Don’t Lift the Power Levers in Flight!

To the best of my knowledge, all King Air Pilot’s Operating Handbooks (POHs) have now been revised to include the following statement in the Limitations section:

Do not lift the power levers in flight. Lifting the power levers in flight, or moving the power levers in flight below the flight idle position, could result in a nose-down pitch and a descent rate leading to aircraft damage and injury to personnel.

That is rather straightforward, correct? Beta and Reverse are intended for use while on the ground, of course, not while flying. No pilot with a working brain would be so silly as to lift and pull back on the power levers while flying. Or would they?

Sadly, yes; some very misguided pilots do indeed intentionally select Beta while still flying. In almost every case this involves a model 200 with the standard, older, three-blade propellers. Those airplanes have a tendency to float in the flare for landing, especially if any excess airspeed exists, if the condition levers are not back at Low Idle,  and if the pilot overdoes the flare and holds the plane off of the runway for too long of a time. In this situation, coming slightly behind the power lever’s Idle gate causes the blade angle to go flatter, killing thrust, and causing the airplane to touchdown soon thereafter. Only in the 200, with its relatively long body and T-tail, does this crazy technique work. In the 90- and 100-series, the conventional placement of the horizontal stabilizer down on the fuselage puts the elevators in a position where the airflow over them is decreased as blade angle flattens, making it virtually impossible to hold the nose up for a satisfying touchdown. (The T-tailed F90 is definitely not a floater and this illegal technique is never needed, even though the elevators could hold the nose up!)

But what if the flare was misjudged, too high? What if the pilot pulled back a little too far into Beta? What if one propeller responded much differently than the other one? All of these “what ifs” can lead to expensive bent metal as the airplane lands too harshly and/or touches down significantly misaligned with the direction of travel, leading to excessive landing gear side-loads.

Here’s a sad, but true, story. One of the first 10 model 300s was damaged beyond economical repair during a factory training flight. The transitioning pilot reverted to this in-flight Beta selection technique out of the habit he’d developed while flying his company’s previous King Air 200. What he failed to realize – and what the factory instructor could not save in time – was that the 300, unlike the 200, has both a Ground and a Flight Low Pitch Stop (LPS) and the simple action of picking the power levers straight up – not even pulling them aft – makes the LPS flatten by about 12 degrees! Wham! The airplane basically fell out the sky and hit so hard that, among other damage, all eight propeller blade tips were bent back when the engine mounts sagging so much that the blades made ground contact! You never, ever, want to do this horrid procedure while landing a 300 or 350!

What if we are not landing though? What if there’s a fire in the cabin that we cannot extinguish, we are doing the correct emergency descent procedure, yet we want to get down even faster? Couldn’t we use some Beta now to get more drag, yet of course return to normal operation long before we hit mother earth? (Before continuing with the next paragraph, give yourself a little mental pop quiz. Would or would not this procedure help in obtaining a greater rate of descent?)

You’re wasting effort doing this and all you will possibly achieve is a badly mis-adjusted Low Pitch Stop setting.

I often state, “A pilot cannot force the propeller to reverse, he can only allow it to reverse.” Beta and Reverse are achieved simply because the power lever controls the position of the LPS. You can move the LPS, yes, but will the blade angle follow that moving LPS?

It all depends on whether power and airspeed are both sufficiently low that propeller speed has decreased, and fallen below the selected propeller governor’s value. Expressed in the more often-used terminology, Beta and Reverse can only happen when we are “off of the governor” or in an “under-speed condition.”

And, the easy-turning, free-turbine-driven propeller on a PT6 turns very easily, meaning that it takes very little airspeed or power to spin the propellers up to governing speed. Once the RPM becomes constant, the blade angle is now being controlled by the governor and is at some angle greater than the LPS angle. If we are no longer on the LPS, it makes no difference where it is.

The emergency descent procedure calls for using the landing gear extended speed limit as the proper airspeed. This varies from 156 knots to as high as about 180 knots, depending on the exact King Air model. Even with Idle power – also specified in the procedure – the propellers will still be solidly holding their maximum governing speed – and you’ll have the governor set for its maximum speed since the procedure also calls for prop levers being moved fully forward. In other words, you will be operating “on the governor,” not on the LPS, not in an underspeed condition, so moving the LPS back to flatter blade angles achieves absolutely nothing.

