed numbers published were based on maximum gross weight … as you probably think also. But, no, VMCA is usually only found – at least in Beech twins – at light weight.
VSSE is the abbreviation for Intentional One-Engine-Inoperative Speed. It is defined as: “A speed above both VMCA and stall speed, selected to provide a margin of lateral and directional control when one engine is suddenly rendered inoperative. Intentional failing of one engine below this speed is not recommended.”
This “V speed” was not defined until sometime in the 1970s. It came in response to the distressing number of multi-engine training accidents that were forthcoming from VMCA demonstrations. As instructors, it makes sense to never give a student an engine failure while too close to loss of control speed!
If I were the one to have written Beech’s “Practice Demonstration of VMCA” procedure, I would have made two changes … for the better, I hope. First, in the “Note” portion, reducing power to idle is the correct response when VMCA is encountered. (And as I have presented, that never happens during this demonstration!) But for a stall recovery all we need to do is reduce the angle of attack by lowering the nose. A lot of unnecessary and undesirable loss of altitude will be experienced if power is retarded during the stall recovery, especially all the way to idle. I would suggest that leaving power alone on the good engine and simply lowering the nose to increase airspeed would be the better, safer procedure.
Second, again in the “Note” portion of the procedure, I would add “or above” after “lower the nose to regain VSSE.” Wouldn’t we almost always want more than just this very low speed as the demonstration is terminated? Of course. Additionally, I will mention that I usually start the demonstration at an airspeed of about 120 KIAS, near blue line. That complies with the “Above 104 knots (VSSE)” yet provides more time to ease into the maneuver.
You will notice that use of trim is not mentioned in the procedure. The comment about reducing airspeed by “approximately 1 knot per second” can only be accomplished by raising the nose gradually and climbing since maximum allowable power remains on the “good” engine. It is common and correct to use pitch trim to compensate for the changing elevator force as speed is reduced.
But what about rudder trim? Since it is not addressed, one could argue that you can “Do whatever you want.” On the other hand, since encountering true VMCA during normal flying almost always would involve an unexpected engine loss of power with little reaction time, I request that no rudder trim input be made. That allows the student to experience as great of a rudder force as he/she will ever be required to give. Hard? Sure! Manageable? Quite easily!
If your particular King Air model is equipped with the rudder boost system, it will be operative during the VMCA demonstration. In the case of the 300-series, in which the system varies the rudder force applied based on the difference in engine power, you will be receiving a bit less help during this demonstration than when an engine has actually flamed out. Why? Because the lower power engine is at zero thrust, still running, not totally dead. Keep in mind, as I have tried to emphasize in previous articles, that rudder boost helps by applying some force on the appropriate rudder cable but it, alone, is not nearly enough at VMCA. Use your legs!
Speaking of zero thrust: I believe the torque/RPM combination that Beech specifies in the procedures for their different models are accurate. However, in my experience, they tend not to be as consistent as a method I developed and have used for a very long time. It appears that the torque indication – at these very low values – is not as accurate nor as reproducible as the other method.
Try this: Bring the power lever to idle and pull the propeller lever back to, but not into, the feather detent. This will set the propeller governor at its lowest governing speed. In the 200-series, for example, you’ll have close to 1,600 RPM. Now adjust the condition lever to get between 60 and 65% N1 or Ng. I bet that torque will be quite close to Beech’s Zero Thrust value but pay it no mind.
Some King Air models base VMCA on a feathered, not a windmilling, propeller. This applies to all of the 300-series, as well as to most four-blade-equipped members of the 200-series. This changes the VMCA demonstration procedure by setting zero thrust on the lower-powered engine instead of idle.
Here are a few closing thoughts. As I stated, the real airplane is usually the only accurate way to experience the true handling characteristics of your King Air. With proper safeguards – primarily, enough altitude – these maneuvers can be done very safely. If you have not yet experienced an idle-power, full break, stall in your King Air, you should! These are very gentle airplanes in which a stick shaker and/or stick pusher are not required. They stall very much like a big Bonanza. How about pumping the landing gear down by hand? Ever done it in the actual airplane? It bears only passing similarity to the simulator, doesn’t it? I firmly believe that the more comfortable we become in our actual airplane the more likely it is that we will react in a correct and timely fashion when facing an abnormality or emergency.