Reliability, Safety & Durability
The Graflight V-8 is unlike any engine previously available for general aviation airplanes. It takes full advantage of the high-tech revolution in European automotive design, bringing advances in reliability, safety and durability to bear on aviation, where historically the marketplace has been resistant to change and innovation.
At Engineered Propulsion Systems, we know it is time for a different approach. Being a pilot is a serious occupation, where life and livelihood depend on the quality of your equipment. It should be the most up to date, the most forward thinking, skillfully engineered, rigorously tested and scientifically proven equipment available. But that is not what the competition offers. The airplane engines that populate general aviation are throwbacks to a different age. They have not advanced or changed, and they are not durable, safe or reliable. Here is where the Graflight V-8 soars above the rest:
Compacted Graphite Iron (CGI) Cylinder Block
The Graflight V-8 engine derives its name from this key component. CGI is an advanced material that offers extraordinary strength and fatigue resistance, allowing CGI blocks to be made lower weight than equivalent strength aluminum blocks. It was first patented by a German scientist in 1965, but in 2008 an American engineer, Dr. Steve Dawson, first wrote about using CGI in modern diesel engine cylinder blocks and heads. EPS CEO Michael Fuchs was among the first to employ CGI in the automotive field in America. It has since set the standard in the industry because its high tensile strength provides extraordinary durability. Aluminum aviation crankcases often crack from fatigue – a common point of failure in GA airplane engines. But the Graflight V-8 block offers incomparable durability, and will be able to serve far longer between maintenance overhauls as a result.
Again, the Graflight V-8 takes advantage of stronger materials in its pistons, employing steel instead of aluminum, which is prone to melting failures. Strong, fatigue-resistant steel allows shorter pistons, reducing overall engine weight. And since steel pistons have almost the same thermal expansion coefficient as the CGI block, engine warm-up damage is minimized. Friction and wear are also reduced compared to aluminum pistons, and cold weather starts are not a problem. Taken together, the CGI block and the steel pistons allow for a target TBO of 3,000 hours, compared with 1,500-2,000 hours for other diesel piston engines.
Cylinder Pressure Monitoring
Each cylinder has a dynamic pressure sensor that feeds data to the Electronic Control Unit (ECU) every time a cylinder fires, allowing dynamic optimization of the fuel injection timing over the highly variable conditions experienced by an aircraft engine. Continuous compression monitoring automatically alerts the pilot long before problems like clogged injectors or leaky valves can become serious safety problems.
Redundant Electronic Control Units (ECU)
The engine performance and propeller control are managed by a dual lane EECS (Electronic Engine Control System) manufactured by Bosch. The EECS is a key component allowing the engine to reduce pilot work load, enhance fuel efficiency, and it allows predictive maintenance which is unheard of in General Aviation. Utilizing Bosch’s vast majority of latest generation chip and processor technology ensures our customers the best and most up-to-date technology on the market. The basic architecture of the EECS consists of two lanes with two independent processors performing redundant calculations backed by an intelligent voter chip. The results of both lanes will be monitored by another voter system that will run in an AUTO mode scenario or Pilot OVERRIDE mode depending on our client’s discretion.
The engine temperature is automatically regulated by the coolant control system. The cooling system operates reliably for both climbs and descents at any altitude or outside air temperature so the Graflight V-8 does not experience the dangerous flame-outs that occur in air-cooled diesels from the excessive cooling of rapid descents.
Electronic Engine Management and Monitoring Systems
The pilot controls the engine with a single power lever. The engine’s ECU controls propeller pitch, engine RPM, fuel mixture and engine temperature. The ECU also monitors all systems for adverse conditions and immediately alerts the pilot of any detected problems. This greatly reduces pilot work-load and increases safety.
Noise, Vibration and Harshness
The Graflight V-8’s proprietary design significantly reduces noise and vibration compared to normal general aviation aircraft. Hartzell independently measured EPS propeller vibrations, finding them the lowest of any diesel engine. EPS has the only aviation diesel engine that can safely drive an aluminum prop.