2nd site exercise at Knottingley using P.B.I. 26-27 September 1981 (IM-TD-024)

The annular loading system on the rear measuring position of the P.B.I on the right hand side of the vehicle, ceased to function satisfactorily after the initial proving and measuring run, and prior to the start of the stone blowing exercise. The measuring run was repeated using the full load...