TMB 900: DAHER Builds A Nearjet

More realistically, however, budget-conscious buyers tend to lean more toward the Embraer Phenom 100 ($4.1M), Cessna Mustang ($3.5M) or Eclipse 550 ($3.2M). The HondaJet 420 is another possibility at about $4.8M, but that may be outside the province of entry-level jet buyers.

For at least the last quarter century, there have been a variety of single-engine turboprops that have offered economical alternatives to the small jets, traveling at near-jet speeds at a lower purchase price and with more economical operating costs.

By far, the fastest of these are the DAHER TBM models known as the 700, 850 and 900. I flew one of the first TBM 700s back in 1991 when I co-hosted the ABC-TV show, ABC's Wide World of Flying, and I've been in love with the type ever since.

Recently, I flew the newest and best of the TBMs, the TBM 900, flying with Danielle Quinn and John Hobkirk of AVEX in Camarillo, Calif. AVEX (www.newavex.com) is the world's largest TBM dealer, and it typically delivers about 10 new TBMs a year, plus another 20 or so pre-owned DAHER turboprops.

AVEX co-founder Terry Winston has been responsible for DAHER sales of the French turboprop in the Southwestern U.S. for the last decade. He arranged for me to fly a new TBM 900 with demo pilot Hobkirk riding shotgun and Quinn along to answer questions about the new model.

The TBM 900 project was initiated shortly after DAHER acquired TBM in 2009. To that end, the new owner canvased existing TBM customers to analyze their wish lists. The preceding TBM 850 was no slouch. It had sold some 180 units in the first four years of production, but DAHER knew it could do better.

As a result, the company initiated a 40-million-Euro program of research and development to improve the TBM line. DAHER used computational fluid dynamics on what was known internally as the "Century" project.

Development of the 900 was undertaken in the strictest secrecy, and hardly anyone outside the Tarbes, France, manufacturer knew of the project. In fact, even Terry Winston of AVEX wasn't aware of the new model until he went to France to inspect the first of his 2014 models.

Externally, the 850 and 900 appear fairly similar, except for the winglets. Take those away, and pilots unfamiliar with the type would be hard-pressed to tell the difference between the 850 and 900, though there are some major improvements. Danielle Quinn and I walked around the airplane during the preflight, and she pointed out the upgrades.

All TBMs, from 1991 to 2015, are precision machines. Quality control is nothing short of excellent. The airplanes levitate behind a chronograph of an engine, the near-legendary Canadian Pratt & Whitney PT6A-66D. The TBM series flies like it should have Breitling instruments and Northrup controls. This dedication to quality and precision carries through to the new TBM 900.

Approach any of the TBM turbine models from the rear, and you can't help but notice the airplane's huge flaps. Collectively, they cover 78% of the wing trailing edge. That's because the French military was one of the launch customers back in 1991, and it insisted the airplane have a stall speed of no more than 53 knots flying light and dirty. That's a phenomenal stall for such a high-performance machine. The only realistic way to comply with that requirement was to install a pair of Fowler flaps that occupied most of the aft trailing edge of both wings.

This didn't leave much room for ailerons, so DAHER added spoilers that would improve roll rate and maintain reasonable control harmony.

The result was a TBM with the widest operating envelope of any airplane with a propeller. Red line is 266 knots and dirty stall is 53 knots, so the TBM 900 enjoys a performance ratio of five to one. "That becomes especially important when we're transitioning new owners out of Mooneys, Bonanzas and Malibus," said Quinn. "Eighty-five knots isn't out of line for the big piston singles, and it also works well for the TBM."

DAHER mounted a pair of the aforementioned two-foot tall blended winglets on the wingtips of the TBM 900, primarily to improve low-speed handling at high angles of attack. The company tried a variety of winglet configurations, but the swept, precisely sculpted shape of the final design complimented the airplane's swept lines. In combination with aerodynamic rethinking of the ailerons, vertical stabilizer and inner gear doors, the net profit is about three knots.

One of the major changes to the new airplane is the standard crew door that allows a pilot to arrange his passengers in back, make certain they're all properly strapped in, then close the aft door and enter the cockpit through his own entrance, rather than having to make his way forward in the aisle. The cabin is 48 inches wide by 47 inches tall, so all but great apes in back should be comfortable, but the crew door makes ingress/egress notably easier. The small, left-front door does add 45 pounds to empty weight and another seal to inflate, but virtually all owners generally love it.

