Produced in 1963, the Mitsubishi MU-2 Solitaire was among the first turboprops to be produced, but also with one of the most controversial backgrounds.
Considered by some to be one of the most successful planes out of Japan. Looking through its history, this is an aircraft plagued with lots of bad publicity and negative press, most notably for its concerning safety record - over 180 crashes and 300 fatalities to date.
This streak of crashes prompted the FAA to conduct investigations into the M to evaluate its safety. But investigation conclusions rather found the aircraft fit for flight with the exception of being operated by a well-trained pilot and the aircraft being well maintained.
So why all the fuss around the Solitaire? We aim to look at what causes the MU-2 to have such bad publicity around it and still at the same time, have others depict it as competing with the likes of the Beechcraft King Air and even being as efficient as a low-speed jet.
We will look into the aircraft's build and operation from public reports submitted by the FAA and the manufacturer’s designs to answer this lingering question.
What Makes The Mitsubishi MU-2 Different?
Manufactured by Mitsubishi Heavy Industries, the MU-2 is a high-wing, twin turboprop aircraft with engines mounted under its wings (giving the propellers good ground clearance for landing on unimproved areas) and has a pressurized cabin carrying a capacity of between 7-11 passengers.
Making its debut flight in 1963, the MU-2 Solitaire had 704 units produced by the Japanese company then later, production rights were granted to Mooney Aircraft in San Antonio, Texas, before being taken up again by Mitsubishi after Mooney was faced with financial troubles.
Production continued until 1986. With various variants meant both for civilian and military use made available in the market.
The XMU-2 was the prototype built, with only one unit manufactured. It was fitted with Turbomeca Astazou Mark II engines. The MU-2A followed production as an upgrade to the prototype and had three units produced; they were also fitted with the same Astazou engines.
The MU-2B followed production having 34 units built and the aircraft was upgraded to Garrett TPE331 engines which are more powerful and fuel efficient.
The MU-2D was further upgraded to be able to operate in higher altitudes. Then later the MU-2C and MU-2E variants were specifically built with unpressurized cabins (majorly produced for military purposes).
Other variants produced by the Japanese manufacturer are the Solitaires having 57 units built and Marquise which is characterized by a stretched fuselage; these two are the most common in the market today.
This aircraft can reach cruise speeds in excess of 310 knots depending on the surrounding conditions, a considerably fast aircraft compared to others in its line.
Designed to be a turboprop airplane capable of very high cruise speeds, offering a smooth flight experience and still capable of landing and taking off on short, unimproved runways, the MU-2 is a rugged and compact aircraft.
Even though pilots have complained of it being annoyingly noisy on the ground (yes, all aircraft do make noise, but this one is an exception). This prompted the addition of a fourth propeller blade to other variants in an effort to reduce the noise.
One of the unique things that you will notice right away is its wings. This plane lacks ailerons and instead, the MU-2 makes use of over-wing spoilers to achieve roll control.
This feature has been subject to numerous rumors and misconceptions, with some saying that using spoilers for roll control is unsafe because it leads to unusual flying characteristics like the aircraft not being able to roll along its axis, instead rolling about the wing tip.
Or because it uses a spoiler system, it degrades the lift on one wing, and that wing drops instead of the aircraft rolling. These rumors though are untrue as they go against the known principles of aerodynamics.
The use of this ingenious design by Mitsubishi engineers though not a unique feature of the MU-2 as it can be found on the B-52 Bomber, P-61 Black Widow, and other modern light aircraft.
Allows the MU-2 to be fitted with double-slotted Fowler flaps which extend its entire wingspan making it capable of achieving short field takeoffs and landings by reducing the stall speeds and wing loading.
The use of this spoiler system not only gives the aircraft the advantage of being able to increase the wing surface area by giving more room for flap extension, but it is a very effective system for roll control.
It is known to achieve better roll rates than aileron-controlled aircraft, especially at low air speeds as observed by pilots.
A phenomenon experienced in aileron-controlled airplanes, the slower the airplane flies, the less effective the ailerons become. This is because of airflow separation at the trailing edge of the wing, something which is not experienced in the spoiler system.
One unusual feature that will be experienced in flight with the spoiler system is the extent of control deflection needed to achieve roll with this aircraft. The MU-2 requires a slightly larger amount of control deflection to generate roll.
The wings on the MU-2 are smaller enabling it to achieve higher cruise speeds than its counterparts in the same line by offering high wing loading which is a characteristic observed in jets.
Fitted with integral fuel tanks along its wing span, the two engines are fed by five fuel tanks, including two wingtip tanks.
Solely looking at the specs of the Mitsubishi MU-2, someone with a couple of thousand dollars to spend and wouldn’t mind getting a post-colonial aircraft (and no, its look is still very fresh and modern) this wouldn’t be a bad bargain.
