The Safety of Diamond’s Incredible DA62 Diesel Twin Just Blows My Mind

10:05 AM

By Dan Pimentel,
Airplanista Blog Editor

At EAA AirVenture Oshkosh 2018, I was thrilled with Diamond Aircraft’s Aircraft Sales Manager/Demonstration Pilot, Trevor Mustard, agreed to spend a few quality minutes with me and Airplanista inside their insanely cool DA62 Diesel Twin. From the moment I showed up to the Diamond “booth,” Trevor was being pulled in 15 directions at once. It seems their line of aircraft are very, VERY popular with just about everyone at Oshkosh.
Trevor is a 2,500-hour Multi/IFR pilot (Land and Sea), a former Northern British Columbia Bush Pilot, Skydive Pilot, and former Production Test Pilot at Diamond Aircraft. He has 750 hours in Diamond’s DA62 and knows the model well.
He was gracious with his time at Oshkosh, but I did not want to take up too much of that, so we had a quick chat, I shot a few photos, and moved to the background. As I watched him in “Sales Manager” mode, he led a group of aviation students through a presentation of some of the magnificent safety features of this airplane. I had to know more.
So this week, Airplanista virtually “sat down” with Trevor to do a deeper dive into the safety features of the DA62. The interview that follows is presented verbatim. There is a ton of info here, and it is a long read. But if you are interested in the home run Diamond has hit with their DA62, please take the time to read this fully. It is rare we get to pick the brain this extensively of someone with this level of inside knowledge. Enjoy.

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AIRPLANISTA: I think any pilot who has flown single-engine has dreamed about owning a twin. But many light twins get a bad rap for being unsafe when suffering an emergency engine-out situation, especially immediately after takeoff. Tell me the exact procedure when a DA62 loses one engine, how the pilot recovers, and how the airplane performs with only one engine developing power.
TREVOR MUSTARD: It’s true that a twin-engine aircraft presents a whole new set of challenges, especially when you lose an engine. The DA62, however, IS the exception. With the reduced pilot workload offered by the simplicity of the Full Authority Digital Engine Controls (FADEC), the enhanced directional stability provided by the large rudder, the time (and altitude) saved through increased situational awareness on the G1000 display and the ability to secure/feather a disabled engine with one flip of a switch, an emergency recovery procedure can be exercised quickly and concisely. 

The DA62’s Austro engines are also positioned relatively close together. This design reduces the amount of adverse yaw in the event an engine is lost. The procedure any multi-engine pilot is trained to work through in an emergency engine out scenario has always remained the same; IDENTIFY (that there is a problem), VERIFY (there is a failure – dead foot, dead engine/engine instrument scan), then feather the prop, secure the engine, complete your emergency checklist and communicate your situation. These steps do not change with the DA62, and we routinely run an emergency scenario to illustrate the exceptional flight characteristics of the Diamond twins on nearly every demonstration. 

The difference with the 62 is in the reduction of work required to safely secure the engine and remain in positive control. Once an emergency has been identified, then verified, the pilot needs only to select the affected engine’s Master switch to OFF. At that point, the Austro engine will shut down while simultaneously feathering the three-bladed MT prop. The pilot, meanwhile, will have pushed up the power on the good engine, maintained directional control with the rudder, established a positive rate of climb, re-trimmed and completed the emergency checklist. In a demonstration, I typically show a DA62 at 6,000’ ASL with an engine shut down and feathered, trimmed up and flying away, hands and feet off the controls, all while maintaining 450’ per minute in the climb with 4 adults onboard and 50 USG of Jet A in the tanks. I certainly don’t know of another piston twin that does it with such ease. In a dynamic cut scenario (full power, gear down, flaps set T/O), with a failure at Vr, things happen a bit quicker. IDENTIFY, VERIFY, FEATHER PROP still all takes place (in that order) along with coordinated pilot inputs to maintain directional control. Next task: establish a positive rate of climb and get the gear and flaps up to reduce drag. The DA62 will climb out at 200’ per minute (loaded) in this scenario.

