Loss of engine cover on Southwest Boeing 737-800 prompts FAA investigation

WATCH: Engine cover detaches from plane Passenger video shows an engine cowling becoming detached during a Southwest flight during takeoff from Denver.

WASHINGTON — An engine cover on a Southwest Airlines Boeing 737-800 fell off on Sunday during takeoff in Denver and struck the wing flap, prompting the U.S. FAA to open an investigation.

No one was injured and Southwest Flight 3695 returned safely to Denver International Airport around 8:15 a.m. local time on Sunday and was towed to the gate after losing the engine cowling.

The Boeing aircraft bound for Houston Hobby airport with 135 passengers and six crew members aboard rose to an elevation of about 10,300 feet (3,140 metres) before returning 25 minutes after takeoff.

Passengers arrived in Houston on another Southwest plane about four hours behind schedule. Southwest said maintenance teams are reviewing the aircraft.

The plane entered service in June 2015, according to FAA records. Boeing referred questions to Southwest. The airline declined to say when the plane's engine had last had maintenance.

ABC News aired a video posted on social media platform X of the ripped engine cover flapping in the wind with a torn Southwest logo.

Boeing has come under intense criticism since a door plug panel tore off a new Alaska Airlines 737 MAX 9 jet at 16,000 feet on Jan. 5.

In the aftermath of that incident, the FAA grounded the MAX 9 for several weeks, barred Boeing from increasing the MAX production rate and ordered it to develop a comprehensive plan to address "systemic quality-control issues" within 90 days.

Boeing production has fallen below the maximum 38 MAX planes per month the FAA is allowing. The Justice Department has opened a criminal investigation into the MAX 9 incident.

The 737-800 is in the prior generation of the best-selling 737 known as the 737 NG, which in turn was replaced by the 737 MAX.

The FAA is investigating several other recent Southwest Boeing engine issues.

A Southwest 737 flight on Thursday aborted takeoff and taxied back to the gate at Lubbock airport in Texas after the crew reported engine issues. The FAA is also investigating a March 25 Southwest 737 flight that returned to the Austin airport in Texas after the crew reported a possible engine issue.

A March 22 Southwest 737-800 flight returned to Fort Lauderdale airport after the crew reported an engine issue. It is also being reviewed by the FAA.

Reporting by David Shepardson in Washington and Urvi Dugar in Bengaluru; Editing by Lisa Shumaker, Matthew Lewis and Mark Porter