National Transportation Safety Board
Aviation Incident Final Report

 

 

Location:

Chicago, IL

Incident Number:

CEN11IA649

Date & Time:

09/17/2011, 1045 CDT

Registration:

C-FGYL

Aircraft:

Airbus Industrie A320-211

Aircraft Damage:

Minor

Defining Event:

Sys/Comp malf/fail (non-power)

Injuries:

140 None

Flight Conducted Under:

Part 129: Foreign

Analysis

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.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this incident to be:
The infiltration of moisture into the windshield heating layer that induced arcing in the heating system that subsequently cracked the windshield.

Findings

Aircraft

Flight compartment windows - Failure (Cause)

Flight compartment windows - Design

Factual Information

On September 17, 2011, about 1045 central daylight time, an Airbus Industrie A320, C-FGYL, sustained minor damage when the copilot’s window cracked during cruise at flight level 340 northwest of Chicago, Illinois. The flight crew declared an emergency, and diverted to the Chicago O'Hare International Airport (ORD), Chicago, Illinois, landing about 1113 without further incident. There were no injuries to the 2 flight crewmembers, 4 cabin crewmembers, and 134 passengers. The airplane was registered to GECAS and the flight was operated by Air Canada as flight 791, under the provisions of 14 Code of Federal Regulations Part 129 as a scheduled international passenger flight. Day visual flight rules conditions prevailed for the flight, which operated on an activated instrument flight rules flight plan. The flight originated from the Toronto Pearson International Airport, near Toronto, Ontario, Canada, about 0940, and was destined for the Los Angeles International Airport, near Los Angeles, California.

The operator’s incident report stated an 18-inch long crack developed in the first officer’s (FO) windshield, extending from the left bottom corner to the top right corner, during cruise flight. The crack subsequently progressed into multiple multi directional cracks that obscured the FO’s view through the window. The flight crew was unable to determine the severity of the cracks and how many plies were affected. The flight crew complied with the quick reference handbook guidance and diverted to ORD. The flight crew performed an overweight landing and taxied the airplane to the gate.

The incident windshield, part number NP-165311-8 with serial number 07169H9453; CA122417, was made from laminated glass. The layers, from the outboard surface to the inboard surface; included a Herculite II glass layer coated with a Nesatron anti-ice system and its associated conductive bus bar, a urethane interlayer, a vinyl interlayer, a urethane interlayer, a Herculite II glass layer, a vinyl interlayer, and a Herculite II glass layer.

A NTSB aircraft structures and maintenance specialist oversaw a postincident examination of the windshield at PPG Industries, Inc., near Huntsville, Alabama, on March 9, 2012. The examination revealed that the fracture origin was located at the center of the windshield. An area of arcing was 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. This area of arcing was surrounded by a cloudy and degraded interlayer, which was consistent with the presence of moisture. The moisture seal was worn and the moisture seal upper edge had been repaired. Appearance of the moisture seal’s forward and lower edges was consistent with a factory condition.

The latest windshield revisions produced by PPG Aerospace, with part numbers NP-165331-1/-2, are now available and include enhancements that reduce moisture ingress and its subsequent effects on the electrical system.

According the Accredited Representative from the Bureau d’Enquêtes et d’Analyses (BEA), Airbus had issued a Flight Operation Telex (FOT) on May 25, 2011, to inform operators about the issuance of a revised Cockpit Windshield/ Window Cracked operational procedure in case of a cockpit window cracking. The new procedure asked the crew to check if the inner ply is affected by the crack by using either a pen or finger nail. If the inner ply is not cracked, based on the fail safe design, the flight crew can continue the flight, without other restriction.

