data from multiple servers to output file

I am trying to get data from multiple servers based on a select string and output string data from multiple servers to one file 

  $servers = @("server1","server2","server3")

        $pattern = "(?'min'\d{2}):(?'sec'\d{2})\.(?'hun'\d{2})"

        $tgtDate = (Get-Date).AddDays(-1) | Get-Date -Format yyyyMMdd

       $dstFile = "C:\scripts\test.txt"

        New-Item -ItemType File -Path $dstFile -Force

        foreach ($server in $servers)

        {    

             $tgtFolder = "\\$server\LogFiles\foo_pilot\"

            Write-Verbose "Target date $tgtDate on $server"

            $max = $avg = $totalTime = 0.0

            $min = 100.0 # set this to something greater than the largest time

            $count = 0

            $serverData = Get-Content -Path (Join-Path -Path $tgtFolder -ChildPath "spmanager.log$tgtDate") |

            select-string 'Elapsed time for PICKLIST_SERVICEv10.getFilWorkLoad:' -SimpleMatch

            Out-File   $dstFile 

        }          

the script runs but i am getting only one server data. any help on this.