This paper presents the work carried out by GKN Westland Helicopters in the damage tolerance evaluation of the EH101 airframe. A comprehensive programme of crack growth testing and analysis was undertaken and is described in this paper. A simplified analysis method was developed and used to predict flaw growth in the Main Load Path structure of the EH101. The analysis showed that high frequency vibratory loads exceed the crack growth threshold at relatively short crack lengths. This has been confirmed by a full-scale airframe crack growth test in which a 4mm crack was propagated under representative loading. These results have led to the adoption of the Flaw Tolerant (Enhanced) Safe Life' approach for fatigue critical components on the EH101 airframe.