March 15 (Reuters) - United Airlines on Friday

said one of its Boeing 737-800 aircraft was found to have

a missing external panel after landing safely at its scheduled

destination at Rogue Valley International Medford Airport in

Oregon.

United said the plane was carrying 139 passengers and six

crew, and the missing panel was discovered after the plane was

parked at the gate.

"We'll conduct a thorough examination of the plane and

perform all the needed repairs before it returns to service,"

the airline said in a statement, adding it will also investigate

to understand the cause of the incident.

Boeing ( BA ) did not comment, directing questions to United

Airlines.

The plane had departed from San Francisco, according to

flight tracking website FlightRadar24.

Last week a United Airlines-operated Boeing 737 MAX

rolled onto the grass

and off the runway at George Bush Airport in Houston, and

the incident was being investigated by the National

Transportation Safety Board and the Federal Aviation

Administration.

Boeing ( BA ) has been under heavy regulatory scrutiny

following a Jan. 5 Alaska Airlines mid-air panel

blowout, with probes into the company's safety and quality

standards in its production process.