Regulators Want a Closer Look at the Fan Blades on Older 737s

European and US regulators are drawing fresh attention to fan blade cracking on the CFM56-7B, the engine that powers Boeing’s 737 Next Generation family. FlightGlobal reported on October 26 that EASA and the FAA warn that when a blade breaks, debris can be released forward and uncontained, with the potential to damage the aircraft fuselage. The agencies are using the warning to back an inspection directive for operators of the type.

The background is the 2018 Southwest Airlines Flight 1380 accident, in which a fan blade fractured at its root, or dovetail, and a passenger died after debris breached a cabin window. Investigators tied the failure to a fatigue crack that the inspection method then in use probably missed. Since then, operators have had to inspect blades repeatedly, and later rules required a redesigned engine inlet to improve debris containment, with compliance due by 2028.

A proposal the FAA published on July 31 would go further. It would replace the 2018 directive for roughly 4,553 CFM56-7B engines on US-registered aircraft, extending inspections to both sides of the blade dovetail and enlarging the ultrasonic inspection area. Blades would be inspected before reaching 17,000 cycles and then at least every 1,600 cycles. The FAA estimates the inspection at about $340 per engine, while replacing a blade pair would cost around $208,385.

EASA issued a matching proposal on July 30 that sets repeat ultrasonic checks every 1,600 flight cycles for most engines and every 500 cycles for two sub-types. The push followed a July 10 failure on a Malta Air 737-800 flying as Ryanair FR1879, although the FAA said it had no information linking that event to the unsafe condition and its cause is still under investigation. For passengers, nothing about booked flights changes, since the measures concern maintenance schedules for the engines rather than flight bans.

Sources: FlightGlobal, EASA proposed directive PAD 26-091