NONE · BOEING 737 7H4 · 2017-06-03 · Washington, DC, USA
Event
NTSB number
ENG17IA027
Event ID
20170608X90705
Type
Incident
Date
2017-06-03
Location
Washington, DC, USA
Coordinates
38.948612, -77.450279
Injuries
Highest injury
NONE
Fatal
0
Serious
0
Minor
0
Uninjured
67
Total aboard
67
Aircraft
Make
BOEING
Model
737 7H4
Registration
N765SW
FAR Part
121
Engines
2
Damage
MINR
Conditions
Light
DAYL
Weather
Unk
Probable cause
The failure the control alternator gearshaft, which disconnected the accessory gearbox from the rest of the engine and resulted in an uncommanded in-flight shutdown of the left engine and subsequent flight diversion. The control alternator gearshaft failed because of high cycle fatigue intergranular corrosion cracking. Contributing to the failure of the control alternator gearshaft were additional manufacturing processing steps to address part non-conformances that reduced its high cycle fatigue capability and potential change in vibratory environment since the last shop visit.