When Diamond introduced an unlikely light twin nearly 15 years ago—diesel powered, no less—it seemed like a long shot. Yet the DA42 found surprising traction in a market no one knew was starved for economical trainers. With its new DA62 twin now flying the demo circuit, Diamond isn’t expecting to repeat the trick in sheer sales numbers, thanks to a princely price and buyers far scarcer than they were a decade ago.
But even at over a million a copy, the DA62 is already attracting enough business to make it a market presence rivaling Piper’s Seneca and Seminole and Beechcraft/Textron’s G58 Baron, which shares a similar north-of-$1.0-million price tag. While in its sales salad days, the DA42 sold as many as 160 units a year. After the bottom dropped out of the economy in 2008, Diamond moved a couple of dozen twins a year to a combination of schools and private owners. It ran into a rough spot with the then-Thielert diesels in 2007, but eventually recovered with improved motors.
Given its luxury panache, the DA62 seems more likely to become the personal ride for owners wealthy enough to afford it. And given that it is, in our view, the most sophisticated airplane Diamond has ever offered, we think those buyers aren’t likely to be disappointed.
Aerial SUV
When we first encountered the DA62 as a test article in 2013, its designator was the DA52, but only the name has changed. The basic airframe is a stretched version of the DA42 twin and, in fact, the DA62 resides on its progenitor’s type certificate. At the time, Diamond CEO Christian Dries said he viewed the new twin as an
SUV or a minivan. It’s certainly big enough for that. Up close, it stands higher than the original DA42 and it’s two feet longer. It reminds us a bit of an Aztec, if an Aztec could be sculpted in carbon fiber.
The wingspan increases from 44.5 feet to 47.8 feet and the tips are upswept. The top of the tail is a full foot higher than the DA42. For as noticeable as these changes are from the outside the airplane, the cabin interior is markedly larger in both width and length, thanks to a 5-inch plug inserted longitudinally between the two fuselage halves. Ostensibly, this makes the DA62 a seven-seat airplane, with two up front, three in a wide bench seat that serves as a mid-row and two kiddie seats in the rear. But practically, it’s a four-seater with prodigious baggage capacity or a five-seater with moderate range and surplus payload.
Where the original DA42 shared the forward-hinged bubble canopy introduced on the DA40 single, the DA62 has a pair of gullwing doors that hinge up out of the way for ingress and egress. For access to the rear, Diamond enlarged the left-side hatch to barn-door proportions and supports it with a spring mechanism to make it easy to open and close. Entering involves simply stepping down into the cabin from the wing.
The rear-most seats, which are a $27,725 option, have more room than they appear to, but in our view, they shouldn’t be considered adult accommodations. For one thing, they’re tight for large people and for another, the airplane doesn’t have the practical payload for seats-full flying.
Payload, Ergos
At 5071 pounds max gross, the DA62 is the largest, heaviest airplane Diamond has ever built and it doesn’t lack for useful load. The example we flew had a useful load of about 1600 pounds. With 86 gallons of Jet A aboard, that translates to 1000 pounds of payload. That would accommodate seven if two of the passengers are kids weighing 75 pounds or so. More realistically, the DA62 is a four- or five-place airplane with all but unlimited baggage space. For example, with four aboard—even a heavy four—there’s still payload for 200 pounds of baggage.
Because of European ATC regulatory limitations, there are two versions of the DA62 and the European version is limited to 4397 pounds, a whopping 674 pounds less than the North American version. That’s more than the weight of the full fuel load and turns the airplane into a two- or threeplacer with full fuel. Be glad you don’t live in Europe. Speaking of fuel, the airplane has a 4850-pound zero fuel limit. So on an empty weight of 3471 pounds, 1379 pounds can go in the cabin, but the remaining 221 pounds must be fuel. That’s about 32 gallons.
Diamond’s Brent Eddington, one of the company’s tour pilots and its sales manager, told us that initial buyers seem to be skipping the rear seat option in favor of more baggage capacity. And can the mid-seat really accommodate three people? Yes, but not three wide people or should we say largish people better be warm friends. But for four people aboard, the mid-seat is positively capacious by any standards.
So are the cabin appointments and comforts. The airplane has air conditioning as an option ($34,686) and we appreciated that on a warm Florida day. The seats are richly appointed in leather and at every turn, the detailing, fit and finish are what you’d expect of an airplane with a typically equipped price of $1.3 million on a base of $1.08 million. Diamond isn’t new to this composite thing and a white-glove inspection of the paint, door fit and laplines will reveal unblemished perfection.
