What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On 02/07/2013, aircraft N812SK was being repositioned from the terminal to overnight parking when the tow bar disconnected from the aircraft resulting in substantial aircraft damage caused by the tow unit. There were no pax on board, and there were no injuries to ground personnel. The aircraft was temporarily repaired and ferried for permanent repair. Investigation by delta corporate safety determined that the tow bar disconnected due to excessive gap of the yoke due to stress over time. This can result in the hub pins diconnecting from the aircraft with a properly connected towbar. There is no process in the gse manual for the gap to be measured while in service. As a corrective action, a procedure will be developed for measurement of yoke spread on this type of tow bar ( timberline towbar ).
As the FAA filed it
ON 02/07/2013, AIRCRAFT N812SK WAS BEING REPOSITIONED FROM THE TERMINAL TO OVERNIGHT PARKING WHEN THE TOW BAR DISCONNECTED FROM THE AIRCRAFT RESULTING IN SUBSTANTIAL AIRCRAFT DAMAGE CAUSED BY THE TOW UNIT. THERE WERE NO PAX ON BOARD, AND THERE WERE NO INJURIES TO GROUND PERSONNEL. THE AIRCRAFT WAS TEMPORARILY REPAIRED AND FERRIED FOR PERMANENT REPAIR. INVESTIGATION BY DELTA CORPORATE SAFETY DETERMINED THAT THE TOW BAR DISCONNECTED DUE TO EXCESSIVE GAP OF THE YOKE DUE TO STRESS OVER TIME. THIS CAN RESULT IN THE HUB PINS DICONNECTING FROM THE AIRCRAFT WITH A PROPERLY CONNECTED TOWBAR. THERE IS NO PROCESS IN THE GSE MANUAL FOR THE GAP TO BE MEASURED WHILE IN SERVICE. AS A CORRECTIVE ACTION, A PROCEDURE WILL BE DEVELOPED FOR MEASUREMENT OF YOKE SPREAD ON THIS TYPE OF TOW BAR ( TIMBERLINE TOWBAR ).