FOD Caused Cracked Windshields
On February 16, numerous freak incidents of cracked aircraft windshields at Denver International Airport were reported. The cracked windshields were on 14 aircraft of various aircraft type operated by three different carriers. Six aircraft experienced the cracking during takeoff, another just after landing, two upon taxiing to the terminal after landing, and three while they were sitting at their gates. Wind speeds that day were gusting up to 48 miles per hour.
I have to imagine that all those cracked windshields caused many engineers and mechanics to scratch their heads as they tried to figure out the cause.
The NTSB still hasn’t issued a final report on the incidents, but Denver-based NTSB investigator Jennifer Kaiser, who led the probe into these incidents, has commented on the likely cause of the cracks.
A February 28 article in the Denver Post by Jeffrey Leib says that Kaiser attributes the damage to FOD.
So, what kind of FOD is Kaiser talking about? Hail? Hardware on the ramp thrown into the windows? Bird strikes? Rocks?
None of the above. Believe it or not, it was sand. In the article, Kaiser says it is possible that sand that was put down on the airport’s runways and taxiways during December and January snow storms were blown into the windshields that windy February day. Microscopic analysis of the windows showed that fine particles caused pitting in the windows. The pitting in turn caused the cracking.
So, case solved? Maybe not. Investigators were not able to determine with certainty what debris caused the damage because there were no transfer marks from the material onto the windshields.
It is hard to imagine that blowing sand can cause aircraft windshields to crack. If it can, I am curious — how were all the other aircraft that were at the airport that day affected by the sand? Were they also damaged by the sand FOD? Will that damage eventually lead to more freak incidents of cracked windshields?
You can click here to read the full Denver Post article.
Thanks for reading.
Joe
Sand? What about all the aircraft that are in the Middle East and other areas that have very sandy conditions?
Micro cracking I understand, stress risers, I understand. How can multi layer windshilds have problems I don’t inderstand.
I think it’s way too early to state a probable cause. The other similar factor between all of these airplanes is weather–extreme cold, and although the airplanes are different types, the windshield/windows are made pretty much in the same manner…will be interesting to see the final report. Is there a link to more information? what type aircraft, where the planes were going, how long they had been parked, etc.?
Meteorites!
I was the maintenance supervisor for forty KC-135 Stratotankers during the first Gulf War. Sand blew around the airport north of Riyad, Saudi Arabia like the snows of Northern Michigan. We never had a windshield crack because of sand. It would scour the glass and we would have to change it because of visibility problems.
I’ve personally seen the effects of high winds and debris on windshields. I was working on a twin otter in Alaska and had a windshield damaged in a windstorm. The winds were blowing at least 75 mph and there were reports of blowing gravel. The copilots windshield developed several cracks. The windshield was had tiny pits in it but no large ones like you would suspect from rocks or other debris. The wind also broke a landing light lens which on the twin otter is pretty high off the ground. one other operator had their Navajo winshield damaged too. Id believe gravel and not sand as the cause.
I’ve been in the aviation industry for 22 years i think the problem exsisited due to the coeificent of expansion and contraction of the window post. stress risers are created by the improper torque sequence of the windows and the contraction of the window post caused the stress to rise at the windows due to the different contractions of the window post and caused the cracking.
even if operators and aircraft are not the same what about MRO?
I think I would be looking at some engine compressors too.
Airports should clean up there sand, if they have to use it.
[…] This past February, a mysterious event occurred at the DIA. Cracks appeared on the windshields of over a dozen aircraft that were flying, taxing, or parked at the terminal. Government officials claimed that it was caused by blowing sand, but some in the industry disagree that sand can cause such extensive damage to aircraft windshields. For some, the cracked windshields, like many of the other features of the DIA, are a mystery. […]