US safety investigators have confirmed an uncontained failure of a GE Aviation GE90-85B engine led to a fire and aborted take-off of a British Airways Boeing 777-200 in Las Vegas last month.

Meanwhile, the engine manufacturer is performing “focused inspections” on other GE90s as part of the investigation, says the US National Transportation Safety Board, which on 6 October published the first update from the investigation in three weeks.

“The inspection data is being gathered to support the investigation and to determine further investigative actions,” the NTSB says.

GE is inspecting 38 GE90s of similar vintage as the engined involved in the 8 September incident at McCarran International Airport in Las Vegas, Nevada. All 38 engines are in storage, according to GE.

The affected engine was manufactured in 1995, the year the 777 entered service, making it among the oldest GE90s in operation, according to GE. About 176 engines are in still in service from the original series that featured 312cm (123in) fan diameter, versus the 325cm fan diameter of the later GE90-115B model, the company says.

An internal explosion that originated in a section of the high pressure compressor caused parts to breach the engine case and cowling, the NTSB says.

A fracture began in the Stage 8 disk web of the high-pressure compressor section, the NTSB says. According to GE, the disk web is a structure lying between each of 10 stages of compressor disks. It connects the disk post, which holds the compressor blades, to the disk bore.

The NTSB has retrieved all of the pieces of the fragmented Stage 8 disk rim, including some fragments that remained inside the engine, the agency adds.

The update offers the first official confirmation that the GE90 suffered an uncontained engine failure during the incident. Such events are extremely rare and previously unprecedented on the GE90. Engine certification requirements are intended to render the chances of an uncontained compressor failure as less than one in a billion.

The findings also differ from speculation in some media reports, citing a 2011 warning by the US Federal Aviation Administration. That airworthiness directive called on GE90-85B operators to check for cracks in weld joints between stages 9 and 10 of the high pressure compressor. But the directive warned that such cracks could lead to an uncontained failure, a point disputed in the text of the airworthiness directive by GE Aviation and Boeing.

GE also has clarified that the 2011 airworthiness directive applied to a newer configuration of the GE90-85B than the engine installed on the British Airways 777-200 that failed in Las Vegas on 8 September.

The pilot of the 777-200 aborted a take-off roll moments after the engine failure. Passengers and flight crew evacuated onto the runway, with a few minor injuries reported.

[Article was updated with GE comments at 3pm.]

Source: Cirium Dashboard