Hola,
Utiliza la API ShellExecute. Sería de la siguiente forma:
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long
Const SW_SHOWNORMAL = 1
Dim Parameters AS String
Parameters = "nombre_archivo.dat.6"
ShellExecute Me.hwnd, "Open", "c:\Datos\Hidraulica\hidra2.exe ", Parameters, "C:\", SW_SHOWNORMAL
Saludos.