So how come this aircraft got to receive such a bad reputation?
Is The Mitsubishi MU-2 Safe?
By researching the needs at that time, Mitsubishi mainly centered on this aircraft to cater to an identified corporate market that demanded fast and low-cost airplanes.
With this in mind, it gained quite some popularity in production. Especially appealing to amateur pilots, most of whom seek to upgrade from piston engines unaware of its particularly demanding nature if in the wrong hands.
At the time, the MU-2 was considered to be a light aircraft (though with the performance of a small jet), pilots rated to fly much slower multi-engine piston aircraft were allowed to upgrade with just a simple endorsement from a flight instructor, despite their inexperience.
Unknown to them, there are some flight characteristics related to this aircraft that might not be synonymous with pilots used to flying much slower piston engines.
For example, the handling qualities of this aircraft almost need no rudder input when in coordinated flight, rolling right or left, even if the control wheel is fully deflected. The spoilers virtually prevent all adverse yaw.
Also commonly taught procedures such as those undertaken when experiencing an engine failure during takeoff are counterproductive with the MU-2.
Its operation is quite similar to a jet with the same operating procedures. Reducing flaps on this aircraft leads to a crucial reduction in lift.
Instead, reducing the rate of climb while maintaining flaps is a more effective way of regaining control since the large flaps increase the lift efficiency of the aircraft by increasing the wing surface area.
At low airspeed, the MU-2 is reported to have a tendency of rolling due to reaction from engine torque if full power is applied without adequate preparation. It can rapidly roll entering into an accelerated stall which can be difficult to recover at low altitudes.
Hard landings are also a common problem with inexperienced pilots flying this aircraft due to the positioning of the main landing gear behind the center of gravity. This calls for a different landing technique which might be unknown to some, posing a really big problem.
All these factors surrounding the lack of familiarity by pilots coupled with some technical failures experienced during flight, saw the Mitsubishi MU-2 record a staggering number of crashes in its early years.
Reports of over 180 crashes (some involving high-profile individuals) prompted the FAA to look into the safety of this aircraft.
Recorded incidents with the MU-2
The MU-2 is credited to have completed a successful flight around the world without any issues, making it a very capable aircraft. However, the recorded incidents surrounding this aircraft’s past give individuals both in and out of the aviation industry quite a different image.
This streak of crashes led to its resale value plummeting and insurance premiums being driven up.
In January 1968, an aircraft departing from Joplin Regional Airport heading to Tallahassee International Airport in Florida with five occupants on board crashed on a farm at Pleasant Hope, Missouri barely an hour after takeoff.
The crash killed all occupants after the Mitsubishi MU-2B plummeted nose-first into the ground, completely disintegrating only leaving the tail section intact.
Reports state that the pilot had contacted the control tower at Joplin reporting icing on the aircraft’s wings and was turning back to land before all communication went silent. Investigation reports identified icing as being the cause of the accident.
In December 1988, an MU-2B crashed at Leonora after reportedly having suffered the effects of icing leading to the aircraft losing airspeed to the point where it stalled and spun out of control.
In January 1990, another MU-2B crashed at Meekatharra under the same conditions as the crash at Leonora, killing the pilot and one passenger.
In April 1993, a state-owned Mitsubishi MU-2 traveling from Iowa to South Dakota crashed after experiencing engine trouble killing all eight of its occupants.
Among them was then-South Dakota Governor George Mickelson and several other high-ranking state government officials. The plane crashed into a farm silo after the pilot reportedly lost control of the aircraft.
In January 2000, An MU-2B lost power on takeoff and crashed in San Antonio, Texas, killing both pilots on board.
Witness statements say there were sounds of engine backfire before the aircraft made a sudden sharp turn and hit the ground.
The investigative report cited the probable cause to be pilot error, the pilot had little experience in the aircraft, failing to maintain the minimum controllable airspeed after losing engine power during the climb.
In March 2016, after experiencing an unstable approach on landing. An aircraft carrying four passengers and two crew on board, including Jean Lapierre, the former Canadian Minister of Transport, and his family crashed in Le Havre-aux-Maisons, Quebec, killing all seven occupants on board.
While in cruise flight, the pilot modified his approach which delayed the initial aircraft’s descent, placing it above the descent profile initially planned for.
The high workload on the side of the pilot is alleged to have reduced the pilot’s awareness and judgment.
In the final moments of the flight, the pilot rapidly increased throttle to full power at a low altitude in an attempt to regain control, causing the aircraft to roll sharply and descend rapidly.
Although the pilot was able to recover from this and return to level flight, the altitude was too low and the aircraft ended up striking the ground.
In May 2017, another crash located in the Bahamas was reported after the aircraft is said to have entered into an uncontrolled descent and crashed into the water.
