SOCATA TBM 700

A recent tragedy that resulted in two fatalities from a crash of an airplane that I’m not familiar with, a SOCATA TBM 700, impacted a wooded area near Pembroke, New York, October 2, 2020. A prominent attorney in the Buffalo, New York area, and his niece were the only people on board, and thankfully no other injuries are reported at the crash site. My heart is heavy with sorrow for the family, and I extend my thoughts during this most difficult time. My family and I personally experienced similar hardships, more than I would care to remember, but I find that time is a great healer, allowing us to cope better and understand our loss.

In 1990, the TBM 700 series entered the civilian aviation market as the first certified, both with the FAA and French DGAC (EASA), pressurized single-engine turboprop aircraft in the world, labeled as the TBM 700A model. A list of impressive features includes; a 1305 nautical mile range, a maximum cruising speed of 300 knots, a useful load of 1347 pounds, and a short take-off or landing field length of 2133 ft. The TBM 700 can easily land on a 2800 ft runways or less, making this airplane far more accessible to shorter strips than business jets. Couple this with the capacity to carry six passengers in a luxurious cabin, and the Canadian’s performance made Pratt & Whitney PT6A-64 turbine engine; the result is a legendary performer. The PT6A-64 has a thermodynamic power rating of 1570 ESHP with a flat rated power of 700 shaft horsepower. A 91″ diameter Hartzell four-bladed hydraulic propeller provides the thrust with constant speed, automatic full feathering, and reverse thrust control. The minimum landing distance is reduced to 1640 ft using reverse thrust. Net weight is 4100 pounds with a maximum take-off weight of 6579 pounds. The climb rate is 11 minutes 45 seconds to 20,000 ft and 20 minutes 30 seconds to the maximum certified ceiling of 30,000 ft.

Let’s take a moment to talk about turbines and the differences between a turboprop engine, like the one used on the TBM 700, and a turbofan engine used on most commercial airliners that we are most familiar with seeing. Think of your classic commercial jet airliner and the two turbofan engines, one mounted on each wing.

When ignited fuel exits the combustion chamber, the high-pressure explosion is forced through the rear turbine, causing it to spin, driving the shaft-mounted front compressor blades and duct fan, which in turn produces thrust, in very simplified terms. The rearward thrust propels the aircraft forward, creating lift generated by the wings and allowing the flight’s fundamental principle.

A turboprop engine is similar to a turbofan engine except that the shaft connected to the rear turbine spins a front reduction gearbox, in place of the duct fan, that turns the propeller. I know it’s a bit more complicated than that, but I think you get the idea. Why am I bringing this up, you ask? Because I feel it’s important to understand what a turboprop engine is and why the TBM 700 series aircraft uses it instead of using the more common piston engine found on smaller single-engine airplanes.

Turbine powered airplanes can fly at high altitudes. The desired operating height is between 20,000 and 30,000 ft to optimize the relatively low-efficiency rate compared to a piston engine plane, which is usually limited to under 15,000 ft. Turbine engines are smaller and lighter than comparable piston engines and are more reliable. They are also more expensive because of the high-quality parts used and rigor needed to produce this appreciable power plant. The TBO or time between overhauls is extended for a turboprop because it consists of fewer moving parts than a piston engine, meaning less downtime between flights. Turboprop engines use superior metals to withstand the high operating temperatures and extreme turbine revolutions requiring precision balancing, which factors into the higher costs over a piston engine. Fuel is another benefit of a turboprop where jet fuel is more readily available than typical avgas used in piston engines, making refueling easier during long flights.

The TBM 700 series’s airframe consists of incorporating various aluminum and steel alloys, including titanium. Advanced composite material strengthens the airframe’s structural integrity, allowing durability at the lowest possible weight while maintaining reduced manufacturing costs. Failsafe engineered techniques incorporated on all TBM airframes include using multiple load paths, a crack-stopper band, and minimizing the number of small access panels to maximize sub-system reliability and structural life.

In 1992, the French Air Force and French Army Aviation received the TBM 700A model aircraft delivery from SOCATA to replace the obsolete Morane MS 760 Paris Jet. The French military pilots reported that the TBM 700A is “simple to master, a dream to fly and superior performance characteristics across the entire flight envelope.” The French Armed forces have also operated the TBM 700A in varied environments, including combat zones, accumulating around 600 flight hours per plane annually, accomplishing a wide range of light cargo and VIP passenger missions. The French national flight test center (CEV) also received a TBM 700A along with an order of three delivered to the Indonesian government for their country’s airfield navigation aid calibration.

In 1999, the TBM 700B model’s introduction showcased a sizeable cargo door with an added pilot entry door as an option. The French Army Aviation adds three 700B models to their fleet, increasing the total service to 28 aircraft in 2002. The certified ceiling raised to 31,000 ft due to the addition of a gaseous backup oxygen system with EROS quick donning masks.

2003 is the last year of upgrades to the TBM 700 platform with the TBM 700c2 model. The maximum take-off weight increases to 7394 lbs with a payload increase of 865, including full fuel tanks and a rear external luggage compartment. The model 700C, which precedes the 700c2, is identical except for lacking the reinforced landing gear, which reduces the maximum take-off weight and the 20G cabin seats. The structural modifications of the 700c2 include a reinforced airframe, a strengthened landing gear, seats certified to withstand 20G’s in the event of a crash, upgraded avionics, and a new cabin environment that sets the standards in executive travel.