AIRPLANISTA: It appears the DA62 is very technologically advanced. Tell me about a few highlights of the safety features that are included in your systems, starting with the avionics.
TREVOR MUSTARD: The DA62’s panel is comprised of the Garmin G1000NXi, which works seamlessly with the GFC 700 autopilot system. The digital standby instrument displays are supported by the SAM unit from Mid Continent. Synthetic Vision Technology (SVT) further enhances a pilot’s awareness through visual queues, and aural call outs. As a single pilot IFR aircraft goes, the DA62 is spectacular in ease of use, safety redundancies and intuitive systems logic.

AIRPLANISTA: I was particularly interested in the safety built into the airframe, especially the seats. What features in this regard make the DA62 safe in the unfortunate event of a crash?
TREVOR MUSTARD: The DA62’s seats are (like all Diamond models) are fixed in position and are tilted slightly aft. This is referred to as an “anti-submarine” design. In a crash scenario, the inertia drives the pilot’s mass into the seat as opposed to allowing it to slide forward towards the instrument panel. Crush blocks under the seats absorb a portion of the energy and reduce the potential for spinal injury.

AIRPLANISTA: Let’s talk about those sweet Austro AE330 engines. Tell me in terms of moving parts and dependability how these diesel engines burning Jet A compare to 180 HP aircraft engines that burn 100LL. Also how do the two engines compare when it comes to maintenance?
TREVOR MUSTARD: The Austro AE330 is a 180hp, turbocharged, 2.0 liter, liquid cooled, reciprocating compression engine burning Jet A. It is based on a Mercedes engine block and is the first engine to successfully incorporate automotive technology into an aircraft. In comparison to a traditional 180hp, air-cooled piston engine, the Austro may seem unconventional. The Austro is larger, heavier and liquid cooled, but out performs the last century’s technology hands down. By having a liquid cooled block, you maintain a much more even thermal heat distribution throughout the engine. No more cool cylinders at the front and hot cylinders in the back. Additionally, the risk of shock cooling a cylinder in a rapid, power-off descent is a thing of the past. 

The electronic engine controls allow for an effortless push-button start, significantly reduced fuel burns and downloadable engine data. In a high utilization flight environment, the ability to “trend monitor” the engine data, combined with the savings realized at the pumps, makes this technology very attractive. Additionally, Jet A is lead-free fuel, available worldwide and generally cheaper (per gallon) than 100LL AVGAS. There are no plugs to foul or magnetos to misfire. This is a compression engine; proven in millions of diesel engines driving on the roads worldwide. Compared to a Continental or Lycoming, the Austro may seem complex, but still follows the same principles as any piston engine: suck, squeeze, bang, blow.

AIRPLANISTA: Describe the “passive safety technology” used in the DA62.
TREVOR MUSTARD: When it comes to safety, positive results are what matter most. Diamond has earned a safety record, backed by real world data, that is second to none. The primary goal when the DA62 was built was to create an aircraft that is a pleasure to fly, yet forgiving and safe, while offering maximum protection in case of an accident. “Passive safety” is a term we use to describe the engineered attributes you don’t necessarily think about that will protect you in the event of the unthinkable. 

Items such as a 26G safety cell providing structural integrity of the cabin under crash loads, effective occupant restraints, impact energy absorption blocks under the seats, unobstructed head strike zones, an anti-submarine seat design and a dual wing spar construction which sandwiches aluminum fuel cells utilizing flexible, stainless steel braided fuel lines. Additionally, the DA62 burns Jet fuel which is much less volatile than 100LL AVGAS, thereby resulting in a much reduced chance of a post-impact fire.

AIRPLANISTA: I know you’ve flown the DA62 a great deal. Talk to me about the "book" fuel burn for both engines versus what you have actually seen on some of the flights you’ve made.
TREVOR MUSTARD: The numbers presented in our Aircraft Flight Manual (AFM) are incredibly accurate and reliable. They do not “over promise” in any shape or form. If I were to show you my default aircraft settings on my Garmin Pilot profile, it would look like this: 10,000’ cruise altitude, 80% cruise power setting, 175 KTAS, burning 15.2 GPH total. Compared against the book, they’re right on the money.

