tag:blogger.com,1999:blog-1592992209402300549.post787441972319143908..comments2024-03-28T08:06:43.198-04:00Comments on The Silicon Graybeard: The Biggest Story That Didn't Make the NewsSiGraybeardhttp://www.blogger.com/profile/00280583031339062059noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-1592992209402300549.post-57477885288025861142016-08-08T16:09:53.024-04:002016-08-08T16:09:53.024-04:00http://www.cashill.com/twa800/
The evidence refut...http://www.cashill.com/twa800/<br /><br />The evidence refutes the fuel tank claim.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-5175632313705187072016-08-07T11:41:14.143-04:002016-08-07T11:41:14.143-04:00I just haven't thought about that hardly at al...I just haven't thought about that hardly at all. I suppose my opinion is that I see no reason to doubt the NTSB and the official story. You can rightly conclude that means I haven't really paid much attention to the story. It appears to be a horrific failure, but it's out of my area of expertise. <br /><br />In general, airplanes don't just explode, but a one-in-a-million failure, or a cascade of two, is always possible. Improbable things happen all the time. The number of 747s and their flight hours is so low compared to the kind of total flight hour numbers I was talking about above that they may have never gotten to the point of seeing a one in a million or one in ten million failure. <br /><br />A point I didn't emphasize in this piece is the saying that the FAA regulations are written in blood. For example, take those seats rated to survive 16G impacts. They're that strong now because analysis of a terrible crash on the ground showed people died because the previous designs weren't strong enough. IIRC, Flight 800 resulted in changes to the fuel system on the 747, and if they made a one in a million accident into a one in a billion accident, it's really hard to know until millions of hours of flights. <br /><br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-65718391876223249742016-08-07T10:25:59.169-04:002016-08-07T10:25:59.169-04:00What is your opinion of flight 800 and the officia...What is your opinion of flight 800 and the official investigation?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-15505830086366251392016-08-05T19:39:32.614-04:002016-08-05T19:39:32.614-04:00Dance...dance - I was never a reliability engineer...Dance...dance - I was never a reliability engineer (some places make you do a few months there as training), but I could do a few pages on it. <br /><br />The way I've seen MTBF calculated is based on a methodology from a MilSpec, MIL-HDBK-217. At some point, the failure rates for individual components are pulled out of tables and those numbers folded into a grand total. All of those failure rates are based on random failures under specific operating conditions, but components aren't necessarily used in keeping with those conditions. For example, the life of a transistor can be radically reduced by letting its junction temperature get too high. An inadequate heat sink or a change to the transistor's operating point made without changing the heat sink can happen. Those choices are made by the design guys. Resistors can fail if they get too hot, capacitors can be ruined if they're exposed to too high voltage, or too much AC ripple (if filter caps). The numbers in the MilSpec table don't mean much if the parts aren't running in the recommended conditions. <br /><br />In Major Avionics Corp, the designs were divided into functions - using block diagrams - and the failure rates computed for the blocks. The top level MTBF can be changed by different choice of the blocks and what goes in them. I have no idea if the MTBFs you're talking about were calculated this way, but it's not unusual. It could be that those systems are just well designed and the parts are being used in more gentle conditions than the tables assumed. <br /><br />Here we see one of the basic theoretical problems with reliability theory, as I see it. All of the predictions are based on random failures, but all of the improvements in reliability come from removing non-random factors. <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-81985915894495771422016-08-05T18:58:53.440-04:002016-08-05T18:58:53.440-04:00I used to be a compliance tester in an RnD departm...I used to be a compliance tester in an RnD department.<br />Since then I have found the concept of Mean Time Between Failure fascinating.<br />Moreso because where I work now most of the control systems are twenty years past their end of life date.Dance...dance to the radiohttps://www.blogger.com/profile/16688681743093469863noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-53854949000020918282016-08-05T12:43:56.589-04:002016-08-05T12:43:56.589-04:00Of course, if you ever DO get that chance, and kno...Of course, if you ever DO get that chance, and know about it at least a couple of days in advance, one could always do the sigmoidoscopy prep. Not much left in your system -at EITHER end - to depart...