ASN Wikibase Occurrence # 278973
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Sunday 10 February 2019 |
| Time: | 17:00 LT |
| Type: |  Lancair IV |
| Owner/operator: | |
| Registration: | N549CJ |
| MSN: | 218 |
| Year of manufacture: | 2014 |
| Total airframe hrs: | 307 hours |
| Engine model: | Continental TSIO-550-E |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Laramie, Wyoming -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Casper/Natrona County International Airport, WY (CPR/KCPR) |
| Denver, CO (FTG) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The pilot reported that, during cruise flight at 15,500 feet mean sea level in the pressurized airplane, he heard a loud 'bang†as the windscreen fractured. The pilot diverted to a nearby airport, where he landed the airplane uneventfully.
An examination of the windshield pieces revealed that the fracture origin area displayed features consistent with a preexisting crack that developed due to environmental stress cracking (ESC). ESC is a fracture mechanism in polymer materials that occurs when a susceptible polymer material is exposed to a combination of tensile stress and exposure to a substance that degrades the integrity of the material. The ESC was likely a result of contact with a degrading substance, the origin of which could not be determined.
Although a stress analysis of the windscreen structure was not completed, the location of the fracture origin was likely an area of high stress on the windscreen due to the curvature at that location. Sustained high stress in acrylic can promote crack development, particularly when the acrylic is also exposed to certain chemical agents. The overall appearance of the windscreen edge showed limited visual evidence of adhesive on the surface, suggesting a relatively low bond strength between the windscreen at the frame. Evidence of voids in the epoxy at the interior bond surface were observed; if portions of the windscreen became disbonded, this could have affected the stress state of the windscreen and contributed to increased stress at the fracture origin area.
Probable Cause: An environmental stress cracking failure of the acrylic windshield, which resulted in a rapid decompression during cruise flight.
Accident investigation:
 |
|
Sources:
NTSB WPR19LA088
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 05-Jun-2022 14:06 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation