Pilot Debrief

Airbus Industrie A320-211 near Chicago, IL — 2011-09-17

Final reportCEN11IA649
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Date
2011-09-17
Location
Chicago, IL, USA
Airport
ORD
Aircraft
Airbus Industrie A320-211
Registration
C-FGYL
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Cruise

Probable cause

The infiltration of moisture into the windshield heating layer that induced arcing in the heating system that subsequently cracked the windshield.

NTSB narrative

The first officer's (FO) windshield cracked during cruise flight. The crack subsequently progressed into multiple multidirectional cracks that obscured the FO’s view through the window. The flight crew was unable to determine the severity of the cracks and diverted without further incident. A postincident examination of the windshield revealed an area of arcing located along the electrical bus bar at the lower edge of the windshield, near the forward corner. This location coincided with the area in which the power and sensing element wires were routed around the structural glass plies. The area of arcing was surrounded by a cloudy and degraded interlayer, which was consistent with the presence of moisture. A section of the moisture seal was worn and appeared to have been repaired, resulting in moisture ingress. The moisture degraded the interlayer and electrical system resulting in a discontinuity that led to electrical arcing and failure of the heating system causing the windshield cracking. The latest windshield revisions, with part numbers NP-165331-1/-2, are available and include enhancements that reduce the potential for moisture ingress and its subsequent effects on the electrical system.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Flight crew could have checked the inner ply for cracks earlier to assess severity.

NTSB coding

  • Sys/Comp malf/fail (non-power) · Enroute-cruise

Evidence available

  • FDR / data
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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