Mar 23, 2022Liked by Chris J. Karr, David Thornton
I enjoy your aircraft articles. I've always been doubtful of aircraft structural integrity. My structural experience is in heavy steel and concrete, so I always got a little queasy when looking out the window of a corporate King Air and seeing the fine cracks radiating from wing rivets. The cracking was stopped by tiny holes drilled at the end of the cracks. I understand how stress relief works but my guiding principals were that there is no excuse for tension failures and when in doubt make it stout. If I designed an airplane, it would require Saturn rockets to get off the ground.
I once had a structural engineering Ph.D. assigned to my group who was laid off at Lockheed when most of their government contracts ended. He told me that the safety factor in aircraft structures were sometimes barely 1 instead of the higher numbers I was used to. He knew I hated flying, but I don't believe he was kidding.
Mar 23, 2022·edited Mar 23, 2022Liked by David Thornton
I always love hearing your insights and expertise when it comes to aviation, given your experiences as a pilot. Pilots are some of the most rational and level headed people I've know, and that I can see that in your thoughtful and insightful political punditry as well.
When you mentioned in-flight structural failure, the first things that come to mind are Japan Air Lines 123, and China Airlines 611. Both were 747-200s, and both jets had tail strike incidents 7 and 22 years before their accidents, respectively. The Japan Airlines flight had damaged the rear pressure bulkhead, which Boeing technicians installation of a splice place didn't comply with Boeing's repair procedures. And in China Airlines, they had a tail strike in 1980 when landing, which damaged the skin. Their tech ops didn't cut out the damaged skin and just threw on a doubler patch that didn't even cover all the damaged areas, which would later spread into cracks. In Japan Airlines 7 years later, structural failure of the rear pressure bulkhead resulted in a explosive decompression, and blew off most of the tail fin. But what made the airplane uncontrollable, was that all of its hydraulic lines were cut with subsequent total hydraulic failure. These pilots spent the next 30 minutes desperately trying to control the jet through the thrust levers. Eventually, they crashed into a mountain near Fuji, and 520 souls were killed. In China Airlines, the cracks developed and spread over time from repeated pressurization/depressurization, and eventually broke apart at cruising altitude. In both cases, improper repair and maintenance cost a total of 745 lives.
I think when it comes to commercial aviation, safety of course is paramount. But what is unavoidable, is that the design of the aircraft also has to consider economics of operation in mind as well. So there will inevitably be tradeoffs in performance, economics, and safety during the design phase, which has to be mitigated in careful compromises among the demands required by each of these criterion and others. The challenge for any commercial aircraft manufacturer is to find the sweet spot that doesn't unduly compromise the safety and airworthiness of the aircraft, yet delivers sufficient levels of performance and economics to where it is commercially viable. The 737 NG has proven to be a very safe and reliable model, and I think they will get to the bottom of it sooner or later. It's great that they already found the FDR, and will eventually find the CVR. I think we'll sooner or later find out the cause of this China Eastern accident. So much easier than when an aircraft crashes into the ocean, and trying to find the black boxes and other crucial debris on the ocean floor. I still hope someday, they can eventually crack the mystery of Malaysia Airlines 370.
That truck the guy was driving looks like an early 2000s Chevy Silverado. I remember back in those days the "Like A Rock" TV commercials bragging how rugged their trucks are. What better way to show that your product is tough as a rock then when it gets tossed about by a tornado, and still drives away from it this intact? GM ought to give this guy a free replacement pickup, and brag about how a twister can't even stop one of their trucks in an upcoming ad.
I enjoy your aircraft articles. I've always been doubtful of aircraft structural integrity. My structural experience is in heavy steel and concrete, so I always got a little queasy when looking out the window of a corporate King Air and seeing the fine cracks radiating from wing rivets. The cracking was stopped by tiny holes drilled at the end of the cracks. I understand how stress relief works but my guiding principals were that there is no excuse for tension failures and when in doubt make it stout. If I designed an airplane, it would require Saturn rockets to get off the ground.
I once had a structural engineering Ph.D. assigned to my group who was laid off at Lockheed when most of their government contracts ended. He told me that the safety factor in aircraft structures were sometimes barely 1 instead of the higher numbers I was used to. He knew I hated flying, but I don't believe he was kidding.
I always love hearing your insights and expertise when it comes to aviation, given your experiences as a pilot. Pilots are some of the most rational and level headed people I've know, and that I can see that in your thoughtful and insightful political punditry as well.
When you mentioned in-flight structural failure, the first things that come to mind are Japan Air Lines 123, and China Airlines 611. Both were 747-200s, and both jets had tail strike incidents 7 and 22 years before their accidents, respectively. The Japan Airlines flight had damaged the rear pressure bulkhead, which Boeing technicians installation of a splice place didn't comply with Boeing's repair procedures. And in China Airlines, they had a tail strike in 1980 when landing, which damaged the skin. Their tech ops didn't cut out the damaged skin and just threw on a doubler patch that didn't even cover all the damaged areas, which would later spread into cracks. In Japan Airlines 7 years later, structural failure of the rear pressure bulkhead resulted in a explosive decompression, and blew off most of the tail fin. But what made the airplane uncontrollable, was that all of its hydraulic lines were cut with subsequent total hydraulic failure. These pilots spent the next 30 minutes desperately trying to control the jet through the thrust levers. Eventually, they crashed into a mountain near Fuji, and 520 souls were killed. In China Airlines, the cracks developed and spread over time from repeated pressurization/depressurization, and eventually broke apart at cruising altitude. In both cases, improper repair and maintenance cost a total of 745 lives.
I think when it comes to commercial aviation, safety of course is paramount. But what is unavoidable, is that the design of the aircraft also has to consider economics of operation in mind as well. So there will inevitably be tradeoffs in performance, economics, and safety during the design phase, which has to be mitigated in careful compromises among the demands required by each of these criterion and others. The challenge for any commercial aircraft manufacturer is to find the sweet spot that doesn't unduly compromise the safety and airworthiness of the aircraft, yet delivers sufficient levels of performance and economics to where it is commercially viable. The 737 NG has proven to be a very safe and reliable model, and I think they will get to the bottom of it sooner or later. It's great that they already found the FDR, and will eventually find the CVR. I think we'll sooner or later find out the cause of this China Eastern accident. So much easier than when an aircraft crashes into the ocean, and trying to find the black boxes and other crucial debris on the ocean floor. I still hope someday, they can eventually crack the mystery of Malaysia Airlines 370.
That truck the guy was driving looks like an early 2000s Chevy Silverado. I remember back in those days the "Like A Rock" TV commercials bragging how rugged their trucks are. What better way to show that your product is tough as a rock then when it gets tossed about by a tornado, and still drives away from it this intact? GM ought to give this guy a free replacement pickup, and brag about how a twister can't even stop one of their trucks in an upcoming ad.