On the conversion of automotive engines for general aviation

Automotive engines have outstanding quality controls and extremely high cost-effectiveness. This is typical to lean, mass production. For this reason, the application of these engines on aircraft is most appealing. Ultralight-sport aircraft have pioneered this approach. A few automotive-aircraft certified engines are already available on the market. However, this approach has not been as successful as foresaw a few years ago. This is due to the differences between the automotive application and the aircraft use. These differences have lead to teething problems that have been solved in almost 20 years of research work. The level now reached and the experience achieved makes it possible to convert any "successful" automotive engine into an aircraft engine. This work starts with the description of the data available from automotive manufacturers. Automotive engines have a huge background of statistical data on performance, reliability and TBO (Time between Overhaul). The correlation of these data to an aircraft application is not straightforward. Then the performance curves obtainable from the new aircraft engine are introduced. Finally, an algorithm calculates the residual life to TBO (Time between Overhaul) of an automotive engine. The method was tested on a few small last-generation CRDIDs (Common Rail Direct Injection Diesels) and spark ignition (gasoline) engines. These engines were also converted for use into small aircrafts with power ranging from 60 to 200HP. This very simple method is implemented directly in the FADEC (Full Authority Digital Electronic Control) or E-ECU (Engine Electronic Control Unit) of the engine with very few lines of C-Code (C-Language Code). It is assumed that the engine undergoes regular maintenance schedule and OBD (On Board Diagnostic) is implemented. OBD is perfectly able to foresee the imminent failure of the accessories like the starting motor, the generator, the turbocharger, the injector(s), the HPP (High Pressure Pump), etc. These parts are external to the engine and can be changed during field maintenance. Accidents, like prolonged under/overcooling, crankshaft damper failure, overspeed are monitored by the OBD and require specific maintenance actions. Ordinary problems like excessive fuel, lubricant, coolant consumption, pressures out of range... are also dealt by the OBD-related service system.