Pilot Report: TBM 850

 - July 7, 2008, 11:25 AM

There were more than a few moments during my three-and-a-half hours flying the Socata TBM 850 when it was easy to imagine the conversation I’d soon have with a couple of friends who own piston twins. The TBM is a suitable replacement for their aircraft–a Cessna 421 and a B55 Baron. Although both aircraft are GPS equipped, neither can take full advantage of new technology as sophisticated as the Garmin G1000 avionics system that comes standard on the TBM. The Socata is also certified for flight into known icing using inflatable boots on the leading edge of the wings and the horizontal stabilizer.

The TBM will carry almost the same loads as either of the older airframes but at 100 knots faster. Maximum speed of the TBM is 320 knots. The PT6-powered TBM 850 is surely the fastest new single-engine aircraft sold in the world that can be flown by a pilot with a private pilot certificate. Capitalizing on the fascination with VLJs, Socata is calling its TBM the very fast turboprop (VFT).

Although the big Pratt & Whitney Canada engine–flat rated to 850 shp from 1,825 shp thermodynamic for the TBM–burns more fuel than either of the two piston aircraft, there is only one powerplant to maintain. The reliability of the PT6 is well known after tens of millions of flight hours over the past 30 years, and its overhaul life is set at 3,600 hours. The TBM offers excellent short-field performance, especially on landing, thanks to the reversible pitch of the 90-inch Hartzell propeller.

The TBM 850 has a price tag of $2.9 million a copy, making it more expensive than the Cessna Citation Mustang very light jet, which sells for roughly $2.7 million. The twinjet Mustang is about 20 knots faster than the TBM. The single-turboprop Pilatus PC-12 sells for $3.9 million.

A Beechcraft King Air C90 turboprop twin will run about $3.2 million, and although it offers a larger cabin it is much slower than the TBM. The Piper Meridian, another popular single-engine turboprop, sells for approximately $2 million. It has
a smaller cabin than either the Pilatus or the TBM and, at 260 knots, is the slowest of the three. The Meridian will fly about 1,000 nm with full fuel compared to the TBM’s range of 1,450 nm when filled to its 1,960-pound fuel capacity. The PC-12 will fly about 100 nm farther than the TBM.

The TBM 850 is the most recent version of the well known French-built turboprop–the TBM 700–that appeared in 1992 and initially won favor with the French military. In 1999 Socata certified the 700B with a larger rear entry door to improve loading of large cargo. An optional oxygen system accessed through quick-donning EROS masks raises the service ceiling to the standard 31,000 feet of the 850.

For a single-engine aircraft, the TBM is heavy, weighing in at 7,394 pounds, nearly 2,500 pounds more than the Piper Meridian, but still 3,000 pounds lighter than the larger Pilatus PC-12. The TBM does not offer a permanent lavatory, but owners can opt for a portable unit on long trips. The TBM can be equipped with a separate pilot door, but few owners seem to take this option since it adds about 75 pounds to the airplane.

Simple Operation

Socata demonstration pilot Wayman Luy and I departed from the Boca Raton airport (BCT) one Sunday before EBACE. With only 31.2 hours on the Hobbs, N851GC barely had the dust blown off before our trip. The aircraft was scheduled to depart Muncie, Ind., for a transatlantic trip back to the factory to make it shine like new at the upcoming EBACE show in Geneva. We flight planned for three hours and one minute.

Before engine start, Luy explained some of the TBM components, such as the automatic fuel balance system, which changes the fuel selector every 90 seconds on the ground and every 10 minutes in the air. Most people will never notice that the actual selector is motorized and turns back and forth during the flight. The torque limiter on the TBM 850 restricts power to 700 shp during takeoff. The POH says the limiter may be disengaged after climbing through 1,500 feet agl by pulling the flap switch up and through a detent to use all 850 shp. The flap settings are simple and can be activated at 178 kias. The takeoff setting uses about 15 degrees of flap, while the landing setting uses about 30. The flap lever cannot be placed in both a takeoff/landing position and release the torque limiter for safety reasons.

Pressurization is simple to set by adding 1,000 feet to the flight-planned altitude. The capabilities of the air conditioner on the 850 are much improved over the 700’s unit. The earlier version was 14,000 BTU, while the 850’s unit is 24,000 BTU. The starter generator on the 850 is 200 amps, while the standby unit is 70 amps. At startup, the PFD lights up in the backup mode to display the engine instruments. Fuel quantities are shown in U.S. gallons. Also, when the pilot hits the fuel pump, there is no fuel pressure indication in the reversionary mode on the PFD. The TBM’s backup attitude indicator is suction driven, so there is no backup battery to consider. Initiating a de-ice sequence inflates the outer two panels first, followed by the inner panels and the tail. The aircraft uses two essential electrical busses as backups to each other.

Once the start switch was engaged, we looked for 13 to 15 percent Ng, at which point the fuel lever is brought out of cutoff. Once the engine spins through the green arc on the Ng gauge, the starter is disengaged. The condition lever then goes to high idle. There is a one-minute start limit on the starter.

The empty weight of our aircraft was 4,720 pounds. With three people aboard, the basic operating weight of the airplane increased to 5,120 pounds; the equipment on board brought the total to 5,160 pounds. The flight included 1,910 pounds of fuel, for a total aircraft weight of 7,070 pounds, 324 pounds short of mtow. Our planned route took us north toward Orlando, on to Craig and then direct to Muncie. The Garmin 1000 system made adding and tracking the specifics of our flight plan rather easy.

At brake release on the ramp, I did not need to add any power to the get the aircraft moving. The prop spins pretty far forward of the pilots, so taxiing can seem like a bit of a waddle the first few times. The movement of my feet slowed slightly once I had taxied for a few minutes, but too much movement would certainly be felt in the back seats. The best way to taxi is with the power lever slightly in reverse to keep the speed down.

