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Can I Backup My King Air? - Tom Clements, King Air Academy


Can I Backup My King Air? - Tom Clements, King Air Academy

Most all of us have been there. We have maneuvered into a particularly tight space on the ramp – either due to the lineman’s directions or to our own sense of necessity – and now find the need to extradite ourselves from this predicament. Problem is, there is not enough space to roll forward and make the turn. We need to back up. Can we?

“Of course not, you idiot! The POH says that you cannot be in Reverse below 40 knots. Since you’re starting from a stopped condition, it’s not an option!”

Not so fast, Mr. By-the-book! Let’s say that, instead of a mistake on a commercial ramp, we’re in a war zone and an incoming mortar just cratered our expected taxi route. If we don’t get to the runway right away, we’ll be trapped for the night and unlikely to survive to the dawn. Yet if we back up, we can get to the runway. What now?! Or, more realistically, if we wait for the FBO’s tug, we’ll lose our departure time slot reservation and not make it to that meeting where the possibility of a multi-million dollar contract awaits. Again, what now?!

The easy and correct answer is to shut down, find a tug no matter how long it takes, and push the airplane back to a spot from which only positive thrust will be required for maneuvering. And folks, if there is a tug available within a reasonable period of time, this is the only correct answer about how to handle the situation. In fact, if there is a tow bar available and enough people-power to push and pull, it is still the best approach.

Unfortunately, today neither option exists, no tug, no tow bar, no abundance of helpers. Now what?

The only realistic option is to use propeller reverse to back up your King Air. Should this ever be done? No! Can it be done? Yes. As Dirty Harry said in the movie, “Are you feeling lucky, punk?” If luck is on your side, you’ll do this and the engines, propellers, and airframe will suffer no harm whatsoever. If luck is not being a lady tonight, you may end up with a propeller nick, a dent in the nose caused by a propeller-flung pebble, and, possibly, even first stage compressor FOD. Are you feeling lucky, punk?

Let’s stack the deck in our favor so that luck favors us. First, what is the condition of the ramp? Only if it is paved and in relatively good condition will backing up likely yield no harm. Second, what’s behind us? It’s pointless to execute a flawless backup maneuver that protects our engines and propellers well, yet we ram our tail feathers into that Gulfstream that snuck in behind us!

The third item that stacks the deck in our favor is to extend the engine ice vanes, to turn on Engine Anti-Ice for the pitot-cowl-equipped airplanes. Whether this really adds much “stacked deck” in our favor is debatable. Why? Because the ice vane system is designed to be effective when airflow off the propeller is normal, moving aft. When we are in reverse and the propeller is pushing air forward, the ice vane system is no longer working in its optimal manner. However, if a piece of FOD gets sucked up past the cowling lip and the sucking action of the compressor tries to ingest it, the extension of the ice vane provides some additional level of protection.

The next item that will be beneficial here is to move both condition levers to High Idle before selecting Reverse. This gives us more baseline engine power and makes the changing thrust caused by blade angle changes more immediate. The N1 spool up factor is nearly eliminated so that blade angle changes take center stage.

Now, with ice vanes extended and the condition levers at High Idle, pick up both power levers and move them through Beta, up over Ground Fine (if applicable), and now gently release the brakes as you start feeling the negative thrust. Ah, there it is! We are starting to move backward and we find it is surprisingly easy to control the negative thrust by making minor forward and aft power lever movements. If we need to turn, the nose wheel steering is effective and works the same as when going forward. Namely, push left rudder pedal to make the airplane go left.

Here comes perhaps the most important point of this entire article: While rolling backward, do not use brakes to stop! Instead, move the power levers forward to stop the reverse travel and only then apply brakes!

If we stomp on the brakes while going in reverse, there is a strong tendency for the airplane to pivot about the main tires with the nose coming up as the tail comes down. More than one King Air has suffered extensive damage when it rocked onto its tail, sending the ventral fin or aft body strakes into the fuselage! This expensive mistake is easily avoided, however, by merely using positive propeller thrust to stop backward travel, not brakes.

Am I really advocating backing up your King Air using reverse thrust! No! Go back and re-read my comments about using a tug or people-power instead. Folks, this is a last-ditch emergency procedure with an unavoidable level of some risk. However, being realistic, if you fly a King Air long enough there will come a time or two that this maneuver is the solution to a lengthy delay or perhaps a canceled flight. Using the procedures discussed here – a relatively clean ramp, ice vanes extended, High Idle, never using brakes while rolling backward – may stack the deck favorably enough for you that no damage is incurred.

Author: Tom Clements, King Air Academy

Banner image: by @flyingwithdebby