The original TBM 700 was limited to 700 shp for takeoff. Now, the TBM 900 unleashes the full 850 shp of the P&W PT6A-66D turbine, not only for takeoff, but also for climb and cruise as high as FL280. Max thermodynamic horsepower is 1,825 shp flat-rated to 850 shp. Both the 850 and 900 use the same engine, but the 900 benefits from efficiency improvements in both the induction and exhaust system that allow it to use 850 shp under all conditions.

During the power analysis, DAHER's engineers discovered that the exhaust stacks were causing turbulent flow and power loss. The angle on the stacks was too sharp. Accordingly, DAHER rounded the exhaust stack to even the flow. One peripheral benefit was less soot on the side of the airplane.

Under the hood, the starter/generator has been pumped up to 300 amps and the standby alternator has been boosted to 100 amps. Access to the engine is now through a lightweight, carbon-fiber door on the left side.

One curious idiosyncrasy is a small strake mounted on the belly near the left wing root leading edge. Aerodynamic testing revealed turbulent flow at that position, and the strake was installed to smooth the airflow and improve low-speed handling.

Out on the pointy end, the 900 mounts an impressive, five-blade, Hartzell semi-scimitar prop to translate power to thrust. The prop's contour is custom designed for the TBM 900 and features curved, swept blades that are contoured in chord and width. There's not a flat section to be found anywhere on the new prop. "Hartzell owns and operates two TBMs," Quinn explained, "so the project was especially meaningful for them."

Another change is that the prop is mounted with no more than an inch clearance from the air intake. This increases ram pressure, and again, improves power, especially at high altitude.

The TBM 900 uses pneumatic deice boots that actually create the wing leading edge. The real leading edge is flat, mounted about five inches behind the boots. This leaves a cavity between the forward wing and boots for running electrical and pneumatic lines. The boots are overlaid on the wing to form the actual leading edge.

Also, deice boots are installed in three segments on each wing, so that a bird strike or other anomaly won't necessitate removal and replacement of the entire leading edge.

Fuel is characteristically contained in the wings---291.6 gallons (1,954 pounds) in total. At a typical high cruise burn rate of 60 gallons/hour, you could plan easy four-hour legs, five hours at reduced power settings. Under most conditions, fuel management is unnecessary, as the fuel selector will automatically cycle between tanks every five minutes.

Beneath the wings, the TBM benefits from a simplified two-door gear enclosure. The original model 700 had a three-door system, with one door inboard and the other two outboard. This led to an occasional gear-sequencing problem, and DAHER redesigned the system to eliminate the inboard door and still fully enclose the wheels.

Not surprisingly, the new design was more aerodynamically efficient. DAHER estimated the underwing cleanup was worth five knots of additional cruise.

Inside the airplane, the biggest change is the switch to a single, fist-grip power lever. Gone are the prop control and the condition lever present on other turboprops. The prop is now automatically regulated at a constant 2,000 rpm by an on-board computer. The condition lever's function is incorporated into the single control.

A fringe benefit of the single power lever is that the center power console is now narrower, making it easier to climb into the crew seats.

The avionics package remains the popular Garmin G1000, three-screen PFD/MFD, plus the proven G700 autopilot. The demonstrator aircraft also was fitted with Garmin SVT (Synthetic Vision Technology) that introduces Garmin's version of virtual reality. This ignores weather and presents a constant moving image of the terrain ahead, right down to the center stripes on the runway. The refresh rate is about seven times a second, so the image seems almost motion picture quality.

We boarded the demonstrator on a warm day in Camarillo with an IFR flight plan filed for FL280. The load was three souls and full fuel. Some manufacturers shy away from full fuel on press demo flights, as flying lighter always improves the numbers, but AVEX was so confident of the airplane's ability that it had filled the tanks.

Start is fairly automatic in the TBM 900. Starter and igniters turn off at 50%, and the airplane settles into a high idle. Release the brakes, and you'll start to move forward almost immediately. Check pilot Hobkirk suggested I use the prop's beta range for speed control rather than brakes. It's easier on the airplane and minimizes the characteristic, high-pitched scream of a turboprop.

Pre-takeoff checks (door closed, engine running) complete, the TBM 900 is ready to fly. Release the brakes, advance the thrust and the airplane begins to devour asphalt faster than you'd believe. Acceleration comes on like a light switch if you hurry the thrust lever, not a surprise considering that power loading is only 8.7 lbs./hp. You're virtually guaranteed a quick dash to rotation. Point the nose uphill, and the TBM 900 climbs as if something bigger is chasing it.

Lifted off and pointed up, I saw an easy 2,000 fpm initially, though LA Center didn't allow us to ascend directly to our planned altitude of FL280. We step climbed through 4,000, 12,000, 18,000, 23,000 feet and finally topped off at FL280. DAHER suggests the airplane can manage a direct climb to FL280 in 16 minutes, and in view of our uphill performance at lower altitude, I believe it.

