70th anniversary of the T-28. This is the annual clinic for pilots who fly the T-28. There will be more than the normal number of T-28s practicing at the Sheboygan County Airport (SBM) during this time frame before they go to Airventure in Oshkosh.. The plane is best known locally because it was used during the secret war in Laos. Both Hmong and American pilots flew the T-28s.