DENVER (KDVR) — The Federal Aviation Administration announced Tuesday evening that it is ordering inspections of all Pratt & Whitney PW4000 engines — the same kind that failed on a United Boeing 777 shortly after it took off from Denver on Saturday.

Airlines are forbidden from flying planes with PW4000 engines until they are inspected.

United 328 had just left Denver International Airport for Honolulu on Saturday when the plane’s right engine failed, causing metal to rain down on the city’s northwest suburbs. The plane returned to DIA and no injuries were reported.

“Although the aircraft landed safely, the failure resulted in damage to the engine, an in-flight engine fire, and damage to the airplane,” the FAA said in a statement. “After reviewing the available data and considering other safety factors, the FAA determined that operators must conduct a thermal acoustic image (TAI) inspection of the large titanium fan blades located at the front of each engine. TAI technology can detect cracks on the interior surfaces of the hollow fan blades, or in areas that cannot be seen during a visual inspection.”

The agency said it will review the results of the inspections on a rolling basis. Depending on the results of the investigation, the FAA may require the engines to be inspected more frequently.

“The previous inspection interval for this engine was 6,500 flight cycles. A flight cycle is defined as one takeoff and landing,” the FAA said.

The agency’s order is effective immediately. It said it is sharing the information with similar aviation agencies in other countries.

United issued the following statement on Tuesday evening:

“On Sunday, we voluntarily removed 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from our schedule. We’ve been working with the NTSB on their investigation and will comply with the FAA’s Emergency Airworthiness Directive to ensure all 52 of the impacted aircraft in our fleet meet our rigorous safety standards.”