One of Southwest Airlines’ Boeing 737-800s has returned to Denver, its departure airport, after one engine suffered an apparent cowl-door detachment.

The aircraft had been operating the WN3695 service to Houston on 7 March.

It had taken off from Denver’s runway 25.

But air-ground communications indicate that the crew sought to level at 10,000ft after encountering a problem.

“We’re going to need some time,” one of the pilots told Denver departure control, according to a radio exchange archived by LiveATC.

“For now everything’s OK. We don’t even know the nature of it, but apparently several passengers and flight attendants heard something loud hit the wing.”

The pilot added that the crew was going to take some time to understand the issue.

Southwest 737 N8668A-c-Alan Wilson Creative Commons

Source: Alan Wilson/Creative Commons

Pictures captured by those on board the aircraft indicate it lost its right-hand CFM56 cowl doors

Images purporting to have been captured by those on board the aircraft suggest the cowl doors of the right-hand CFM International CFM56 engine were torn off.

“Right now the [aircraft] is flying just fine – we do definitely want to get it down, but we just want to make sure we have our ducks in a row,” the crew informed departure control.

After checking with controllers over the wind situation for runway 26, the crew stated that the “numbers don’t look good”. With flaps up and a heavy gross weight, they added that they “can’t make 26 work”, requesting runway 34L instead.

The aircraft touched down on 34L about 25min after take-off.

Although the circumstances have yet to become clear, occurrences of engine cowl loss on take-off have frequently been attributed to latches on the cowl doors not having been secured – leading to such prevention measures as brightly-painted cowls and special keys which cannot be removed without the cowl being locked.