5.1.1.6. During the tests, in the case of a power-driven vehicle authorized to draw a trailer equipped with a compressed-air braking system, the supply line shall be stopped and an energy storage device of 0.5 litre capacity shall be connected to the pneumatic control line - if fitted - (in accordance with paragraph 1.2.2.3. of Part A of Annex 7 to this Regulation). When the brakes are applied for the fifth time, as provided in paragraph 5.1.1.5. above, the energy level supplied to the pneumatic control line shall not be below half the level obtained at a full application starting with the initial energy level. a0c0