Inside, the front seats are equipped with a spring-loaded extension that gives enough room to squeeze past the stick, but effortlessly flips down to provide support for the lower legs. The seats don’t adjust longitudinally, but the rudder pedals do—electrically with a small button on the lower left side of the panel. You want cup holders? Of course you do and Diamond has integrated those, plus water bottle holders on the cabin forward sidewalls. Thankfully, Diamond didn’t use the sidewalls as a place to mount circuit breakers you can’t get to. Instead, they’re mounted on the right-side panel in place of a third Garmin screen that you don’t really need anyway.
The panel has come a long way from the first DA42. For one thing, it’s wider, so there’s more room to spread things out rationally. The early DA42 had engine monitoring instruments that we would generously describe as retro—start-of-the-art digital. In the DA62, and in all of the Austro-engined twins, engine monitoring is integrated into the G1000. Furthermore, in the DA62, Diamond has redesigned the engine start/check switches to be more consistent with the airplane’s high price. The demo airplane had TKS de-icing ($89,485) with the control panel for that located above the engine switches.
As does every Diamond airplane, the DA62 has center sticks and we’re unapologetic in saying these are superior to side sticks or side controllers or whatever you want to call a control that isn’t where it should be. The human anatomy is such that with a side controller, movement to the left is weaker than movement to the right or toward the body. A center stick has no such limitations, thus finer control input is possible without fatigue. The tradeoff is that the stick gets in the way during ingress and could be an encumbrance in a crash. Overall, we think the tradeoff is worth it.
Diamond has the throttles readily to hand on a center console, with rudder trim at the top of the stack, along with the parking brake and cabin heat controls. The fuel controls—on, off, crossfeed—live at the aft-most end of the console. There’s also a big honking manual trim wheel on the console right where you want it.
We’re all for electric trim and all, but increasingly, as a weight-saving measure, airplanes have electric trim as the only option But manual trim is both faster and more precise. It’s nice to have the option of both. Jacks for the headsets are also at the back of the console, under an armrest that pivots out of the way to provide access.
Here a word about the engines. They are the latest iteration of the Austro 300 series, the AE 330. By tweaking the EECU—no mechanical changes—Austro is wringing 180 HP out of these 2.0-liter, four-cylinder powerplants based originally on the Mercedes Benz OM640, an engine the carmaker has manufactured by the millions. In the AE 330 form, the engine is turbocharged with a common-rail injection system, electronic injection and a single-lever power control with auto-feather capability.
As do the Thielert/Continental diesel engines, the AE 330s have reduction gearboxes, but unlike the Continental models, the Austro gearboxes don’t require interim overhauls. They go the length of TBO and here a shortcoming: The TBO is currently 1000 hours, rather short for an airplane costing this much. Diamond pledges to increase this as regulators review the operating data, but worth noting is that none of the diesels currently flying in volume have the 2000- or 2400-hour TBOs that Lycoming and Continental gasoline engines do. Austro engines, by the way, are overhauled, not replaced as are the Continental diesels. Taking the sting off the stingy TBO is a reasonable overhaul price of about $25,000.
Flight Trial
Like previous Diamond twins, the DA62 is complex electrically, but simple mechanically. The electronic complexity is mostly opaque to the pilot and involves integration of the engines with the avionics. Other than the engines, mechanically, the airplane is manual operation. The flaps are electric and the gear is electromechanical, with a power pack in the nose compartment. The fuel system is simple. The left side feeds the left, the right side the right and crossfeed is available. Total capacity is 86 gallons, with 50 gallons in two 25-gallon mains and 36 gallons in two 18-gallon nacelle auxiliaries. In our view, Diamond leads the industry in protecting fuel against post-crash impact. The fuel resides in aluminum cells connected by armored lines and protected between two heavy spar elements. As a result, Diamond’s incidence of post-crash fire—even in the gasoline models—is among the lowest in the industry.
Because of its simplicity to the pilot, the preflight checklist is short for an airplane of this class. Engine start involves flipping on the engine masters and pushing one of the silver start buttons. This is a bit unnerving. The engines are so quiet and so smooth, it’s not easy to tell when they’re running and when they’re not. The Austros are, by far, the smoothest engines we’ve encountered.
Runup is automated. Each engine has a dual-channel electronic engine control unit (EECU) with switches on the panel to verify each channel. A pair of momentary buttons held for about 30 seconds will run full checks on the engines, automatically increasing the RPM when necessary to check the feathering and ECU performance. Once the engines return to idle, the buttons are released and the runup is done. If there are no faults on the G1000, the airplane is ready to fly.
But first, you have to taxi it. Here, another minor ding. The nosewheel bears a lot of weight and we found the pedals to be unpleasantly stiff, demanding stabs of brake where we otherwise might not want it. But there’s a workaround and a good one. The engines are throttle by wire and the power levers are silky smooth. That makes steering with asymmetrical power the best way to drive the DA62 around on the ground. It’s actually kind of fun.