<br />}:-]Mark Matisnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-88458965112660744552016-08-05T11:10:35.559-04:002016-08-05T11:10:35.559-04:00I would still like to give my "kudo's&quo...I would still like to give my "kudo's" to you and the Avionics guys. Airframes are great but there are still things like system redundancy, generators, fuel shut-off valves, communications, lighting (those aisle "guiding lights" on the floor type), and probably many other things that contribute to making for a quick and successful evacuation. The "entire" team deserves recognition. Don't be shy.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-13431338059705927732016-08-05T11:01:10.166-04:002016-08-05T11:01:10.166-04:00They make some nice airplanes, for sure, but there...They make some nice airplanes, for sure, but there's a philosophical difference between the way Airbus and Boeing design things. Airbus designs their control systems with the idea being that the pilot should never be able to command the aircraft past its "envelope" (the complete range of control settings and conditions that are allowed). Boeing says the Pilot In Command is in command, and will allow the pilot to do whatever he thinks the situation requires. It's a bit subtle, but there are some historical crisis situations that make me think Boeing's approach is better. <br /><br />I'm with you on the P-51, but even more that I'd love to ride back seat on an F-18 or F-15. The Blue Angels are known to take reporters up for a backseat ride in one of their F-18s pretty regularly. It becomes a point of honor to make a guy throw up, but they're easier on the women. The way I look at it, I've thrown up before and I'll probably throw up again, but I'll never get another chance to ride in a fighter, so let's do it! <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-26094977999465398782016-08-05T10:52:45.567-04:002016-08-05T10:52:45.567-04:00Being the kind of guys we are, we naturally go one...Being the kind of guys we are, we naturally go one step farther and say the most common estimate for the number of flights in a day is 100,000. With a probability of Catastrophic event of one in a billion, that represents an average rate of one event every 10,000 days. That's once every 27 years. <br /><br />Of course, that doesn't mean in 27 years there won't be more than one and it doesn't mean there won't be none at all. <br />SiGraybeardhttps://www.blogger.com/profile/00280583031339062059noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-13980347137824978342016-08-05T09:22:28.008-04:002016-08-05T09:22:28.008-04:00As one who still works at the "Major Avionics...As one who still works at the "Major Avionics Corporation", the thing I like to remind new people is that you can't design for 100 percent safety. Instead, we design such that the probability of a "Catastrophic" event (most if not all the people die) must not exceed one in a billion. One landing in a billion landings, takeoffs, hours at cruise, and so on.<br /><br />You probably have a higher probability of having a stroke while reading this and not making it to the end. <br /><br />Good. You made it. Let's go flying!<br /> Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-7640241461402063032016-08-05T08:51:10.860-04:002016-08-05T08:51:10.860-04:00I don't fly much (since 1992) now that Uncle S...I don't fly much (since 1992) now that Uncle Sam doesn't pay for it, but in the last two years I've flown to Florida for little vacations with the wife. I get giddy and amazed like a school boy when I fly. The power, technology, and the skill involved to make flight possible is mind-numbing and incredible (and a little scary) to me, and always has been, and I don' think I could ever consider flying to be routine or mundane. This summer I took my first ride on an Airbus. What a wonderful machine! I loves me some Boeings, but the Airbus is nice.<br /><br />Oh...and I would willingly give up a body part to sit in the back seat of a P-51.Walter Zoomiehttps://www.blogger.com/profile/18439931516202804834noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-13193179918704566692016-08-05T02:10:37.651-04:002016-08-05T02:10:37.651-04:00People are spoiled.
I had an old uncle on my Mom&...People are spoiled.<br /><br />I had an old uncle on my Mom's side, and after Apollo 11 landed on the Moon, he told me about how when he was very little, his parents took him to see the Wright brothers fly.<br /><br />He said he never thought he'd live to see men walk on the Moon....drjimhttps://www.blogger.com/profile/05647484115197408897noreply@blogger.comtag:blogger.com,1999:blog-1592992209402300549.post-84487277388953478522016-08-05T01:08:30.001-04:002016-08-05T01:08:30.001-04:00Figured you might like this.
https://www.youtube....Figured you might like this.<br /><br />https://www.youtube.com/watch?v=_1ot_pGQIhwDance...dance to the radiohttps://www.blogger.com/profile/16688681743093469863noreply@blogger.com