@klincecum @askulte @utaylor @josephp
I was able to achieve this functionality by adding a pdf viewer component to the Drawing Entry attachment slide out and making the filename column linkable on the grid.
Behind the scenes when you click on the filename, I called the DownloadFile function of the Ice.BO.AttachmentSvc REST service passing the xFileRefNum for the method parameter.
After that, all I did was set the base64Src property of the PDF viewer component ID to actionResult.returnObj.
A lot of credit goes to @utaylor . I was able to piece this together from multiple posts he has on this site. This truly is a great community and I appreciate all the input from various experts on this site.