The year 1979 was the last big year of aircraft shipments. Almost 18,000 were sold that year. About 3,000 of those airplanes were piston twins. Today, any single that sells 534 units a year is red hot. In 1979, that's how many Seneca twins Piper sold. If the piston single business looks lethargic when compared with the good old days, the piston twin is practically extinct. Beech builds a few Barons, and Piper some Senecas and Seminoles, mostly on special order. The Diamond Twin Star, which is a diesel twin, and the Adam 500 are just coming on line. In 1979 there were 33 different piston twins on the market.
So, what happened? Why did piston twins virtually go away? Will they come back? It is an interesting story.
New-design piston twins started coming to market in 1952 with the Twin Bonanza and Aero Commander. (The Beech 18 had been around but was in a different class.) The 310 and Apache followed shortly and then more models were added every year for the next 20 years.
Back in the 1950s and '60s, virtually all pilots who went beyond a private certificate also got a multiengine rating. The usual progression was private, commercial, multiengine, flight instructor and then a few would get an instrument rating, which was not a big thing at the time.
Twin training was available at almost every airport and was most often done in Cessna T-50s, Bamboo Bombers, surplus World War II airplanes powered by round 225 hp Jacobs engines. Almost every FBO had one and they were used primarily for training or rental. I'd add that the airplane had two engines because it needed them. There wasn't a best single-engine climb speed. Instead, there was a single-engine speed for minimum sink.
There were also legions of WWII pilots and those who had flown transports and bombers were both multiengine qualified and rated, and they liked airplanes with more than one engine. At the airports where I flew, many of the WWII pilots who were flying GA airplanes were transport/bomber guys; most fighter pilots seemed to have had enough.
So, when new piston twins came along there was a ready and eager market. I heard a lot of pilots say, after flying an Aero Commander or 310, that they had no intention of ever again flying a single-engine airplane.
Aviation was much into myths at the time. Two of them were that twins were far safer than singles, plus, that any red-blooded American pilot would "step up to a twin" as soon as he could afford to do that. It was a natural progression from a beginning airplane to a high-performance single to a twin (and later to a turboprop and then a jet).
The available information on accidents was sparse at that time and most opinions were formed based on what we saw and experienced around the local airport. Twins certainly seemed like they would be safer. The first tarnish that I saw on the reputation of the twin came in July 1958. I lost three friends when a Beech Travel Air flat spun to the ground on an FAA multiengine check ride. That accident was followed by many more like it, mainly in Travel Airs, Barons and Piper Twin Comanches.
The cause of all these similar accidents related more to an insane FAA requirement (do minimum engine-out control speed demonstrations as low as possible, but not below 500 feet above the ground) than to the airplanes. It was as if the FAA just wanted to certify survivors to fly twins. It took a long time and a lot of effort to bring sense and logic to the FAA on this subject.
These training accidents didn't discourage those who wanted a twin. The airplanes enjoyed continuing success and most pilots were still convinced they were safer. Twins had a bad record maybe in training, but much better after that.
The insurance companies were convinced, too. My father and I had been flying a 250 Comanche and switched to a Twin Comanche in 1964. I was astounded when I transferred the insurance. The twin's insurance was a lot less costly than the single's. Was that based on perception or reality?
