Company officials say they will investigate after a Boeing plane operated by United Airlines was found to be missing an external panel when it landed in Medford, Oregon, on Friday.

The plane initially took off from San Francisco International Airport (SFO), NBC Bay Area reported, citing a statement from United which said the airport in Medford was its destination.

“After the aircraft was parked at the gate, it was discovered to be missing an external panel. We’ll conduct a thorough examination of the plane and perform all the needed repairs before it returns to service. We’ll also conduct an investigation to better understand how this damage occurred,” the statement noted.

There were 139 passengers and six crew members on board the Boeing 737-800. However, an emergency was not declared because there was no indication of damage as its journey progressed.

An image shows the exposed insides of the plane where the panel should have been after its landing:

Authorities at the Medford airport said the flight tower shut down flight operations to clear the runways, but Rogue Valley International Medford Airport director Amber Judd said they did not find any kind of debris or panels, therefore, the airport eventually resumed operations.

“The incident involving United Airlines flight 433 is the latest in a string of recent mechanical problems on United airplanes,” the NBC article said, highlighting several recent incidents that were connected to SFO.

On Wednesday, a Boeing plane operated by American Airlines made an emergency landing at Los Angeles International Airport (LAX) after what was deemed a “possible mechanical issue,” per Breitbart News.

The news came after a former Boeing employee who became a whistleblower against the company was found dead recently from what officials called a “self-inflicted wound.”

Sixty-two-year-old John Barnett had been giving evidence in a lawsuit against the company after having worked for the company as a quality manager at the North Charleston plant where the 787 Dreamliner was made.

Per the BBC:

In 2019, Mr. Barnett told the BBC that under-pressure workers had been deliberately fitting sub-standard parts to aircraft on the production line.

He also said he had uncovered serious problems with oxygen systems, which could mean one in four breathing masks would not work in an emergency.

Barnett is said to have “made powerful enemies” during his 32-year-long career, according to a Breitbart News report published on Friday.