The United States’ air transportation agency Federal Aviation Administration (FAA) has ordered immediate inspections of Boeing 777 planes with Pratt & Whitney PW4000 engines before further flights after an engine failed on a United Airlines flight recently.
Operators must conduct a thermal acoustic image inspection of the large titanium fan blades located at the front of each engine, the FAA said.
Recently, the National Transportation Safety Board (NTSB), the independent US government investigative agency responsible for civil transportation accident investigation, said that a cracked fan blade from the United Flight 328 engine that caught fire was consistent with metal fatigue.
“Based on the initial results as we receive them, as well as other data gained from the ongoing investigation, the FAA may revise this directive to set a new interval for this inspection or subsequent ones,” the FAA said.
The engine that failed on the 26-year-old Boeing 777 and shed parts over a Denver (Colorado) suburb last week was a PW4000. Fortunately, the engines are used on 128 planes, or less than 10 percent of the global fleet of more than 1,600 delivered 777 widebody jets.
In March 2019, after a 2018 United Airlines engine failure was caused due to fan blade fatigue, the FAA ordered inspections every 6,500 cycles. A cycle is one take-off and landing. An airline would typically accumulate 1,000 cycles about every 10 months on a 777, according to an industry source familiar with the matter.
South Korea’s transport ministry said that it had told its airlines to inspect the fan blades every 1,000 cycles following guidance after the latest United incident. Meanwhile, Korean Air and Asiana Airlines said they would comply with the relevant authorities’ directives.
The FAA said in 2019 that each inspection was expected to take 22 man-hours and cost $1,870.
American aerospace company Boeing said it supported the FAA’s latest inspection guidance and would work through the process with its customers. It had earlier recommended that airlines suspend the use of the planes while the FAA identified an appropriate inspection protocol, and Japan imposed a temporary suspension on flights after the incident.