I tried everything but it doesnt work. It works fine for all other kills like PVP or PVE like scientists or animals

      {
        "KillerType": "*",
        "VictimType": "Helicopter",
        "DamageType": "*",
        "Messages": [
          "{killer} shot the {victim} down with their {weapon} {attachments} over a distance of {distance}."
        ]
      },
      {
        "KillerType": "Player",
        "VictimType": "Helicopter",
        "DamageType": "*",
        "Messages": [
          "{killer} shot the {victim} down with their {weapon} {attachments} over a distance of {distance}."
        ]
      },
      {
        "KillerType": "Player",
        "VictimType": "Helicopter",
        "DamageType": "Bullet",
        "Messages": [
          "{killer} shot the {victim} down with their {weapon} {attachments} over a distance of {distance}."
        ]
      },​

Helicopter death info is currently quite limited, which is why the default message doesn't include any further information either.