\version "2.18.2"
#(ly:expect-warning "no viable initial configuration found: may not find good beam slope")
\score{
  \new PianoStaff <<
    \new Staff = up {
      \relative c' {
        \key des \major
        \time 2/4
        \clef treble
        <<
          {
            f4 es
          }
          \\
          {
            s2
          }
        >>
      }
    }
    \new Staff = down \with{
      \consists "Span_arpeggio_engraver"
    }
    \relative c'{
      \key des \major
      \time 2/4
      \clef bass
      \set Staff.connectArpeggios = ##t
      <<
        {
          aes,16 des \change Staff = up \voiceTwo f aes \change Staff = down
          \voiceOne aes, c \change Staff = up \voiceTwo ges' aes
        }
        \\
        {
          des,,2
        }
      >>
    }
  >>
}