Boeing halts test flight of new plane (737 MAX 8)

From aviation week:

LOS ANGELES—Flight tests of Boeing 737 MAX aircraft are expected to resume shortly after being suspended for several days. This followed the discovery of cracks in part of a low-pressure (LP) turbine section destined for one of the CFM Leap-1B engines that power the new aircraft.

Boeing and CFM are inspecting the second and third LP turbine stage discs of a suspect population of Leap-1Bs. Boeing said it remains confident that delivery of the first 737-8 to Lion Air group carrier Malindo Air, will still take place later this month. The issue—which Boeing said is a manufacturing quality-control problem restricted to a specific batch of parts rather than a more serious fundamental design flaw—was flagged up by the disc supplier during a routine quality inspection. Boeing was first notified in the first week of May.

The company said the decision to temporarily suspend flights of 737 MAX aircraft, which includes pre-delivery check flights of the 737-8 and testing of the stretched 737-9, which debuted only in April, was made out of “an abundance of caution.” Boeing also stresses that no engine issues related to the LP turbine have been detected during flight or ground tests.

Boeing said it is working with CFM to “understand the precise scope and root cause of the quality issue.” In the meantime Boeing said the gradual acceleration of the 737 MAX production line will continue uninterrupted, as will production and delivery of the current production 737NG.

Part of the uncertainty over the full impact on both the delivery and flight-test schedules hinges on knowing the extent of the affected engine fleet. Boeing, CFM and the unidentified supplier are tracking the paperwork for the affected parts. They are determining which engines have a clean bill of health, which are suspect and which will require removal for inspection.

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