In a terse statement released Wednesday, the U.S. Federal Aviation Administration (FAA) said that it will issue an airworthiness directive (AD) within the next two weeks requiring inspections of certain engines like the one that blew up on a Southwest Airlines Co. (NYSE: LUV) flight Tuesday killing one passenger. The airplane, a Boeing Co. (NYSE: BA) 737-700, was 18-years old although the engine may have been younger.
After a preliminary inspection of the failed engine, National Transportation Safety Board (NTSB) Chairman Robert Sumwalt said that one of the engines titanium fan blades had broken off and that there were signs of metal fatigue at the point of breakage.
Following a similar engine explosion in 2016, the FAA proposed an AD that would have required periodic ultrasound inspections of the engines rather than simple visual inspections. Engine manufacturer CFM International, a joint venture between General Electric Co. (NYSE: GE) and France’s Safran, had issued a service bulletin following the 2016 accident recommending that airlines conduct ultrasonic inspection of some fan blades and replace those that failed.
The proposed FAA directive in 2017 would have required ultrasonic inspections within six months of the directive’s adoption for aircraft that had flown more than 15,000 cycles (one takeoff and landing is a cycle). Engines with fewer cycles would have had to be inspected within 18 months.
That proposed directive has not been finalized in the eight months since it was proposed, according to a report in the Seattle Times.
Southwest CEO Gary Kelly said that the failed engine had reached 40,000 cycles and that it had been overhauled, as is routine, after reaching 30,000 cycles. The last routine maintenance on the engine occurred on April 15, two days before it exploded.
In addition to the broken fan blade, the engine’s cowling failed. The cowling is supposed to protect the fuselage of the plane from damage in just such an incident as happened on Tuesday. Boeing, not CFM, is responsible for the cowling.
An extensive NTSB investigation into Tuesday’s incident is expected to take 12 to 15 months.