Even as late as 35 years ago, twin-engine aircraft occupied a special place in the world of light aircraft. There were more than two dozen models on the market, and the launch of an exciting new model was an important moment for the plane’s manufacturer. Pilots of every experience status north of absolute beginner were candidates to buy a twin, and buy them they did. The Piper Aztec, Twin Comanche and Seneca, the Beech Travel Air, the Barons models 55 and 58, the jaunty high-spirited Duke and the lower-cost Duchess were all popular models. Cessna, with its uber-popular 310 (and derivatives), the cabin-class pressurized 421 Golden Eagle and the 340, among a handful of others, filled the market to bursting, along with the oddball but very popular 337 push-pull twin.
In 1979 alone, U.S. manufacturers delivered 2,843 piston twins, the high watermark for the decade, during which American plane makers never delivered fewer than 1,000 piston twins in any given year.
The reason was not just that these planes offered the security of a second engine, though that was their primary selling point. Other big draws were combinations of a twin’s often-higher speeds, greater hauling capacity and larger cabin.
One can debate the safety merits of twin-engine light aircraft vis-à-vis single-engine models endlessly, and just such a debate has, indeed, been ongoing in our community for the better part of a century. But for much of the earlier part of that conversation, there were a few assumptions about twins that were later called into question.
The first is that big one, that twins are safer, an assumption called into question back in the 1970s by a few somewhat informal studies that concluded that twin-engine safety was largely a myth. The reason was hiding in plain sight. With a single-engine airplane, when an engine (the only one) quits, you’re going to land somewhere, somehow. But in a twin, the argument has always gone, you get to keep on flying. Unfortunately, that has not always led to brochure-worthy outcomes. The loss of an engine in a twin is especially dangerous when the engine goes on takeoff or climb out. If not handled quickly and properly, these engine failures usually result in an unsurvivable rolling crash into terrain or airport buildings.
That’s why so much of the initial and recurrent training we do in twin-engine aircraft is with one engine caged. Twin-engine pilots need to learn how to respond to such emergencies by second nature because the time it takes to think things through when your twin loses an engine at low altitude is usually not fast enough to survive the failure.
So, the argument goes, given that singles don’t have such a critical failure mode, and given that relatively few fatal accidents are caused by the loss of the single’s one powerplant, one’s odds might just be better in a single than in a twin, at least in that regard. Then again, the counterargument goes, all of the engine failures in twins that result in a safe landing somewhere never make it into the accident statistics, so the lives saved by that second engine are certainly greater than we know or have ever known.
Many of today’s twin-engine aircraft, however, are safer in design in a number of ways from earlier models. Counter-rotating props eliminate the problem of one of the engines being more dangerous to lose than the other. Some new models feature full digital authority engine control (FADEC) and will automatically feather the prop (align the blades with the airflow for minimum drag on the dead engine). And all new-production twins feature more crashworthy structures than were required in the glory days, so some crashes are more survivable today.
There are, as you are doubtless aware, fewer than 10 twin-engine models in current production, some of those built in very small numbers. Piper did not sell any of its once-popular Seneca models last year, and Beech sold 15 Barons. Worldwide, twins accounted for fewer than 100 sales, and that has been the case for nearly 20 years now.
Twins still have their fans. Buyers of Beech Baron G58s and Diamond Aircraft DA-62s are shelling out well over a million for one of these gems, and they do so not only because they believe in the additional redundancy, performance and utility these planes offer, but also at least in part because multi-engine aircraft ownership still carries with it a level of status on an altogether different plane.