After The Prop Stops

One of the oldest jokes in aviation holds that the big fan is there to cool the cockpit: Whenever it stops unexpectedly, the pilot starts to sweat. Every aviator who’s had that experience can probably confirm a significant uptick in pulse and respiration. In the best case, that’s accompanied by a corresponding intensification of focus, rapid execution of the memory steps of the emergency procedures checklist and efficient assessment of available alternatives. In the worst...well, those pilots aren’t available for interviews, but tapes of their radio transmissions can make for uncomfortable listening.

Another old adage suggests that the first step in addressing an in-flight anomaly is to wind your watch. This helps restrain the kind of impulsive, ill-considered action that might aggravate the problem. An engine stoppage, though, is one of the rare exceptions, an emergency in which seconds can really count. A sluggish or inappropriate response can quickly make a bad situation much worse. While the subsequent course of action depends on the circumstances, the first step is always the same: Lower the nose (or the collective if you’re flying a helicopter). How much and how fast depends, like everything else, on airspeed, attitude and altitude.

Chances are that the first and simplest mnemonic you learned during primary training was for an engine failure: “ABC.” It broke down, as you may recall, to:

To this we would add a “D”: Declare an emergency if you’re already talking to ATC; this will jump-start search-and-rescue efforts and narrow the search radius. If you’re not, though, don’t waste time trying to find a frequency unless you’ve got plenty of time— meaning altitude—to spare.

If you’re not sure of your airplane’s best-glide speed (which wasn’t routinely published prior to the 1978 POH standardization), shoot for a couple of knots slower than V_Y (V_YSE if you’re flying a twin). In cruise flight or on approach, you’re probably going faster than that already; unless you’re within gliding distance of a runway, bleed off the extra by holding altitude as long as possible. The pitch adjustment needed to stabilize airspeed afterward will be fairly gentle.

If you lose power climbing out, however, the necessary reaction is anything but. A firm shove is needed to preserve airspeed during the transition from climb to descent. Minimizing altitude loss begins with avoiding a stall, which will chew up a couple of hundred feet even if you recover before hitting the ground. If you don’t, of course, it’s game over. In fact, the majority of fatalities in takeoff accidents (of all kinds, including power losses) result from unrecovered stalls.

The default runway at the Frederick (Maryland) Municipal Airport is 23, which boasts 5219 x 100 feet of well-maintained asphalt and an ILS approach. Less enticing are the choices available to a pilot who suffers a low-altitude engine failure on departure: either a limestone quarry or a propane-tank distributorship. Fortunately, better options come into range if the engine keeps running another minute or two.

Conventional wisdom warns against attempting more than a 30-degree heading change after a low-altitude loss of thrust. This rule is pretty sound. Steep bank angles shed more altitude faster, increase stall speed as you fight the instinct to pull on the yoke, and make it harder to level the wings before touchdown. We’d caution against trying to make the “impossible turn” back to the airport from anything less than pattern altitude unless you’ve specifically practiced this maneuver and know your airplane very, very well. (AOPA’s Air Safety Institute has in-cockpit footage from a Mooney that successfully pulled this off. After watching it half a dozen times, we still expect him to end up in the trees.) Instead, look for the largest clear area you’re sure you can reach. If there aren’t any, try for obstructions that will dissipate some of your energy by breaking (like trees) over things that won’t (like boulders).

In cruise flight in daytime VMC, you should at least have a couple of minutes to pick out a landing site (which doesn’t mean there’ll be a good one). Prospects won’t be nearly as good in IMC and/or at night, something to take into account while planning your route. Except in remote areas, IFR pilots can at least request vectors from ATC; if possible, also read them your GPS coordinates to define the search area as specifically as possible. Any vacuum-operated gyroscopic instruments will quickly spin down, leaving you to manage your descent and turns partial-panel while hoping to spot salvation after you break out. At night, well … One school of thought suggests turning on the landing light. If you don’t like what it reveals, turn it off again.

Clyde Cessna famously said, “If your engine stops for any reason, you are due to tumble and that’s all there is to it!” Maybe not. Reportable accidents due to physical failures of engines, fuel systems, or propellers have been relatively rare in recent years, around one per 200,000 flight hours. But forced landings don’t always qualify as accidents (see “Aviation Accident Data For Skeptics” in Aviation Safety’s July 2018 issue), and not all engine failures end off-airport. If we optimistically assume that each case in the NTSB database is matched by a successful save, the resulting rate—around one per 100,000 hours— means that most pilots’ flying careers will never include that experience. (So if you’ve survived more than one, count yourself truly blessed.)

Of course, fractured crankshafts and clogged tank vents aren’t the only things that shut down powerplants. For many years, fuel mismanagement— chiefly dry tanks, plus the odd dollop of water or Jet-A top-off—produced more NTSB reports than components breaking in flight. Carburetor icing remains a common accident cause. Procedural errors—the wrong mixture or boost pump setting, or even forgetting to switch the mags back to “both”—can rob the engine of power or strangle it entirely. More than one pilot has learned that there’s just enough gas in the lines to get off the ground with the fuel selector turned off.

