Medical devices and airport scanners maker Smiths Group took a tumble late on Tuesday after it announced that trading at Smiths Detection has fallen short of expectations.Shares dropped nearly 6% in the afternoon session following the announcement which also revealed that the divisional president Stephen Phipson will leave with immediate effect, and the group is already looking for a permanent replacement.The statement said that continued order delays at the division - which develops X-ray inspection systems, metal detectors and mobile explosive detection systems - have had an impact on its second half performance."Looking to the full year for Smiths Detection, the sales trends seen in the first half are likely to continue through the balance of the year, while full year margins may be affected by the associated operational gearing," the group said.Smiths Group said that guidance for its other divisions remains unchanged.---BC