Could an airplane hit the bull's-eye more squarely in today's environment than the TBM 850? I don't see how. The turboprop single burns about half again as much fuel as a typical piston twin, but it flies at least 100 knots faster on that fuel. And its range easily stretches out over 1,200 nm even with a little headwind. And now it has the latest in avionics technology with a three-display Garmin G1000 integrated system that features the giant 15-inch multifunction display (MFD) in the center.
The TBM has been popular as a rapid personal transportation airplane for years, but with the 850's top cruise of 320 knots while burning 65 gallons an hour of fuel that more and more costs $8 and up per gallon, the airplane offers an almost unbelievable speed return for the fuel. Pull the power back a little and you can cruise at 280 knots or so on about 50 gallons an hour. But around the airport it slows down to the same airspeed, and thus same pilot demands, as a high-performance piston single.
Socata introduced the 850 in 2006 when it increased cruise shaft horsepower from 700 to 850. That extra power added about 20 knots to top cruise speed and made the airplane even more desirable. But it was not possible at that point to also update the avionics to a fully integrated glass cockpit because the technology at the right price and size didn't exist. Now it does, in the form of the G1000 system.
The 850 is actually one of the last production single-engine airplanes, piston or turboprop, to convert to a glass cockpit, but unlike some others, the conversion is complete with a crew advisory system (CAS).
Turbine-powered airplanes have a warning and caution panel made up of individual annunciator lights, and master warning and caution lights. Each light is there to alert the pilot to a problem or to indicate the status of airplane systems. Warning lights, in red, are reserved for urgent information such as low oil pressure. Amber lights indicate an abnormal condition such as pitot heat not energized. The master warning or caution light comes on to alert the pilot to look at the individual lights in the annunciator panel. Each of these lights is fundamental to the airplane certification, so an equivalent method of alerting the pilot must be demonstrated before anything can be changed.
Because of the complexity of the warning and caution annunciation system, most turbine airplanes have kept the old-fashioned lights in place when they converted to a flat glass display for flight and engine instruments. But not Socata with the TBM 850. The company spent the many months and much money to convert the system to a plain language CAS that shows warnings and cautions on the flat-panel displays. This is a big deal in terms of effective crew alerting, and also in cleaning up the cockpit. In the new 850 the three big flat glass displays show everything needed to fly and monitor the airplane in plain language, leaving only the master warning and caution lights to call attention to the messages. That's why the 850 glass cockpit looks so clean and modern compared to some others that have converted from steam gauges to glass.
The TBM also has complete redundancy in attitude-heading reference (AHRS) and air data computers, as well as in displays. With dual AHRS and air data computers they can monitor each other and warn of discrepancies that would indicate a failure. If a sensor quits, the pilot, and autopilot, can fly on by using the operating sensor from the other side of the cockpit that can display accurate information on both PFDs. And, of course, an independent attitude gyro, airspeed indicator and altimeter are located right in front of the pilot to backup everything.
Following the best human factors, the TBM 850 has its flight guidance panel mounted in the center of the glareshield. The flight guidance panel contains the controls to select heading, altitude and all autopilot modes and is a place you look very frequently in busy airspace, so you want it up where you can see it without diverting your attention from the PFD and the view out the windshield.
As with other systems in the G1000 family, the avionics in the TBM 850 can be operated using knobs and buttons on the edges of the displays. But the 850 also has a remote keyboard control unit that, by pressing buttons and turning knobs on the unit, can be used to operate most functions of the system. I like having both data entry methods. For some chores, such as entering the alphanumeric characters that define a waypoint, the keyboard is fast and handy. For other chores, such as selecting display modes or map range, I find the knobs work better. And in bumpy air, a knob is almost always easier to grasp and use accurately than a keyboard.
Socata also used the production block point change for the avionics to convert the air conditioning system to an engine-driven compressor from an electrically powered unit. The engine-driven compressor delivers dramatically improved cold air flow immediately after engine start. The cold air -- or warm air, as required -- is controlled by separate systems for the cockpit and cabin. Now a pilot baking in the sun won't need to freeze a rear-seat passenger who is sitting in the shade.
