Failure of Dowel Bolts of MIG-21 Aircraft

摘要

The spur and bevel gears of R-11 engine fitted on MIG-21udaircraft are fastened together by a set of six dowel bolts .udA series of accidents caused by the failure of the doweludbolts had been reported . Bolts from five engines were examined in detail . The tell-tale marks on the gear assembly and on the fracture surface clearly indicate that there existed a gap between the gears leading to relative motion between the bolts and the bevel gear, resulting in fatigue failure.