Leveling at cruise, we watched the TAS readout on the G1000 count up through 315 knots, then slowly increase to a final 320 knots. To no one's surprise, in the middle of a Southern California summer, outside air temperature at altitude was ISA +10 degrees C. Correcting for the warm conditions, the TBM 900 would have been managing 331 knots.

All the new TBMs are RVSM certified, and if we'd bothered to climb to the airplane's max certified altitude of FL310, we would have seen 326 knots at a reduced fuel burn. Long-range cruise is just greater than 250 knots at 31,000 feet, burning 45 gph.

Pressurization is automatic on the TBM 900, and the 6.2 psi differential allows a sea-level cabin at 14,500 feet. Climb on up to 31,000 feet, and the cabin will level to just less than 10,000 feet.

If the stage length is a long one, you can plan on ranging as far as 1,730 nm (NBAA reserve) in the TBM 900. Virtually any of the jets will need a stop.

Once we had our cruise numbers on tape, we dropped down to 16,000 feet for some slow-speed maneuvering and stall checks. Stalls haven't changed on the 900. The onset of stall is easily predictable with plenty of aerodynamic burble. Hold the yoke full back at the break, and the airplane will pitch straight ahead, with little tendency to drop a wing. The airplane is basically as stable as a table and happiest in straight and level, high-speed cruise.

Back in the pattern to check landing manners, there are, once again, no surprises. If you're sneaking into a 3,000-foot strip, you can approach at 90 knots or less without concern. The TBM 900 doesn't tend to float in the flare, and it's easy to gauge your height above the runway. Should you need to plunk it on and stop it short, full reverse and hard braking will ground the TBM 900 in 1,500 feet or less. Remember, however, not to maintain reverse thrust below about 30 knots on turf or dirt runways, or you could blow debris out ahead of the airplane and suck it back into the intake. Pratt & Whitney's inertial separator guards against engine damage, but as with any turbine, the best rule is "don't" if you have any doubts.

Inevitably, any value analysis of the TBM 900 devolves to price. A fully equipped DAHER TBM 900 runs about $3.8M, roughly the same as a Cessna Mustang and slightly more than an Eclipse 550. Pretty obviously, both of those jets are 10 to 30 knots faster than the TBM 900, but neither have the TBM's range. The Mustang and Eclipse also are certified for flight at FL410. Conversely, both the jets must support two engines rather than one.

Such buying decisions rely as much on emotion as logic. Personally, I'd love to buy a jet with my next big lotto win, but the almost mythical reliability of that beautiful Pratt & Whitney engine and the striking asymmetry of the five-blade prop would probably answer all the questions for me.

By Bill Cox

One of the TBM 900's most impressive talents is its ability to outperform virtually every other turboprop on the market, do it with better economy and even keep up with some light jets in cruise.

George Schaeffer of Schaeffer Industries in California is one example of a TBM 900 owner who uses his airplane to maximum advantage. Schaeffer operates a series of steel processing facilities in Linden, Utah, and Mira Loma and Stockton, Calif. His company services clients all along the West Coast, and Schaffer is a hands-on kind of owner. "This is my second TBM. I traded a TBM 850 for this airplane and flew a Mooney Bravo before that."

Schaeffer was building an Epic until that company went bankrupt "and things got pretty murky," he said. "I looked at both the Eclipse and the Phenom, but both cabins were too small for my needs."

Schaeffer picked up his new TBM in November 2014 and flies at least three times a week on legs of 300 to 800 nm. "It's a nearly perfect tool for my travel needs," said Schaeffer. "I'm usually flying fairly light, so I consistently see climb that's better than book."

The steel executive usually flies as high as possible, sometimes at the airplane's maximum altitude of FL310, "though I'd love to see TBM extend that to FL340," he commented. "There've been several instances when I was just barely clipping the tops of the clouds at 31,000 feet, and another 2,000 to 3,000 feet would have been ideal."

Schaffer feels the TBM 900 is an excellent combination of speed, comfort and efficiency. "I generally see about 320 to 325 knots on 55 to 60 gph, and I've witnessed the promised 330 knots several times. Most every number in the POH is realistic. If it's in the book, the TBM will do it."

The owner bought both his TBMs from AVEX in Camarillo, Calif., and he credits AVEX owner Terry Winston as an outstanding dealer. "If TBM comes out with a model 1000, Terry can probably plan to see me again."

For more information, visit www.newavex.com.