If you were lucky enough to make it to a runway, try to make as normal a landing as possible. Put it on the numbers if you can, but err on the side of reaching the pavement rather than coming up short. If you have to land on a road, do your best to find a gap in traffic. Landing with the flow is almost always better than facing it head-on. Keep in mind that drivers won’t be aware you’re there until you magically appear in front of them, and will have no idea what to do. If you can coast onto a shoulder, do.

Otherwise, the goals are always the same. The first priority is to reach some unobstructed area if possible. A close second is to touch down, wings level, at the lowest speed that preserves positive aircraft control. Remember to open the door or canopy first, then extend the latch to prevent it from jamming shut. If there’s time, shut off fuel and electricity. Don’t hesitate to sacrifice more peripheral parts—like wings and landing gear—to avoid or reduce impacts to the cabin. The machine’s already an insurance claim; don’t risk injury to save the underwriter money.

Retractable pilots must also decide whether to extend the gear (if still feasible). It should absolutely be left up for a water ditching to reduce the chance of flipping on touchdown. The same argument may apply to very rough terrain, forest, or a plowed field if there’s not room to land parallel to the furrows. If your open space is very tight, a belly landing will shorten the ground run considerably. If you’ve found a relatively smooth area of decent size, though, put ’em down. The airplane may not be a complete write-off yet.

We haven’t mentioned ballistic parachutes because a majority of the fleet doesn’t have them—but if you do, making it your first option rather than your last will help ensure that you have the necessary altitude for deployment. Remember your airspeed limitations. The rest of us may find it harder to keep our cool after the fan stops turning, but that doesn’t mean it’s impossible.

Assuming you do have the altitude to try a restart, please remember to go through all the steps, even those usually simulated during training. A student pilot ran one tank of her Cherokee dry on a solo cross-country and dutifully ran through the drill exactly as practiced with her instructor: mixture full rich, fuel pump on...and touching the fuel selector without turning it. (She made a clean off-field landing and walked away unhurt.)

Two cases in which you definitely shouldn’t attempt it are when the engine’s plainly coming apart—you heard loud bangs, saw solid objects launch themselves through the cowling, or maybe have oil all over the windshield—and when you shut it down yourself. Why would you do that? Perhaps it was on fire, in which case landing under power takes a back seat to starving the flames before they reach the cockpit. Shut off the mixture, fuel selector, mags and master switch. Maybe a sudden, terrifyingly violent vibration announced that part or all of a propeller blade decided to seek its fortune elsewhere. The resulting imbalance can wrench an engine right off its mounts, moving the center of gravity behind the cockpit and making the airplane uncontrollable. If the level of vibration’s beyond all prior experience, go straight for the mag switch and don’t consider restarting unless you can verify that the propeller’s actually intact.

The limitations of the reporting system make hard data elusive, but there’s evidence that power losses are more often partial than complete—and even total shutdowns usually give advance warning rather than happening abruptly. This means that recognizing—and acknowledging!—incipient problems while there’s still time to turn back greatly improves survival prospects compared to pressing on until the trouble becomes unmistakable.

A bad mag check, any unusual roughness under throttle, or takeoff performance noticeably below what experience and the POH lead you to expect are all reasons to turn around and troubleshoot on the ground. If burning off a lead-fouled plug provides a normal magneto check, you may be good to go, but this might still justify rescheduling that planned single-engine IFR flight over the mountains at night. And concluding that “It seems okay now” isn’t a substitute for having actually found, evaluated and (if necessary) corrected a specific problem. If whatever it was could just go away, it can probably come back again.

Upstream of all this, of course, is the imperative to prevent problems with timely maintenance and detect any that slip through via conscientious pre-flight inspections. Assume the machine’s unairworthy until proven otherwise. Fuel samples, anyone?

The presumed safety advantages of flying a twin are another area in which intuition doesn’t match aerodynamic reality. The saying that the second engine keeps you aloft just long enough to reach the crash site is only a slight exaggeration.

Not only do most light twins struggle to maintain altitude on one engine when loaded anywhere near maximum gross, but the aerodynamics of a conventional twin (think anything besides a Cessna 336/337) make precarious situations even trickier. Engine failures just after takeoff are actually more frequently fatal in twins thanks to asymmetric thrust on the good side fighting increased drag from the windmilling engine. At low airspeed and high angle of attack, maintaining control authority may actually require reducing power on the good engine while pitching down to recover airspeed. Without enough rudder to keep the airplane pointed forward, the increased thrust and lift from the good engine will roll it onto its back.

Even in cruise with power to spare, any engine failure warrants an emergency declaration and request for vectors to the nearest suitable airport. There’s no certainty that whatever shut down #1—fuel contamination? maintenance errors?—won’t catch up with #2 sooner rather than later.

David Jack Kenny has never had an engine issue he couldn’t fix. He’s a fixed-wing ATP with commercial privileges for helicopters.

This article originally appeared in the March 2019 issue of Aviation Safety magazine.

For more great content like this, subscribe to Aviation Safety!