An Iran Aseman Fokker 100, registration EP-ATF performing flight EP-626 from Tehran Mehrabad to Kermanshah (Iran) with 92 passengers and 7 crew, was climbing through FL170 out of Tehran when the crew needed to shut the left hand engines (Tay 650) down. The aircraft returned to Mehrabad Airport for a safe landing about 25 minutes after departure.
On Jun 3rd 2020 Iran's AIB reported the crew encountered difficulty to climb the aircraft any further at 13,000 feet, the left hand engine showed high engine oil temperatures. After working the related checklist procedures the condition of the engine did not improve prompting the crew to stop the climb, shut the engine down and return to Mehrabad Airport.
Authorized Company Maintenance identified issues in the connections of the display system and replaced a number of components. The engine was subsequently tested with no faults, a test flight without passengers was performed also without any faults.
On May 31st 2020 the aircraft was scheduled to perform another 4 flights, however, suffered the same fault again on the 4th flight, see Incident: Iran Aseman F100 at Ahwaz on May 31st 2020, engine shut down in flight.
Iran's AIB opened an investigation into the occurrences.