A Speedy Flight

The initial climb out of BCT called for an altitude stop at 3,000 feet. The tower cleared us for takeoff on Runway 5. The numbers we’d looked at said I should plan just under 3,000 feet for takeoff with an outside air temperature of nearly 80 degrees F. As I pushed the power lever forward at lineup and adjusted it for takeoff torque, that long nose began to zigzag a bit until I settled on the right amount of rudder action to keep the nose headed straight down the runway. The TBM accelerated quickly, and at 85 knots I rotated for takeoff. We were airborne through 50 feet when we passed the tower, indicating a roll of about 2,800 feet. Takeoff power showed a fuel flow of 540 pph.

Luy said the best target speed would be 170 knots, and altitude restrictions disappeared before we reached them so the aircraft was able to streak to high altitude. The flat-rated PT6 allows the pilot to maintain full power at ISA temperatures right up to FL260 with the prop turning at 2000 rpm. Pilots used to hydraulic supported controls might find the TBM a bit stiff, but not so much that it is uncomfortable. Piston pilots not used to turbine powerplants will need to adjust to the constant monitoring of the power lever so as not to over-torque or over-temp the engine during the climb. The maximum torque we would be able to use this particular day was 108 percent during the climb.

As we headed northwest from BCT, we easily saw 1,800-fpm climb rate initially. Out of FL230, we saw an IAS of 140 knots and a true airspeed of 209 knots and a rate that had slipped to 1,100 fpm. ATC did stop us at FL230 during the climb, where we were burning 408 pph with about 15 knots of headwind. Eventually we were able to climb once again and saw 1,000 fpm up to our final cruise altitude of FL270. Including the short delays en route, it took about 15 to 16 minutes to climb to cruise. After a few minutes to accelerate, our numbers this day turned out to be 303 ktas burning 402 pph with an outside air temperature of -31 degrees C. I pulled the prop back to 1900 rpm, which reduced the fuel burn by about seven pph. The airspeed settled on 190 kias. We would eventually see the fuel flow drop to 388 pph during the second and third hour in the air.

Forty miles west of BCT, ATC cleared us direct to Muncie. In level flight I turned on the GFC 700 autopilot, which is mated to the Garmin 1000, to investigate the avionics more closely, including the weather radar. The two 10.4-inch screens are mounted on either side of a larger 15-inch center display that handles most of the details.

There is little doubt that the G1000 offers increased situational awareness, with flight details displayed in places that makes the information easy to read and understand. However, learning how best to use the flight planning, navigation, traffic and terrain awareness features is no small challenge. But the work is worth the effort. The WAAS approach capability alone could make the system more than pay for itself by opening up airports to precision guidance where once there might have been nothing more than an NDB.

This particular TBM was not equipped with XM satellite weather as an option, but the Garmin weather radar did get a workout as we approached the Georgia-Tennessee state line and a line of thunderstorms. While I steered around them with only minor heading changes, Luy and I were able to see a perfect example of the 3-D elements of the storm as we flew over the tops of some weather at FL270.

Visibility out the cockpit windows is good for an aircraft of this size. The cabin was filled with overwater gear and some large cargo items for the flight to France, so there was no way to move around or sit in back to get an impression of the sound level. If the noise level in the front is any indicator, however, all passengers will want to buy and use noise-canceling headsets while flying the TBM.

A Smooth Approach

Dodging the weather consumed more time than I realized, and soon we were only 150 nm out from Muncie. The weather was expected to be good, but I still planned to shoot a coupled WAAS-enabled GPS approach to Runway 32. With a northwest wind, low clouds would normally have called for a circling approach off the Runway 14 ILS. The LPV approach gives you an extra 100 feet of possible descent, without circling while adding an electronic glidepath indicator. The glidepath simplifies the approach by also eliminating the step-down fixes of previous procedures.

Pulling the prop back to idle allows the TBM to descend pretty quickly. I saw a comfortable 3,000 fpm as we aimed ourselves for wambo, the IAF for the Runway 32 approach. For some odd reason, despite being set up properly at 2,900 feet before the glide-slope at cituk, the autopilot did not capture. I had also purposely kept the speed up to see how easily the aircraft might slow on final. Now I was high and fast.

The weather at Muncie was severe clear, so once we realized we’d missed the slope, I pulled the power back to idle. The TBM’s high gear speed of 178 knots slowed us quickly, as did the application of first approach and then landing flaps. We were still high but descending nicely. If this had been actual IFR though, I would have missed the approach to try again. Coming through 500 feet I brought in some power and the approach stabilized. With the TBM’s slight negative deck angle, the view out the windshield takes a bit of getting used to.

If I had a complaint about the TBM, it was a minor one, especially if I were transitioning from a piston twin. Either the TBM’s gear is very stiff, or my technique needs considerable improvement because my arrival in MIE was no better than a firm kathunk. Other TBM pilots said the same about their arrivals. The TBM has been fatigue tested to nearly 137,000 landings.

Pulling the Hartzell into beta after touchdown slows the TBM quickly enough that I needed to add power to make the turnoff on Runway 32. I estimated that we were down and under control in 2,500 feet. We burned about 200 gallons of fuel during the flight, and our flight-planned time was pretty accurate; the flight lasted three hours and two minutes.

The TBM is a clear alternative to a pre-owned piston twin and the few high-performance piston singles left on the market. Certainly the price differential is
vast, but the speed improvements could be difficult to ignore.

To date, 103 TBM 850s have been delivered in the U.S., and 21 of those were equipped with the Garmin G1000. TBM 850 production for much of next year is already spoken for. Buy one today and you could have it in your hangar by next summer.