Russia’s transport safety watchdog said it has grounded all Bell-407 light helicopters operated by Ak Bars Aero until the causes of the crash in Tatarstan on April 6 are established.

A Bell-407 of the Tatarstan government’s official flight operator vanished from radar screens. A local resident later found it in the republic’s Almetyevsk region. The pilot died.

This is the second Bell-407 crash in Russia in two months.