Two interesting notes: First, when I was a wet-behind-the-ears newbie instructor at the Beech factory and hadn’t learned enough to know better, one of the old-timers there regaled some of us with his “war story” about trying out maximum reverse in a King Air dive, and how the airplane pitched over almost straight down and was virtually uncontrollable until he moved the power levers back forward. Now I realize it was a story told to show how macho he was, but all it really proved was what a liar he was. Second, recall the placard on your King Air’s power quadrant, “Caution: Reverse only with engines running.” If you try to enter deep Beta or Reverse while sitting in the hangar or on the ramp with the engines not running, of course the propeller blades will be in the feathered position. That’s as far away from the LPS as they can get. If you now try to move the LPS, it cannot happen. Resistance on the lever’s cable will be felt and if some very strong and very dumb pilot continued to pull back, the cable could be stretched to the point that the whole LPS mechanism takes a real beating and gets badly out-of-whack.

Imagine standing outside of a closed, hinged door to a room. The door swings inward toward you. Grab the handle, pull, and the door opens. Now imagine that the door is already wide open, jutting out 90 degrees from the wall. Now grab the handle and pull. Nothing happens. The door is already at its widest open position and all you will feel is stiffness in your muscles as you pull, but the door does not move.

That’s a silly, but somewhat proper, analogy about what takes place if you select Beta and Reverse with the propellers not on the Low Pitch Stops … you’re trying to open a valve that is already open!

So to summarize, if we pick up the power levers and pull aft during an emergency descent, all we will get is resistance on the levers, possible LPS mis-rigging, and no extra drag.

Let me relate one more story from my Beechcraft factory training days, and this one isn’t a lie. In about 1974, I was giving transition training to a pilot who had been flying a King Air A90 that his company had replaced with a new C90. A part of our flight training syllabus was to give a real engine failure during a two-engine balked landing exercise. Needless to say, we had a rule to do all real engine shutdowns at or above 5,000 feet AGL. Typically, we would start a “make believe” landing pattern at 8,000 feet or so, and end up with gear down, full flaps, and landing speed all set no lower than 6,000 feet. As the instructor yelled, “Deer on the runway! Go around,” he would pull one condition lever to fuel cut-off. The whole intent of this exercise was to show that the procedure absolutely could not be accomplished without losing significant altitude; that full flaps and one engine, near the ground, was a commitment to land. If the pilot tried to hold altitude, speed would quickly be lost, getting us even further from VYSE and definitely close to VMCA.

This particular day, my transitioning student had been doing an excellent job, as would be expected with his previous A90 time. We had briefed this maneuver and he totally knew what to expect. I made the “Go Around” call and pulled the left condition lever back to the fuel cut-off position. He began executing the procedure perfectly: Power went to the proper ITT or Torque limit, the propeller levers were smoothly advanced full forward, the flaps came up, the gear came up, and all the while he managed to obtain and hold VYSE very nicely, as well as heading. This older C90 did not have the optional autofeather system, so now came the “Identity, Verify, and Feather” steps.

He said aloud, “Left foot is dead,” and pointed at the low reading on the left torque gauge. He then slowly and carefully pulled the left power lever back to Idle to verify that no sound or thrust change occurred. The landing gear warning horn was triggered by this action and he even reached for the button and silenced it! Only one thing remained, feathering. He brought his hand off of the silence button back to the power quadrant, grabbed the left power lever – the one he’d just brought to Idle – picked it up, and pulled it all the way back to Maximum Reverse!

If there’d been a video of my face, you’d be surprised how wide my eyes could open! And if there had been audio, you’d know that I am not averse to letting certain expletives leave my lips!

The airplane seemed to pivot around that left propeller as we turned about 90 degrees left and found ourselves in what seemed to be a straight-down pitch attitude … although I doubt it was much more than 20 degrees, if even that. I pulled power back on the right engine and pushed the left power lever forward over the Idle gate. Control was immediately regained so we eased out of the dive, added power on the right engine, leveled off, and got our heart out of our throats and back in to our chests.

In this situation, with slow airspeed and no power whatsoever, the left propeller had definitely reached an underspeed condition, resting solidly on its Low Pitch Stop. So when the LPS was moved to Reverse, the blades followed! Of course, without any fuel, we never added power as would normally happen when one leaves Beta and enters Reverse, but we certainly had a negative blade angle and all the extra drag that comes with it.

I looked over at my student and asked the obvious, “Why did you do that?!”

His answer was, and is, very interesting. He was feeling very embarrassed and stupid. His answer? “I did it because I saw the red and white stripes for Reverse and thought they were the red and white stripes for Feather.”

This early C90 – like more than half of all King Airs still flying today – did not have the Ground Fine power lever stop that came in later years. The only separation between Beta and Reverse is shown by the stripes being painted on
the power quadrant. There was certainly no intention on his part to lift the power levers in flight nor to pull them back into Reverse … but it certainly happened due to his error in selecting the correct lever for feathering.

As I keep saying, y’all be careful out there!