instead of looking for string index in an array, why not use ints for both. In your code, you could reference constants like StatusType.OPEN etc... then your code could look like:
var sort:Sort = new Sort();
sort.fields = [new SortField("status", true, true), new SortField("help_id", true, true)];
myHelp.sort = sort;
myHelp.refresh();
This would sort by status then help_id at the same time. Then when you need to display the status to a user in GUI, convert the int to a String human readable value