It’s believed that the aircraft experienced icing due to bad weather reported at the time. The pilot being fairly new to the aircraft and having achieved the required training, was unable to control the plane which resulted in the death of all four occupants. The wreckage was never found.
In July 2017, a Mitsubishi Marquise departing from Buenos Aires, Argentina entered into an uncontrolled descent shortly after takeoff and crashed into a marshy area about 17 km from the airport, killing all three of its occupants.
The pilot reportedly lost control of the aircraft during climb resulting in the crash.
These are but a few of the crashes recorded over time involving the Mitsubishi MU-2, with some periods experiencing as many as thirteen crashes within a single year. This made the aircraft seem to be plagued by crashes.
What Safety Measures Are in Place for The Mitsubishi MU-2?
The numerous crashes caused quite an uproar both in the general public and inside the aviation industry and clearly for obvious reasons. Numerous lawsuits were filed mostly against the aircraft’s manufacturer questioning the safety of this aircraft.
This prompted the FAA to form a flight standards board to try and identify what were the common factors among the accidents involved with the MU-2 Solitaire.
Looking into the events, the board found no fault with the aircraft but instead identified that pilot training as being the problem.
At the time, there were numerous different types of training for this aircraft and different checklist versions creating a problem where there was a wide variety of operational parameters for the same aircraft.
This led to the FAA recommending one standardized training program, the checklist was also to be standardized and made the same across the board. Also, the flight manual was to be updated.
Following these investigations and the recommendations made, a Special Federal Aviation Regulation (SFAR) was issued for the operation of this aircraft.
In addition to standardizing the pilot training programs, checklists, and flight manuals. Specialized annual training sessions were made mandatory for all pilots operating this aircraft.
A fully functional autopilot system was also made mandatory for any single-pilot operation.
Previous pilot experience and ratings in other aircraft could not be used as a basis for compliance with the MU-2.
Various updates have since been made to the SFAR over the years. Some of these include using continuous descent during non-precision instrument approaches compared to the “dive and drive” method.
Procedures on stall recognition and recovery and the introduction of the startle factor were also updated to the initial SFAR to improve on areas that were not captured.
The introduction of this SFAR proved to be quite the game changer for the MU-2. Since its implementation, the number of reported crashes and incidents dropped by over half compared to previous years.
Because of the positive uptake of the SFAR. Today, the MU-2 enjoys arguably one of the lowest accident rates recorded among any turboprop aircraft under this class.
This shift in reputation has contributed to increased resale value as potential buyers now consider it a safe aircraft as long as it is operated by a properly trained pilot.
The MU-2 was also issued with several Airworthiness Directives.
Two of these directives associated with flight in icing conditions (though rather aimed at the pilots and not the aircraft) require specific training of pilots before flying in these conditions.
And the other insists on a video containing critical information on recognizing the beginning of intense icing conditions and effective use of ice protection systems to be shown to pilots.
After the occurrence of a series of accidents caused by the separation of propeller blades during flight in aircraft types using Hartzell propellers, an emergency directive was issued requiring immediate propeller assembly inspection for those with over 3,000 flight hours.
Though covering other aircraft types also fitted with these propellers, it was focused on the MU-2 as it is the heaviest of the batch.
There were other directives related to nose gear cracks and the various problems associated with the engine.
In addition to the usual preflight checks of aircraft integrity, pressure checks, and fluid checks, it is crucial to ensure that the propellers are held by the start locks and set to zero pitch to ensure minimum drag during start.
In an effort to improve the aircraft’s reputation and spread awareness to help reduce the number of accidents, Mitsubishi Heavy Industries formed a seminar program called the Pilot’s Review of Proficiency (PROP) program, which regularly hosts events and seminars to educate pilots on safety and the different characteristics of the aircraft. These seminars have formed a tight community free for anyone to attend and not just MU-2 owners.
The PROP seminars which had their first conference in 1982 and were later suspended in 1986 when Mitsubishi stopped production, before being resurrected in 1994 after their positive strides in the community were noticed, are still active today and counted as being part of the MU-2 training requirements.
The seminars have proved quite effective in dispelling set mindsets about the aircraft by individuals who have just misunderstood it. Similar aircraft like the V-tail Bonanza, Piper Aerostar, and Learjet 60 also suffered the same reputation.
Another great thing worth noting about the manufacturer is the continued support still given to owners of the MU-2 despite production being discontinued. Mitsubishi Heavy Industries of America (MHIA) maintains a stock of service parts and commonly used items giving owners of this aircraft an easy time during routine maintenance.
About THE AUTHOR
After spending years watching every video I could find about flying, I finally scratched the itch and got my pilots license. Now I fly every chance I get, and share the information I learn, here.Read More About Joe Haygood