The US Federal Aviation Administration (FAA) is reviewing two potential quality-control problems in the manufacture of the Boeing 787 Dreamliner that may go back almost 10 years.

Boeing said shims, or material used to fill empty spaces between parts and align them, weren't correctly sized in the rear fuselage of the plane. A second issue involved a failure to meet "skin flatness specifications" in some parts of the assembled aircraft.

The FAA could require additional inspections of about 900 of the approximately 1,000 Dreamliners delivered since 2011.

So far, only eight planes have been grounded and the FAA hasn't issued an order covering the entire 787 fleet.

The Wall Street Journal, which first reported the problems, said eight planes were grounded in late August because they didn't meet "requirements for safe flight and landing".

Only aircraft with both manufacturing problems were grounded. Planes that had only one flaw were allowed to remain in service because they met load-capacity requirements.

The airlines involved in the groundings are Air Canada, United Airlines, All Nippon Airways, Singapore Airlines, Air Europa, Norwegian Air Shuttle and Etihad Airways.

The 787 Dreamliner is a wide-body jet designed for international travel. It seats 258 to 336 passengers depending on the model and cabin configuration. The jet has a range of 7,305 nautical miles (13,540 kilometers).

Regulators are planning no immediate action for the entire 787 fleet. Boeing voluntarily told the airlines to ground eight planes and make immediate repairs to correct the combined defects, the Journal reported.

In a statement, Boeing said the two parts produced at the company's South Carolina plant independently met load requirements, but when combined "result in a condition that does not meet our design standards".

Boeing said it notified the FAA and "immediately contacted" the airlines.

"Safety and quality are Boeing's highest priorities; we are taking the appropriate steps to resolve these issues and prevent them from happening again," Boeing said in the statement.

Boeing said it also discovered a problem with how parts of the 787's horizontal stabilizer, or short rear wing, were clamped together during construction.

The company said it told the FAA.

"We are correcting the issue on airplanes that have not been delivered," Boeing said in a statement. "Analysis is underway to determine if action is required on the in-service fleet."

Boeing produced 14 Dreamliners a month prior to the novel coronavirus pandemic. It then cut production to 10 per month and plans to produce six per month in 2021, the Seattle Times reported.

Demand for air travel has collapsed during the pandemic. Airlines have cut flights, canceled orders for new jets and furloughed workers.

The defects may add to the regulatory issues facing Boeing since two crashes of its top-selling 737 MAX in Indonesia and Ethiopia killed all 346 passengers and crew.

The MAX has been grounded worldwide since March 2019. The FAA is reviewing the plane's updated software, but there is no scheduled date to return the jet to service.