Flaws in jet engine fan blades like one that cracked and broke loose in April, killing a Southwest Airlines Co. passenger, have been discovered on planes operated by several carriers, and the manufacturer is moving to further tighten inspections.
General Electric Co., part of a venture that makes the engines, found a cracked blade during post-accident inspections of another Southwest plane, and spotted four or five more in those of other airlines, Southwest Chief Operating Officer Michael Van de Ven said Thursday on a conference call to discuss earnings.
“We expect to formalize the interval in a new service bulletin that will be issued in coming days,” GE spokesman Perry Bradley said in a statement. Service bulletins are non-binding recommendations on maintenance, but are almost always made mandatory by aviation regulators.
Southwest has already cut the inspection interval for older engines almost in half, from 3,000 flights to 1,600, Chief Executive Officer Gary Kelly said in an interview.
The Federal Aviation Administration said in a statement that it’s working with airlines and the engine maker. “As we receive more inspection results we may adjust the compliance time accordingly,” the agency said.
After the April 17 incident, in which a cracked blade broke off and sent debris into a window on a Southwest flight, the FAA issued a series of orders for carriers to look for cracks on all older CFM56-7B engines. The agency first required inspections on those with more than 30,000 flights, then lowered it to 20,000 flights. After that milestone, engines have to be inspected within 3,000 flights, the agency ordered in May.
The engine is made by CFM International Inc., a joint venture between General Electric Co. and France’s Safran SA.
GE determined that more frequent lubrication of the blades potentially could help avoid damage, Van de Ven said.
The tighter inspection process shouldn’t cause any airline disruptions, GE’s Bradley said. Almost all of the 14,500 CFM56-7B engines in service around the world have received their initial inspections and were cleared, he said.
GE couldn’t comment in greater detail because the failure is under investigation by the National Transportation Safety Board, he said. He wouldn’t confirm the number of cracks found on other blades, saying only “there have been a handful of findings as a result of the inspections.”
The NTSB said Tuesday that it will hold an investigative hearing on the engine’s failure, a signal the agency is giving the incident a high priority.
The Nov. 14 session will focus on the fan blades’ design and development, how that engine model is inspected, and the way debris is supposed to be contained in a failure, the NTSB said in a statement.
Jet engines are encased in hardened shells so that if fan blades or other components break loose, they won’t fly out and hit such critical areas as fuel tanks or passenger compartments.
In the April 17 incident, the fan blade bounced in front of the protective sheath, the NTSB has said. It then broke apart the unprotected engine inlet, a wing-like structure that smooths the air flow into the turbine.
Parts of the inlet showered the plane with debris. One window was struck so hard that it broke, prompting a violent decompression of the cabin and partially sucking a woman passenger out of the plane. It was the first passenger death on a U.S. carrier in more than nine years.
By Alan Levin and Mary Schlangenstein