FAA recommends inspections for more Boeing models

The U.S. Federal Aviation Administration has recommended that airlines inspect door plugs on Boeing 737-900ER jets after a blowout on another type of aircraft with a similar mid-cabin exit earlier this month.

The aviation regulator said in a statement late on Jan. 21 that operators "are encouraged to conduct a visual inspection to ensure the door plug is restrained from any movements."

The move follows the near-catastrophic mid-flight loss of a cabin door on an Alaska Airlines-operated 737 MAX on Jan. 5.

In response, U.S. regulators grounded 171 jets from the 737 MAX 9 fleet with the same configuration as the plane involved in the incident.

The FAA said it would return the 737-9 MAX to service once safety was established.

United said on Jan. 21 it was extending the cancellation of its MAX 9 flights through Jan 26. Alaska, whose MAX 9 planes account for 20 percent of its fleet, previously canceled all flights through Jan. 29.

The affected door plug panel is used to fill an unneeded emergency exit in planes, and National Transportation Safety Board investigators have suggested that the part was not affixed adequately.

Boeing's 737-900ER model is an older generation than the MAX family, but according to the FAA it has an "identical door plug design."

In its own statement, Boeing said: "We fully support the FAA and our customers in this action."

In contrast to the MAX 9 that experienced the door-plug issue which was a new plane with a low number of flights, Boeing 737-900ER aircraft have over 11 million hours of operation and 3.9 million flight cycles.