 

History of Flight

Enroute-cruise

Sys/Comp malf/fail (non-power) (Defining event)

 

 

Pilot Information

Certificate:

Airline Transport

Age:

50, Male

Airplane Rating(s):

Multi-engine Land

Seat Occupied:

Left

Other Aircraft Rating(s):

 

Restraint Used:

Seatbelt, Shoulder harness

Instrument Rating(s):

Airplane

Second Pilot Present:

Yes

Instructor Rating(s):

 

Toxicology Performed:

No

Medical Certification:

Class 1 Without Waivers/Limitations

Last FAA Medical Exam:

08/17/2011

Occupational Pilot:

Yes

Last Flight Review or Equivalent:

05/17/2011

Flight Time:

10809 hours (Total, all aircraft)

 

 

Co-Pilot Information

Certificate:

Airline Transport

Age:

38, Male

Airplane Rating(s):

Multi-engine Land

Seat Occupied:

Right

Other Aircraft Rating(s):

 

Restraint Used:

Seatbelt, Shoulder harness

Instrument Rating(s):

Airplane

Second Pilot Present:

Yes

Instructor Rating(s):

 

Toxicology Performed:

No

Medical Certification:

Class 1 Without Waivers/Limitations

Last FAA Medical Exam:

01/14/2011

Occupational Pilot:

Yes

Last Flight Review or Equivalent:

08/07/2011

Flight Time:

5419 hours (Total, all aircraft)

 

 

Aircraft and Owner/Operator Information

Aircraft Make:

Airbus Industrie

Registration:

C-FGYL

Model/Series:

A320-211

Aircraft Category:

Airplane

Year of Manufacture:

 

Amateur Built:

No

Airworthiness Certificate:

Transport

Serial Number:

MSN 254

Landing Gear Type:

Retractable - Tricycle

Seats:

147

Date/Type of Last Inspection:

09/16/2011, AAIP

Certified Max Gross Wt.:

169500 lbs

Time Since Last Inspection:

 

Engines:

2 Turbo Fan

Airframe Total Time:

49660 Hours at time of accident

Engine Manufacturer:

CFM

ELT:

Installed, not activated

Engine Model/Series:

56-5A

Registered Owner:

GECAS

Rated Power:

 

Operator:

AIR CANADA

Operating Certificate(s) Held:

Foreign Air Carrier (129)

Operator Does Business As:

 

Operator Designator Code:

ARNF

 

Meteorological Information and Flight Plan

Conditions at Accident Site:

Visual Conditions

Condition of Light:

Day

Observation Facility, Elevation:

ORD, 672 ft msl

Distance from Accident Site:

93 Nautical Miles

Observation Time:

1051 CDT

Direction from Accident Site:

130°

Lowest Cloud Condition:

Few / 4200 ft agl

Visibility

10 Miles

Lowest Ceiling:

None

Visibility (RVR):

 

Wind Speed/Gusts:

5 knots /

Turbulence Type Forecast/Actual:

/

Wind Direction:

Variable

Turbulence Severity Forecast/Actual:

/

Altimeter Setting:

30.31 inches Hg

Temperature/Dew Point:

17°C / 6°C

Precipitation and Obscuration:

No Obscuration; No Precipitation

Departure Point:

Toronto (CYYZ)

Type of Flight Plan Filed:

IFR

Destination:

Los Angeles, CA (LAX)

Type of Clearance:

IFR

Departure Time:

0940 CDT

Type of Airspace:

 

 

Airport Information

Airport:

Chicago O'Hare IAP (ORD)

Runway Surface Type:

Asphalt; Concrete

Airport Elevation:

672 ft

Runway Surface Condition:

Unknown

Runway Used:

14R

IFR Approach:

Unknown

Runway Length/Width:

9685 ft / 200 ft

VFR Approach/Landing:

Precautionary Landing

 

Wreckage and Impact Information

Crew Injuries:

6 None

Aircraft Damage:

Minor

Passenger Injuries:

134 None

Aircraft Fire:

None

Ground Injuries:

N/A

Aircraft Explosion:

None

Total Injuries:

140 None

Latitude, Longitude:

43.041667, -89.350278 (est)

 


 


Administrative Information

Investigator In Charge (IIC):

Edward F Malinowski

Report Date:

11/07/2012

Additional Participating Persons:

Robert Hendrickson; Federal Aviation Administration; Washington, DC

David McNair; Transportation Safety Board of Canada; Gatineau, QB, Canada,  

Stirling Macfarlane; PPG Industries, Inc.; Huntsville, AL

Alain Agnesetti; French Bureau d' Enquetes et d'Analyses (BEA); Paris, France,

Publish Date:

11/07/2012

Investigation Docket:

http://dms.ntsb.gov/pubdms/search/dockList.cfm?mKey=81818