Why the FAA Almost Banned This Plane: The Mitsubishi MU-2 Story

The Mitsubishi MU-2 is one of the most unique turboprop aircraft ever produced. It's fast. Shockingly fast. It's efficient. And for decades, it was also one of the most accident-prone aircraft in general aviation. The FAA investigated it. Pilots debated it. And yet, it never stopped flying. So what is the MU-2? Why was it so controversial? And is it actually dangerous or is it simply a misunderstood machine that punishes those who don't respect it? Welcome. Today, we're diving deep into the full story of the Mitsubishi MU-2, the engineering behind it, the accidents that nearly killed it, and why a small group of dedicated pilots still swear by it to this day. Origins and History To understand the MU-2, you have to go back to post-war Japan. After World War II, Japan's aviation industry was completely shut down by Allied occupation forces. For years, Japan was forbidden from designing or building any aircraft at all. But Japan never stopped thinking about aviation. When restrictions were lifted in the 1950s, Japanese engineers were hungry. Hungry to prove that Japan could build world-class aircraft. And one company had the ambition, the talent, and the resources to lead the charge. Mitsubishi Heavy Industries In the early 1960s, Mitsubishi set out to build a small, fast utility turboprop. Something that could carry passengers and cargo efficiently at high speed over medium distances. The design brief was ambitious. This aircraft had to be faster than the competition, carry a useful load, and land in places that bigger jets simply couldn't. The result was the MU-2, which made its first flight on September 14, 1963. From the very beginning, this aircraft was unconventional. Mitsubishi's engineers made design choices that were bold, efficient, and controversial. Entering the American Market By the late 1960s, Mitsubishi partnered with Mooney Aircraft Corporation in Texas to market the MU-2 in the United States. The aircraft found a willing audience among corporate operators, air taxi services, and medevac operators. People who needed to go fast, carry a useful load, and land in places that bigger jets simply couldn't. Production continued until 1986, with over 700 aircraft built, in two main configurations, a shorter fuselage version, and a stretched version called the Marquise and Solitaire. These aircraft went to operators all over the world, from Alaska bush operators to Japanese medical services to U.S. government agencies. The Engineering Most turboprops look similar. They have conventional wings, conventional control surfaces, and fly pretty much the way you'd expect. The MU-2 is different, deliberately, aggressively different, and those differences are at the core of both its performance and its controversy. The most striking feature of the MU-2 is its wing. It's short, very short. Engineers call this a high wing-loading design, meaning the wing has a small surface area relative to the weight it carries. This is great for speed and efficiency at cruise altitude, because a smaller wing creates less drag. But here's the trade-off. A high-loaded wing stalls more abruptly and at a higher speed than a conventional wing. To compensate, Mitsubishi used full-span, double-slotted Fowler flaps, flaps that extend across almost the entire length of the wing. When deployed, these flaps dramatically increase the wing area and allow the aircraft to fly slowly enough to land safely. It's an elegant engineering solution, but it also means the flaps are doing enormous work, and the aircraft's handling characteristics change significantly between flaps up and flaps down. Ailerons Here's where things get really interesting. Most aircraft roll left and right using ailerons, movable surfaces on the outer wing. The MU-2 has no ailerons. Instead, it uses spoilers, panels on top of the wing that pop up and disrupt airflow to create roll control. Spoilers are used on many large jets, but using them as the primary roll control on a small turboprop was almost unheard of. This design choice freed up the entire wingspan for those large Fowler flaps, but it also gives the MU-2 a distinctive roll feel that pilots have to learn and respect. In normal flight, the MU-2 rolls smoothly and responsibly, but near the stall, spoilers can cause the aircraft to roll rapidly and unexpectedly. Pilots who didn't understand this characteristic, and there were many, got into serious trouble. Power came from Garrett Air Research TPE-331 turboprop engines, compact, powerful, and reliable. These engines, combined with the efficient wing design, gave the MU-2 a cruise speed of around 300 knots, faster than virtually any piston aircraft, and competitive with many jets. Early versions of the MU-2 actually had retractable landing gear, but later versions switched to fixed main gear in a unique semi-retractable arrangement. This simplified maintenance and reduced weight, though it did create some additional drag. The aircraft also sits in a distinctive nose-high stance on the ground, something pilots quickly learned to account for on takeoff. The Controversy Through the 1970s and 1980s, the MU-2 developed a troubling safety record. A pattern emerged in accident reports. Experienced pilots, people who had no business making basic mistakes, were losing control of the aircraft, often during approach and landing. The NTSB and FAA took notice, found a consistent theme. Many crashes involved loss of control, pilots entering situations the aircraft was not designed to survive, often after failing to manage energy correctly, flying the wrong airspeeds, or being surprised by the aircraft's stall characteristics. The MU-2 is an aircraft with very little margin for error at low speeds. Its high wing loading means it needs to be flown at precise airspeeds, its spoiler-based roll control can be unforgiving near the stall, and its powerful engines mean that mismanaged throttle inputs can cause rapid pitch and roll changes. In short, the MU-2 rewards precise, disciplined flying, and it punishes those who don't give it the respect it demands. In the mid-2000s, the FAA conducted a comprehensive review of the MU-2's safety record. This was a significant undertaking, and the results were revealing. The investigation found that the MU-2's accident rate was higher than comparable turboprops, but that the root cause was primarily pilot training and proficiency, not any fundamental defect in the aircraft design itself. As a result, in 2008, the FAA issued a special federal regulation, known as SFAR-108, specifically for the MU-2. This regulation mandated that all pilots flying the MU-2 complete a standardized training program taught by approved instructors, no self-study, no informal checkouts, formal standardized training, or you don't fly. Flying the MU-2. Talk to pilots who've flown the MU-2 for years, and you'll hear a distinctive mix of respect and affection. Almost universally, they'll tell you that it's not the aircraft for everyone, but for the right pilot, with the right training and mindset, it's one of the most capable and rewarding aircraft ever built. The MU-2 demands that you fly it precisely. You can't be sloppy with airspeeds. You have to understand energy management. You have to stay ahead of the aircraft, planning your descent, your approach, your configuration changes well in advance. Takeoff, the MU-2's powerful engines accelerated briskly. Rotation happens at precise published speeds. Pilots learn to be exact, not approximate. The aircraft climbs steeply and quickly, the engines singing at high power. In many ways, this phase of flight feels more like a jet than a propeller aircraft. At cruise altitude, typically in the mid-20s to low-30s in feet, the MU-2 settles into a smooth, efficient cruise. The speed is impressive. Passengers often comment on how quickly the ground moves beneath them compared to what they expect from a propeller-driven aircraft. This is where the MU-2 demands the most from its pilots and where its unusual characteristics are most apparent. The approach must be stabilized early, configured, at the correct speed, on profile. There is no room for large corrections close to the runway. The large Fowler flaps change the aircraft's handling feel significantly. Pilots learn to anticipate this change rather than react to it. Speed must be controlled tightly. Too fast and you float past the end of the runway. Too slow and the aircraft's stall characteristics can become a factor. Done correctly, an MU-2 landing is smooth and satisfying. Done incorrectly, the aircraft provides immediate and unpleasant feedback. Legacy and Today The MU-2 has developed one of the most dedicated owner and operator communities in general aviation. Organizations like the Mitsubishi Aircraft Owners and Pilots Association, MAOPA, provide training resources, technical support, and a network of experienced pilots who can help new operators get up to speed. For more UN videos visit www.un.org