Aviation turbine fuels are used by some customers in both the military and civil areas; however warranty claims with regard to achievable performance, dynamic behavior, startability, emissions behavior, service requirements and achievable service life of Mercedes-Benz engines are linked to the use of standardized, good quality diesel fuels, e.g. DIN EN 590. If Mercedes-Benz engines are run on aviation turbine fuels, the operator can expect to encounter some disadvantages.
The disadvantages that can occur with aviation turbine fuel of grades Jet A/A1 and JP 8, JP 5, F 34, F 35, F 44, F 63 (properties, specification: see aviation turbine fuels table) are known to us from rig testing and practical experience with BR 300 and BR 400 engines (commercial vehicle) and the prechamber engines with inline pump in passenger cars. Rig testing of commercial vehicle series 500 and 900 engines are pending. All aspects of newer engines (passenger cars with common rail direct injection) have not yet been able to be evaluated.
The following versions are generally applicable for engines with older technologies (model series 300 and 400 (CV) and the prechamber engines with inline injection pump for passenger cars) and, with some curtailments, for CV model series 500 and 900. Something similar applies with regard to the new fuel F 63, which is formulated from F 35 through addition of wear-protection and ignition improver additives; the extent to which the additives achieve the desired effect is something we cannot yet fully assess.
A major drawback of such fuels for diesel engines is in their non-defined ignition performance (cetane number), which may also assume cetane numbers of less than 40. This, in turn, can result in poor starting characteristics, combined with the development of white exhaust, as well as to a deterioration in emission levels. In order to improve cold start ability, it is advisable to use additional starting assistance (flame starting systems or special heater flanges).
The reduced lubricity (excessive "HFRR value") can cause increased wear in the injection system; the components that are subjected to extreme stress can be expected to have a significantly reduced service life.
The lower distillation fraction can reduce the service life of the injection system as a result of cavitation erosion on nozzles and injection lines.
Due to the lower density, less engine output (approx. 5 %) can be expected. A filter insert that is resistant to aviation turbine fuel must be used as the fuel filter. The filter inserts in passenger car engines and those that in commercial vehicle engines in model series 500 and 900 meet this requirement.
For commercial vehicle engines in the 300 series, filter inserts with a part no. of 000 092 38 05 must be used. Suitable filter inserts for series 400 engines are available on request from the suppliers who cooperate with MB (Hengst, Knecht).
Aviation turbine fuels of grade Jet B, JP 4, F 40 have not been tested by Mercedes-Benz and are not recommended by virtue of the as yet lower boiling characteristics and lower density.
The table overleaf contains the most frequently used qualities, together with the corresponding designations and main requirements.
Table: The specifications in the same list describe approximately identical fuels. They typically differ in respect of three main characteristics: density, boiling range and freezing point. We recommend consulting the comprehensive original standards (ASTM D 1655 or MIL-T-5624 and MIL-T-83133) for more detailed information.