AIRPLANISTA: One of the cool things about this plane is the start-up sequence. Walk us through the start-up sequence for the two AE330s, both a cold morning start and a hot start during a middle of the route fuel stop.
TREVOR MUSTARD: The DA62’s Austro Engines have completely changed the rules for the aviation world. Unlike engines that typically require pre-heating in a hangar, a tented cowl, or with 100’ of extension cord, this engine utilizes glow plugs. Like in any diesel engine, the glow plug is a battery-assisted heating element that pre-heats the air/fuel mixture in the cylinder to a temperature more suitable for combustion. Only if ambient air temperatures dip below -22C, does it become recommended to add an outside heat source. When it comes to “hot starts” I often ask pilots, “When was the last time you hopped back into your car after a fill-up and worried about whether it would start?” It’s no different in the DA62. In fact, if the engines are already hot, there’s no need for the glow plugs to assist. It’s just ENGINE MASTER: ON, (quick scan of the PFD for messages) and STARTER: PUSH. The props are turning in the same amount of time it would take to start your car. We’re not dealing with “traditional” aviation engine technology here any longer. The DA62 is a modern aircraft, built with modern materials, has a modern design and an engine that has been utilized millions of times over in Mercedes automobiles; which we all associate with world-class quality and engineering.

AIRPLANISTA: Talk to us about the single power lever technology. Besides the houses getting smaller when you firewall the throttles, what exactly happens when you push the levers forward on takeoff and then pull them back to a cruise setting.
TREVOR MUSTARD: The procedure surrounding a takeoff in a DA62 won’t seem much different to an experienced twin pilot other than there are four fewer levers to manage. Smooth, continuous application of power, right to the stops, will have you racing down the runway centerline in seconds. Full power is represented as a “percentage of load” on the MFD as opposed to a traditional manifold pressure indication. The Austro engines can develop a 100% load for 5 minutes before they require a reduction to Max Continuous Power (MCP) at 95%. Unless you’re in an environment that necessitates a full power climb, most pilots will comfortably reduce the engine load to MCP after they have cleared 1,000’ AGL. Once you’re established in a cruise climb, the Austros will not need to be adjusted until you have captured your desired altitude. 

In cruise, the Austros will still maintain a MCP setting without overwhelming temperature and pressure settings, but most pilots, like myself, will choose a setting that further compliments the already astonishing fuel burns. 80% load is my preference in the straight and level phase. The workload reduction on the pilot offered by the simplicity of FADEC makes the single pilot IFR world much easier to manage, without question.

AIRPLANISTA: Tell me one safety feature of the DA62 we have not discussed here that Diamond’s engineers are incredibly proud of.
TREVOR MUSTARD: I can’t speak for the engineers first hand, but I’m sure that they must be very proud of the fact that the DA62 is a safe, well-designed airplane that has evolved on the proven success of its predecessors. The simple philosophy of starting with a safety concept and then building an aircraft around it has resulted in one of, if not the safest, general aviation models of all time.

AIRPLANISTA: When I sat in your DA62 demonstrator at #OSH18, because the seat is fixed and the pedals adjust, I am not a big dude, so my arms seemed too short to comfortably reach the panel without the seatback way forward in an uncomfortable position. How does the DA62 rectify this situation when a smaller pilot does not fit it the airplane? Oregon Aero seat cushions?
TREVOR MUSTARD: With a larger, more comfortable cockpit, comes a very short list of “first world problems.” I have had opportunities to fly with pilots as short as 5’in the past, so I am familiar with the scenario. By selecting the electrically adjustable rudder pedals to the full aft position, placing a cushion on the pilot seat, we very easily overcome the issue. The matter of reaching soft keys on the instrument panel can be handled through the well-engineered placement of our Flight Management System (FMS) keypad, conveniently tucked into the center armrest.

(Photos courtesy of Diamond Aircraft)

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