The TBM 700 platform is so successful that EADS SOCATA launches the TBM 850 Legacy in 2006 using an identical airframe. Still, featuring a turboprop engine, the new Pratt & Whitney PT6A-66D replaces the PT6A-64 and increases the ratings to 1825 ESHP with a flat rated shaft horsepower of 850.

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I would end this article with the TBM 700c2, but SOCATA has such an exciting past that I couldn’t resist the urge to dive deep into their history. We will need to go back to the early 1900s, a time that I find so fascinating since I started investigating the news clippings in my father’s scrapbook, and I hope you’ll join along for another stroll down aviation history lane.

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Morane-Saulnier formed the French manufacturing company on October 10, 1911, when Raymond Saulnier composed a partnership with the Morane brothers, Leon and Robert. Saulnier previously worked for Louis Bleriot as an engineer starting in May 1908 but decides to leave in October 1909 to form his short-lived airplane company, demised with a financial burden. While working for Louis, he helped design the Bleriot XI, where Louis successfully flew it 22 miles across the English Channel from Calais, France, to Dover, England, on July 25, 1909, in 36 minutes 30 seconds. Louis is instantly famous, becoming the first person to fly an airplane across the English Channel! Saulnier later meets Bleriot pilot Leon Morane towards the end of 1910 through his business associate, Gabriel Borel, representing the Bleriot plane. He soon meets Leon’s brother Robert, and the three agree to form the successful Morane-Saunier company.

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Eager to beat Louis Bleriot’s English Channel flight, Saunier begins working on a new design, the Morane-Saulnier type H airplane and completes a test flight in early 1912. The aircraft is a great success, and on September 23, 1913, company pilot French aviator Roland Garros completes the first non-stop flight across the Mediterranean from Frejus, France, to Bizerte, Tunisia.

Garros enlisted as a pilot with the approaching World War and soon began working on arming a plane. He was tired of trying to shot the enemy planes with his pistol while on reconnaissance missions. There he modified a Morane-Saulnier type L parasol monoplane by installing a Hotchkiss machine gun firing 8mm solid copper bullets through the propeller’s rotation. The only problem, and a major one, is the lacking of a mechanized timing system between the machine gun and the propeller’s rotation preventing the bullets from striking the prop. Garros realizes this is a problem, to say the least, and adds triangular steel plates to the propeller blades to deflect any bullets that may hit. This technique was not very efficient but still gives Garros the upper hand in piloting a more lethal aircraft than his enemies at the start of the war. Saulnier is impressed with Garros’s design that he files for a patent in April 1914.

In April 1915, Garros tested his new machine gun design during actual air combat and obtained three victories in fifteen days. Unfortunately, his luck didn’t last long, and he finds himself behind enemy lines when German anti-aircraft fire damage his plane while flying over Belgium. With no time to destroy his aircraft and keep his machine gun design secrete, German soldiers, capture him becoming a prisoner of war for three years. The Germans can now study his machine gun design on his damaged aircraft, which they ship off for Anthony Fokker to examine. Fokker is currently under contract to build airplanes for Germany, the Fokker Eindecker, and asked to add this machine gun design to their planes. At first, he notices the simplicity of the metal plates mounted onto the propeller blades, but then instantly realizes the solution is to have the propeller fire the gun. Since the propeller rotates at 1200 rpm and the gun fires at 600 times per minute, Fokker decides to add a cam off of the engine crankshaft to fire the gun every other turn. Brilliant! And in three days, he has developed a synchronized machine gun system capable of firing bullets cleanly through a spinning propeller.

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Raymond Saulnier designed many airplanes for his company, and Morane-Saulnier produced more than 140 models with a significant number produced between the two wars. Perhaps the most recognized are the MS 130 from the 1920s and the MS 230 from the 1930s, but I am particularly fond of the 1914 type N Bullet.

In 1938, the MS 406 debuts as a famous French fighter and were France’s most numerous aircraft during WW II, capable of over 300 mph with a dive speed over 450 mph without any structural failure. The MS 406 also incorporates Saulnier’s patented sliding ejectable cockpit developed in 1937. I hope the pilot’s uniforms came with an extra set of pants!

After testing in 1954, Morane-Saulnier introduced the twin-turbine MS 760 Paris in February 1959 as the first four-passenger jet sold as a military trainer or civilian business plane. Variants include the MS 760B Paris II and the MS 760C Paris III.

Raymond Saulnier manages to operate his company for more than fifty years successfully but decides to fill for bankruptcy in 1962 due to decreased sales. Henry Potez took over the bankrupted Morane-Saulnier on January 8, 1963, and after a short period, becomes a subsidiary of Sud-Aviation on May 20, 1965. The name changed in 1966 to SOCATA, an acronym for Societe de Construction D’Avions de Tourisme et D’Affaires or “Company for The Construction of Aircraft for Tourism and Business.”

Multinational aerospace conglomerate EADS purchases SOCATA in 2000 as a solely owned subsidiary and rebrands the company name to EADS SOCATA. Daher, a French technology business, negotiates a deal with EADS to purchase 70% of its shares on November 3, 2008. In June 2014, Daher acquired the remaining shares from EADS and rebranded the company in March of 2015 from EADS SOCATA to Daher.

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The name Henry Potez should be familiar to you because I touched briefly on him and his Potez 25 biplane that Jean Mermoz flew over the Andes Mountains in 1929. If not, read more about him in my post, Tony’s Scrapbook; Jean Mermoz.

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