A week after the National Transportation Safety Board urgently recommended that all GEnx engines be inspected for drive-shaft cracks before further flight and repetitively thereafter, the Federal Aviation Administration will make those suggestions binding law.
On Thursday the FAA filed its “airworthiness directive” regarding the engines, which power every Boeing 787 made in South Carolina so far, and its mandates go into effect today.
The directive follows two GEnx engine failures this summer — the first during a local 787’s pre-flight test at Charleston International Airport — and the discovery of a crack in a third engine’s fan midshaft.
“We are issuing this AD to prevent failure of the FMS resulting in one or more engine failure(s) and possible loss of the airplane,” the FAA said in the directive.
GE and Boeing issued statements Thursday noting that all of the 14 GEnx-1B engines, which power 787s, and all 114 GEnx-2B engines, which power 747-8s, that have been delivered to airlines so far have been inspected.
According to the new directive, those engines’ fan midshafts must now be inspected again within 90 days. The FAA estimated the cost of the ultrasonic inspection equipment at $105,000 each, and that each inspection would take nine hours to complete.
In a statement, GE said the FAA AD follows the company’s recommendations and played down the effect it will have on airlines. GE spokesman Rick Kennedy added that the inspection costs would be shared between the manufacturer and the airlines.
“GE expects that these inspections can be conducted without disrupting service of GEnx operators,” the company said, adding that each inspection can be performed while the engine remains on the wing and takes “about two to three hours” to complete.
Carter Leake, who covers the aerospace and defense industries for BB&T Capital Markets, said the difference in time estimates is likely the difference between an initial inspection and subsequent checks.
Boeing released a statement echoing GE’s expectation that airlines will not be disrupted and pledging continuing cooperation.
The FAA directive also repeated the likely cause of the cracking floated last week by the NTSB.
“Root cause is still under investigation, but the failure of the FMS is likely due to environmentally assisted cracking; a type of corrosive cracking that is time-dependent,” the statement said.
GE said it has tweaked its production process to address that issue, “including changes to the dry-film coating applied to the midshaft at the manufacturing stage, as well as changes to the assembly lubricant used when the retaining nut is clamped to the midshaft.”
GE had changed coatings to reduce lead content for environmental reasons, Kennedy said.
Leake, who is based in Richmond and has a buy rating on Boeing, said the 90-day interval represented a “thumbs up.”
“I think the takeaway is ... such confidence,” he said. “There’s no concern here.”
Leake said his previous anxiety about a possible reduction in the GEnx-powered 787’s extended operations (ETOPS) rating now seems “overdone.”
Friday’s FAA directive pertains only to the 11 GEnx engines registered in the U.S. Regulatory agencies in the countries where the rest of the engines are registered are free to make their own rules, Leake noted, but they typically follow the FAA’s lead.
“From what we read here, it’s probably safe to conclude that Boeing sort of dodged a bullet here and is in the clear,” he said.