By Neil Singer
A large amount of the time spent training to fly a jet involves simulated engine failures. Engine failures during the takeoff, en route, approach, and even go-around phase are repeated ad nauseum until the pilot can maintain control, deal with the problem, and fly an approach to either a landing or—more often—a go-around for another trip around the pattern.
Yet for all the drilling in initial training, most pilots will fly their entire lives without having an engine fail in a jet. During the year that passes between recurrent training events, the skills to manage engine-out flight often atrophy severely. That’s why it’s common to see engine-out maneuvers as the largest focus of recurrent training and proficiency checks.
Flying an airplane on one engine is a demanding stick-and-rudder task. To begin with, an axis most pilots normally give little thought to (the vertical axis) is now the most demanding of attention. Even when hand-flying a jet, a pilot will nearly always have the yaw damper engaged to take care of that pesky rudder coordination job. Furthermore, jets don’t tend to exhibit the same level of adverse yaw characteristics as light airplanes, so even without a yaw damper turned on, pilots can get away without adequate rudder inputs and not notice they are being lax.
Of course, this situation doesn’t hold true for one engine inoperative (OEI) flight. Now the thousands of pounds of thrust pushing from a station off to the side of the longitudinal axis of the airplane create an unmistakable yawing force away from the operating engine. First-time jet pilots are often shocked to see how much rudder force is required at high thrust settings and low airspeed, especially during takeoff, when flying OEI. Looking at how close the engines on light jets are to the aircraft centerline, they can be forgiven for thinking the yawing force should be easier to manage than in a piston twin, with its engines out there on the wings.
The first tip pilots flying OEI must keep in mind is that rudder input is only static if thrust and airspeed are unchanged; every power or airspeed change requires a readjustment of rudder pressures and trim position. As soon as the aircraft levels off from the takeoff climb, for example, thrust will be reduced while airspeed starts to build rapidly. If the pilot doesn’t react with a smooth and significant release of rudder pressure, the aircraft will end up flying in an uncomfortable sideslip. A helpful image to keep in mind during power changes is that of a direct connection between the operating engine’s thrust lever and the corresponding rudder: If the thrust lever is advanced, the rudder should be as well, and vice versa.
A pilot can reduce the yawing effect of OEI flight with proper fuel management. Keeping in mind that the cause of the yaw is the presence of an arm (distance) between the engine’s thrust line (more or less the center of the engine) and the aircraft’s center of gravity (CG), it’s apparent that anything that can be done to reduce that distance will make the aircraft tamer. While we can’t move the engine, we can move the CG laterally with fuel transfer.
The difference in lateral CG between a 200-pound fuel imbalance with the heavy tank on the operative engine side (a good thing), or on the failed engine side (a bad thing) is significant—and results in a noticeable improvement in handling characteristics. For this reason, rather than balancing fuel so the wing tanks’ fuel levels are even, it’s better to burn fuel down to an imbalance, with more fuel on the operative-engine side. When an engine goes out, the pilot will be much happier by transferring fuel into the “good tank” to the maximum imbalance level allowed, and then burning down toward balance from that point.
Speed control is another area where pilots can make their lives dramatically easier when flying OEI. At high airspeed, the rudder is more effective, and the aircraft is on the “front side,” or speed stable side, of the power curve. Slowing down prematurely on an approach is a common cause of dramatically increased workload and/or sloppy performance. Gradual speed reductions and, when possible, delaying configuration changes until on the glideslope will allow the pilot the most time to smoothly adjust rudder inputs, and to make corrections if too much speed begins to bleed off.
Slowing below VREF is to be avoided at all costs. When configured for an OEI landing, a fair amount of power is needed to simply maintain a three-degree glideslope, and nearly full power may be needed to sustain level flight. In other words, there’s not much thrust remaining to increase speed should it fall below VREF. Any excursions below VREF must be immediately and aggressively fixed as soon as they’re detected—before they become uncorrectable.
A single-engine go-around is perhaps the most demanding task on a type-rating checkride or proficiency check. The initial transition from approach to climb airspeed control is especially important. In heavy, hot, and high-density-altitude situations, even full power may not be enough to initially arrest a sink rate. The pilot must avoid the temptation to pitch up excessively in an attempt to force a climb. Instead, wait while the engine spools up, and the initial flap retraction is made. This will help lower drag and make a climb possible.
Once a climb, however meager, is realized, the gear should be retracted, and now the pilot will be faced with an opposite challenge: pitching up. The quick drag reduction as the gear fully retracts necessitates a smooth, and sometimes aggressive, pitch up to maintain a climb. Many pilots have struggled with the timing of pitch changes during an OEI go-around. They get too slow during the first few seconds of the maneuver, then quickly build up airspeed once the gear is up—and don’t get an adequate climb rate. Keep in mind this is all occurring as rudder forces on the aircraft are dramatically changing, and it’s easy to see why the OEI go-around can quickly saturate pilot workload.
Neil Singer is a Master CFI with more than 9,500 hours in 15 years of flying.