A time when an extraneous task suddenly wound up on the critical path for the project is the discovery of Scotchgard stain repellent. Patsy Sherman, a researcher, who worked at 3M company as a chemist was assigned to work on fluorochemicals to develop a new kind of rubber for jet aircraft fuel lines. An assistant had accidently spilled a bottle of synthetic latex that Sherman had made on to his tennis shoes. It was discovered that the substance did not change the look of the shoes. Moreover, it could not be washed away by any solvent and repelled water, oil and other liquids. This accidently discovery lead 3M to investigate more money to further research this substance. Consequently, the 3M company decided to produced versatile fabric stain repellent and material protector, Scotchgard out of the substance Sherman made. Thus, Scotchgard is an example of a product that was meant for rubber of a jet but became got on a critical path of another project dealing with a fabric stain repellent.
Reference:
http://www.women-inventors.com/Patsy-Sherman.asp