http://news.bbcnewsd73hkzno2ini43t4gblxvycyac5aw4gnv7t2rccijh7745uqd.onion/2/hi/uk_news/8621407.stm
"Firstly it is highly abrasive and can scour and damage moving parts. Secondly, if it enters a jet engine the intense heat of the engine can fuse it to the interior of the engine with a caking of hot glass, which ultimately can cause the engine to cut out completely.