CASE STUDY: CAUSE OF AIRCRAFT WINDSHIELD FAILURE

BACKGROUND

The pilot of the aircraft reported that there had been a failure of the interior lamination of the left-hand windshield of a commercial aircraft at 27,000′. Trident was asked to determine the cause of the crack damage.

The obvious damage to the windshield is a densely cracked (diced) failure of the interior glass lamination originating near the top centerline corner of the windshield. The photograph below provides an overall view of the left-hand windshield.

Exterior view of the left hand (pilot’s) windshield. The red arrow indicates the area of the origin of the crack failure.
 
A close up exterior view of the top centerline corner of the left-hand windshield. Note how the crack pattern expanded outward from the area of the origin. A segment of the black plastic hump (edge) seal has been removed to facilitate the microscopic search for the origin.
Closeup interior view of the top centerline cornerof the left-hand windshield.The red arrow indicates the origin of the crack failure. This photograph also shows how the crack pattern expanded outward from the origin.
 
Microscopic (15x) interior view of the origin of the overall crack failure of the interior lamination of the windshield. This image has been back-lighted to show the details of the peel chip.

CONCLUSION

Trident Engineering Associates, Inc. concludes to a reasonable degree of engineering certainty that:

a. The cause of failure of the interior (innermost) glass lamination of the left hand (pilot’s) windshield was internal stresses which were concentrated at the top centerline corner of the windshield. The internal stresses caused a peel chip to form in the interior lamination of the windshield.

b. The overall crack failure of the windshield originated at the peel chip at the top
centerline corner. Subsequent stress-relieving resulted in the densely cracked failure of the tempered glass interior lamination.

c. There is no indication of foreign object damage to the outer surface of the windshield
as a cause of the failure, particularly since it is the interior lamination that has failed.

Trident’s analysis will allow Trident’s client to submit a claim against the manufacturer (or installer) of this windshield, which has a value of around $40,000.

EXPERTS

  • Stanley “Sandy” J. Dapkunas, P.E.
    Director of Aviation & Marine Engineering
  • Timothy R. Geis, P.E.
  • Thomas Nodeen
  • Karen Wiley-Alt
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