Takeoff rotation comes at 75 knots after good but not stunning acceleration. The airplane gathers itself a bit and after gear retraction, it settles into an easy 1200 to 1500 FPM rate. Advertised is 1650 FPM, but the nose—which is quite long as should be evident in the photos—obscures the forward view at that rate.
Diamond airplanes are noted for their balanced, no-surprises handling and the DA62 continues that tradition. Like most light twins, the airplane has some inertia in roll initiation and on final approach, you can feel a hint of PIO if you don’t anticipate it. When disturbed in pitch, it barely has a phugoid at all, recovering to the trimmed airspeed in a cycle and a half. Disturb it a lot and the autopilot’s envelope protection kicks in. That’s true of roll limits, too.
Stalls are rather startling for a twin in that holding the stick full aft provokes no break, wobble or yaw, but a buffeting parachute mode that takes little effort to maintain in a stable state. We didn’t attempt to aggravate or provoke it into a spin. VGs on the wings ahead of the ailerons keep the flow stuck to the wing, making roll control possible into the buffet.
When we flew the test aircraft three years ago, it was an honest 200-knot airplane and the finished DA62 retains that performance. The POH gives max cruise at 201 knots at 14,000 feet, but the reality is a more sedate 175 to 180 knots on about 7.1 to 7.5 per side. With full fuel, that translates to five hours of endurance, with a 45-minute reserve and a still-air range of 875 miles. Back the engines down to 60 percent power and the fuel flow drops to 11.8 GPH and range increases to just over 1000 miles at about 160 knots. The DA62 will do that with four or five people aboard and more than 100 pounds of bags. Baggage can go in the rear or in two nose compartments large enough to accommodate golf clubs.
Traditionally, people fly light twins because they want the safety of the second engine. But that comes with the challenge of handling an engine out. Light twins and really twins other than turboprops haven’t proven to be stellar performers when one engine tanks. More than one twin has crashed because the pilot misidentified the failed engine or otherwise muffed the engine-out drill.
That should never happen in the DA62. The engines are equipped with auto-feathering and although the DA62 has a critical engine (the left), engine-out drills are stupid easy. Shut off the engine master and the rest is automatic. Bring it back by turning on the master and tapping the starter button. (There’s a two-minute limit on flying with one shut down.) Without much drama, we coaxed a 450 FPM climb on a single engine at 6000 feet.
The Austro Idea at a Glance
On a visit to the Austro engine factory in Weiner Neustadt, Austria four years ago, Christian Dries placed his hand on the valve cover of an AE 300 engine and stated flatly: “Mercedes Benz; you can’t do any better than this.”
It was a not-so-veiled barb hurled at his main competitor, the then-Thielert Aircraft Engine company that has since been bought by Continental. Although both the Continental and Austro engines share the same industrial DNA, Austro’s approach is very different than that pursued by Thielert for the development of what became the Centurion diesel and now the CD 135/155.
The original Thielert engine was based on the Mercedes Benz OM668, a state-of-the-art turbocharged four-cylinder engine. But Thielert made substantial changes to the engine, including lightening it with an aluminum block, changes in the cylinder head, a clutch-equipped gearbox and a redesigned ECU.
Austro followed an entirely different path. Although the OM640 it uses as the base engine is similar, Austro retains the core Mercedes engine and adds its own accessories. In fact, fully assembled OM640s are shipped from a Mercedes engine plant to Austro where the automotive parts are stripped off and—gulp—crushed. Austro then bolts on its aviation-specific components, including a gearbox, torsional damper, turbocharger, harness, EECU and a different oil sump.
Because it retains the original cast-iron core, the AE 300 engines are heavier than the Continental models: 408 pounds versus 245 pounds. But in exchange for that structure, Austro teases more power out of the engines and they can be overhauled rather than replaced, as is required with the Continental engines. Furthermore, the Austro engines don’t have the 600-hour gearbox replacement required of the Continental engines. Dries maintains this results in lower overall operating costs and less maintenance downtime.
Conclusion
When we flew the DA42 for the first time in 2005, we deemed it as refined. The DA62 is the same, only more so. The engines are smoother, quieter and more powerful and remain among the most economical piston powerplants in general aviation. Diamond deserves credit for engineering in good passive safety through both handling characteristics and crashworthiness. The company’s extraordinary safety record bears out this effort. The DA62 is but an evolution in Diamond’s design philosophy that improves performance, capability and comfort, albeit at a price that’s hardly for the masses.
If we had any complaints about the DA62, it would be the short TBO. In an airplane this expensive, those engines ought to last longer. We’ll see if operating experience justifies longer TBOs. In the meantime, we’re sure that for owners who can afford one—the lucky 25 to 35 a year—accumulating that first 1000 hours will be enjoyable indeed.
