Engineering Investigation of Failures of Cable Used to Tow the TDU-32A Banner Target from T2C Aircraft

摘要

Twice in May of 2000, cables used to tow TDU-32A target banners broke while being towed by T2C aircraft of VT-9 flying out of Meridian MS. There had been two similar incidents in the preceding 20 months. In each case the cable broke about thirteen feet aft of the tow point on the aircraft and the banner portion of the cable was not recovered. The breaks occurred or were first noticed following turns. This pattern of cable breakage caused an engineering investigation to be initiated. Because the break point was just aft of the T2C exhaust, it was suspected that the cable had entered the exhaust during a turn or had contacted the aircraft in the vicinity of the exhaust and that this had caused or contributed to the breakage. The immediate response of the Commanding Officer was to restrict the aircraft to bank angles of less than 30 deg when towing banners. The purpose of this engineering investigation was to determine the cause of the cable breakage and to recommend action that would obviate further occurrences. The position of the break along the cable indicated that the failure was related to either heating by the exhaust or by abrasion or stress concentration in the cable due to contact with the aircraft in the vicinity of the exhaust. Cable of substandard mechanical properties might also contribute.