Failure analysis of ATR 72 tow bar–opportunity for re-design for inspection

Abstract

The safe towing of aircraft is an important part in aviation security. Failures during the towing and parking related operations are not so rare due to bad working circumstance, human error, etc. Tow bars are simple but very important elements, for towing aircrafts on airports all over the world. This paper describes failure analysis of accident during towing of regional ATR 72 aircraft. During towing of ATR 72 aircraft sudden fracture of shear pins caused that tow tractor goes into one and airplane ATR 72 into other direction. As a result, the airplane crashed on the empty tanker truck and severely deformed nose in this ground damage incident. Design of failed tow bar key elements and of susceptibility to corrosion was discussed in this paper. Failure analysis unveil the several key elements that lead to fracture of shear pins: outdated design of tow bar, improper maintenance and non-regular towing of aircraft. Combination of reduction of load capacity of shear pins induced by corrosion and impulse overloading caused premature fracture of the shear pins.and damage of ATR 72 aircraft. As a result of presented analysis the remedy was initiative for detail inspection of existing tow bars and redesign or purchasing the new ones. The results are presented.