NONE · AIRBUS A220 · 2020-02-12 · Bordeaux, OF, FR
Event
NTSB number
ENG20LA015
Event ID
20200212X95117
Type
Incident
Date
2020-02-12
Location
Bordeaux, OF, FR
Coordinates
44.83077, -0.577698
Injuries
Highest injury
NONE
Fatal
0
Serious
0
Minor
0
Uninjured
154
Total aboard
154
Aircraft
Make
AIRBUS
Model
A220
Registration
YL-AAU
FAR Part
NUSC
Engines
2
Damage
—
Conditions
Light
DAYL
Weather
Unk
Probable cause
A No. 1 (left) engine low pressure compressor (LPC) stage 1 integrally bladed rotor (IBR) separation due to a high cycle fatigue crack (HCF) that originated at the runout of an airfoil leading edge root radius. The HCF crack developed because of a mechanically coupled LPC stage 3 and stage 1 IBR mode excitation and blade flutter response. The excitation was driven by an acoustic tone generated by turbulent airflow passing over the 2.5 bleed valve duct cavity while the engine was operating at high speeds in specific flight conditions. A primary contributor to the failure mode was an electronic engine control (EEC) software update that changed the LPC vane schedule and increased the likelihood of LPC stage 1 IBR blade flutter onset within the engine operating range.