Suddenly Single

In the world of multiengine jet training, a lot of time is spent preparing for the loss of an engine at the worst possible moment—right at the V1 decision speed. But the amount of time spent at that point during any flight is small. Statistically an engine failure is most likely to happen during the cruise portion of the flight, when there’s usually plenty of time and altitude to deal with the problem. Let’s review the basics of what will happen and how best to handle the loss of an engine at altitude.

The mere thought of a full-on uncontained catastrophic engine failure with high-speed turbine blades flying everywhere is scary, but fortunately that kind of failure is extremely rare in the world of light jet operations. Most engine shutdowns are the result of more subtle problems. The failure of a connector in a high-temperature bleed-air line in an engine nacelle can trigger a fire warning—or worse. Bleed air temperatures can be high enough to deform or even melt metal parts and start a fire if the engine isn’t shut down in a timely way. A fire that starts in an engine requires cutting off fuel, which will shut down the engine. If a starter-generator bearing comes apart, it can induce violent, large-amplitude vibration that requires quick action to cage the affected engine. A blown seal in a main shaft bearing may cause rapid and catastrophic loss of oil pressure accompanied by rising engine temperatures, which must be handled with an engine shutdown. There are certainly more ways to lose an engine, but in general, the signs of a problem start with an abnormal noise, unusual vibration, a high temperature warning, or unusual engine operating parameters.

In almost every case, if you are in the flight levels and you have an indication of an engine problem, the first thing to do is to don your oxygen mask. Take the time to ensure that the cabin pressure is holding and the situation is stable before removing the mask. If you are losing pressurization, your memory items should include dropping the masks for your passengers. Second, pull the emergency checklist and follow the procedures to handle the situation. If you have to shut down and secure an engine and you are above the single engine drift-down altitude, you are going to start a descent whether you like it or not. Stay ahead of the situation, retrim the airplane, and use the autopilot to hold VYSE at your current weight to minimize the descent rate.

At this point it may feel like things are under control, but the loss of an engine in a twin-engine airplane is generally considered an emergency. Don’t be shy—tell ATC you are headed down and declare an emergency. It’s important to understand that losing an engine and its associated bleed air and electrical systems brings into question the airworthiness of the aircraft. FAR 91.7(b) has been interpreted to mean that any unairworthy mechanical, electrical, or structural condition that develops in flight requires a deviation to the first available and suitable airport. A suitable airport is one that permits a safe landing, so you are not required to choose the first available airport. Weather and runway length will play into selecting a suitable airport. A spare operating engine opens up a lot of possibilities in the face of poor weather conditions or sparsely populated areas, so pick an airport with a reasonably long runway and pretty good weather. Just keep in mind that the FAA will probably take a dim view of shutting down an engine and tooling along at the driftdown altitude while passing up a lot of perfectly suitable airports simply to make it to the nearest service center 200 nautical miles away. Take care to avoid any action that could be viewed as a careless or reckless under FAR 91.13(a), but more than that, make safety the top priority.

At this point, there are a couple other things to consider. First, remember to manage fuel balance. If the operating engine is pulling fuel from only one of the wings, you’ll probably have to start transferring fuel around to avoid a lateral load imbalance. The second consideration is whether to try an engine restart. It is extremely rare for a modern turbofan engine to simply conk out for no good reason, so think hard about this one. About the only time to try a restart might be if the engine appeared to have stopped with little indication of cause and there are dire consequences of descending to the drift-down altitude. Just remember that you generally have to descend quite a way before attempting an air-start.

There are some circumstances in which losing an engine at altitude can turn more serious. Think about losing an engine over the north Atlantic. Not only will you be dragging along a dead engine, but you’ll be drifting down to a lower altitude where you might wind up in crummy weather, sucking more fuel, with greatly reduced range. This scenario should always be a part of the preflight planning process for any oceanic crossing. A good plan should include single-engine turn-back points and the availability of alternate airports, taking into account the predicted weather conditions for any unplanned single-engine operations.

It’s easy to take for granted the capability of most light jets to sail over the top of some pretty large storm systems. Keep in mind that losing an engine above any widespread thunderstorm activity may drag you through the worst high-altitude parts of the storm. If the weather is strong and widespread, think hard about your options if you lose an engine. Sometimes a small deviation isn’t such a bad strategy, even if you can clear the tops by safe margins.

FAR 830.5 requires immediate notification of the NTSB for an in-flight fire or the failure of the structural components of a turbine engine excluding compressor and turbine blades. So, if there’s an engine fire or an engine falls off the airplane, you’re going to have some paperwork to do, but for most engine failures, there isn’t any requirement for an NTSB report.

Fortunately, modern turbofan engines are remarkably reliable, so most of us will fly for a lifetime without ever experiencing an engine failure outside of the simulator. If it ever happens, stay calm, remember your training, and stay safe out there.

John Hayes is an optical engineer. He is an ATP, CFI, and type rated in Cessna C500 and C510 Citations.