AEGPL was invited to present its document (see GFV-31-2) on major pending issues: dual-fuel types (possible exclusion of Type 3), non-compliant diesel engine and engine family definition and durability.

AEGPL proposes to have one common Type B dual-fuel engine, with no distinction in relation to Gas Energy Ratio (GER).

Other experts propose to exclude GER less than 10% in order to prevent possible loopholes in the certification of the engines. The manufacturer may choose to homologate its system as Type 3 (equivalent to diesel), while in-use the system could work with a much higher GER. No definitive decision is taken on this issue.

Regarding non-compliant diesel engines, AEGPL stresses the practical necessity to set a less stringent engine family definition if non-compliant diesel engines are required to meet emission limits in the D-F mode, in order to ease the manufacturer having to search for complaint (or quasi compliant) parent engines to convert.

Mr Dekker confirmed that compliance with emission limits will be required, also in case of originally non-compliant diesel engines.

Mr Renaudin proposed to adopt the R49 engine family definition to ensure that the
retrofit system performs well on any engine models.

AEGPL pointed out that the combination of these two approaches would make the new regulation practically inapplicable as the engine performances in diesel mode impact heavily on the D-F mode.

Regarding durability, the group agreed on the following approach:

• Emission tests have to be carried out with emission-related gas components deteriorated in accordance with R 67 or R 110 endurance test and, in addition, DF have to be applied;
• D-F may be adapted in counter-proportion with the actual mileage of the parent engine since it is an old engine.

AEGPL, although agreeing with these principles, noted that D-F already includes deterioration of emission-related gas components and, thus, the use of deteriorated components during the tests and the contemporary application of D-F would add an additional burden for retrofit systems in respect to R 49 provisions.