New Delhi, Jan 9 (IANS): The Directorate General of Civil Aviation (DGCA) on Tuesday said that a critical washer was discovered missing during recent checks on a Boeing 737 MAX operated by an Indian carrier.

This comes after Alaska Airlines grounded all of its Boeing 737-9 aircraft after one plane had to make an emergency landing in Portland, Oregon, with a window and a part of the fuselage missing.

The US aerospace giant issued a global advisory late last month, urging MAX operators to conduct thorough inspections for loose hardware. The focus was particularly on nuts securing tie rods responsible for controlling the rudder movement.

"Based on information from an operator of a missing nut and washer in the Aft Rudder Quadrant on Boeing 737MAX airplane, Boeing has recommended for a one-time inspection of all Boeing 737MAX airplanes before January 10 for possible loose hardware," the aviation watchdog's Director General, Vikram Dev Dutt said.

Indian Boeing 737MAX fleet of 40 is operated by Akasa (22), Spicejet (9) and Air India Express (9).

"Inspections on 39 aircraft have been completed with nil findings except on one aircraft wherein a missing washer was found. Rectification action as per recommendations of Boeing has been taken prior to release of this aircraft. Inspection on the remaining one aircraft will be completed prior to release for service," said Dutt.