The newest 850 also has just over 100 pounds more fuel capacity because of some changes around the filler port. The landing gear has also been beefed up to handle the twisting loads of tight turns on the ramp. There haven't been gear problems in previous versions of the airplane, but ways to strengthen the gear to withstand fast, sharp turns on the ramp without a significant weight penalty were identified.
Despite its enormous capability -- or more accurately because of it -- the new G1000 system saves a little more than 100 pounds of weight in a typical 850. Some of the weight savings comes from the consolidation of dozens of flight and engine instruments into the three glass displays, but much of it results from savings in wire weight. Most of the sensors in the G1000 systems are modules that connect to the rear of the displays. In the previous system each sensor, whether it be for GPS/nav/comm or attitude, had to be linked to a dedicated display by wire bundles. In the earlier airplanes the autopilot is a distinct system with need for wires to connect it to all sorts of equipment including air data, attitude, nav sources and so on. Now the GFC 700 autopilot is essentially built into the G1000 system with need for wires to link it to only a few remote elements such as the servos.
As I walked around the new 850 preparing for flight I was again impressed by the obvious strength and purposeful nature of the design. The wing is quite thick with a nearly constant chord. But with a span of more than 41 feet the aspect ratio is high. That's what you want for an airplane to climb quickly to its certified ceiling of 31,000 feet, but still deliver predictable low-speed flying qualities and stall characteristics. The wing was designed from scratch for a specific altitude and speed profile and delivers with minimum compromise.
The large cabin door that was originally designed as a utility door offers easy access to the cabin. Seats -- even though they meet all of the latest crashworthiness G-loading standards -- can be removed by pulling a couple of pins. Many TBM owners find it convenient to fly without the left-side rear-facing center row seat, making it easier to reach the pilot seats and giving rear-seat passengers more room. Socata is building some TBMs with a forward pilot door, which some people love and others are happy to do without. The pilot door's weight chews up nearly all of the gains from the G1000 system and adds nearly $90,000 to the price. I would happily live without it. The already comfortable interior of the 850 has been upgraded in the new model with excellent leathers.
Socata chose to use the pilot's PFD in a composite mode as the initial startup display. In composite mode both engine and flight instruments are combined on a single display just as they would be if a display failed in flight. With this display you see the engine instruments to monitor the start, while the AHRS is aligning. When you turn on the avionics power, the rest of the system comes to life. The big MFD can display system synoptic pages so you can check the operation of the electrical system with its multiple buses and dual generators, or look at a detailed fuel status page. The CAS messages tell you what's left to do before takeoff, such as turn on pitot and stall warning heats.
For takeoff in the new 850 it is recommended that you still trim the rudder pretty far right to an index mark on the scale using a rocker switch under your thumb on the control wheel. This counteracts propeller effects on takeoff and initial climb. However, once in flight with the rudder trimmed a new automatic rudder trim feature of the G1000 yaw damper takes over and keeps the rudder trimmed for the remainder of the flight.
The TBM 850 flies like any other powerful single, except that it has more power than most. With 130 knots selected in the FLC (flight level change) mode the long nose points to the sky and keeps going up. On a standard temperature day the airplane can get to 25,000 feet in about 14 minutes. Pretty good for only one engine. And all 850s are eligible for RVSM approval so they can fly up to the certified ceiling of 31,000 feet instead of the maximum 28,000 feet for non-RVSM airplanes.
Socata converted the 850's cabin pressurization controls to an electronic system, but for some reason kept the mechanical dial where you set cruise altitude and field elevation. All other pressurization information such as cabin altitude, rate of climb and PSI are shown on the MFD, so it's odd that the system wasn't completely automated, but the workload is hard to complain about with only one required setting.
I don't know what to say about the operation of the G1000 system that you haven't read before. I watched it fly a full RNAV approach including procedure turn, glidepath capture and miss to a holding pattern entry. I could look at a Jeppesen chart of the procedure, or a map over topographical colors, or XM Weather and all of the things we have come to expect from current avionics systems. The 850 does not yet have Garmin's synthetic vision technology (SVT) but will as soon as it is approved in Europe and then the United States. It will be a software change to that exciting new safety capability.
