The manufacturer of the engine that failed catastrophically on Tuesday on a Southwest Airlines Boeing 737 issued new guidelines on Friday that call for more frequent and more thorough inspections of its engine fan blades.
The guidelines from the manufacturer, CFM International, call for ultrasonic inspections — which can detect flaws or cracks not visible to the unaided human eye — within the next 20 days to fan blades on engines with more than 30,000 cycles. A cycle includes an engine start, takeoff, landing and shutdown. The company also recommended that fan blades with 20,000 cycles be inspected by the end of August.
While airlines are not legally bound to follow a company’s guidelines, CFM said it had issued its latest service bulletin after “close coordination with the Federal Aviation Administration, European Aviation Safety Agency, Boeing” and airlines using the same type of engine involved in the failure on Tuesday. CFM, a joint venture of General Electric and the French company Safran Aircraft Engines, said it also recommended inspections of all other fan blades when they reach 20,000 cycles, and repeating the inspections every 3,000 cycles, which it said, “represents about two years in service.”
In the past two years, two Southwest Airlines 737s have had major engine failures that seemed to be the result of metal fatigue, according to evidence compiled by the National Transportation Safety Board. In both episodes, the first in 2016 and the one on Tuesday, fan blades in the planes’ engines broke apart, sending shrapnel into the plane’s body. On Tuesday, debris broke through one of the cabin windows, and one passenger died as a result.
After the 2016 incident, CFM advised airlines to perform ultrasonic inspections. The Federal Aviation Administration deemed the episode serious enough to explore imposing a new regulation — a process that was underway at the time of the failure on Tuesday.
CFM said about 14,000 engines currently in service are covered by the new inspection guidelines. Of those, it said, about 680 have at least 30,000 cycles. More than 150 of those engines have been inspected since the most recent episode, CFM said.
The company said it was providing about 500 technicians to support the accelerated inspection schedule. It estimated that an ultrasonic inspection takes about four hours per engine.