The Israeli air force is to slash the interval for replacing tail rotor blades on its Boeing AH-64 Apache attack helicopters, after a 7.8in (20cm)-long crack was found during a routine inspection last month.

Air force commander Maj Gen Amir Eshel ordered a temporary grounding of the Apache fleet while an investigation was conducted in co-operation with the US Army and Boeing. The process also included X-ray inspections intended to detect even the smallest crack. Individual aircraft were returned to flight status following these checks.

As a result of the inspections, the air force has decided to replace tail rotors after 995 flight hours, rather than a previous interval of every 4,600h.

The step comes as the service on 5 July lifted a two-day suspension of all training flights, also ordered by Eshel. This was imposed after an accumulation of safety incidents in recent weeks, with the pause used to refresh safety procedures.