Garfly Posted October 13, 2022 Share Posted October 13, 2022 1 Link to comment Share on other sites More sharing options...
mkennard Posted October 13, 2022 Share Posted October 13, 2022 "This video is private". Can't watch it Link to comment Share on other sites More sharing options...
tillmanr Posted October 13, 2022 Share Posted October 13, 2022 Same for me. Link to comment Share on other sites More sharing options...
Garfly Posted October 13, 2022 Author Share Posted October 13, 2022 (edited) Sorry, it must have been taken down for some reason. It was a regular Blancolirio video. It will probably re-emerge. Here is Kathryn's Report of the same incident: http://www.kathrynsreport.com/2022/09/de-havilland-canada-dhc-3t-turbine.html And here is one pertinent comment from the Blancolirio video: Mark P 2 hours ago Good video! As a young design engineer working at a major aircraft manufacturer, I had a friend ( older and more experience than me) who was in charge of the flutter model wind tunnel testing of the YC-15. One day he stopped by my desk and suggested I follow him to go watch a video of one of their tests. As I watched the video, they incrementally increased the wind speed while sending the horizontal stabilizer a "pulse" (literally pull a string that was attached to it) simulating a gust or other similar disturbance. Finally at one critical speed, the tail failed almost instantly. I couldn't actually see the flutter because it happened so quickly. When he re-ran the video in slow motion, we saw the pulse deflect the stab upward, and then it cycled down and up for about 2 or 3 diverging cycles, and then failed completely. Absolutely NO chance for pilot intervention. The results of this test had already resulted in design changes to stiffen the tail, so the first vehicle rolled out with the stronger tail already in place. That moment was one that will remain in memory and it gave me great respect for flutter for the remainder of my 43 year design career. Edited October 13, 2022 by Garfly 1 Link to comment Share on other sites More sharing options...
Garfly Posted October 13, 2022 Author Share Posted October 13, 2022 (edited) FAA Emergency AD: https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID139391948320221005002535.0001 EXCERPT [click for full rez] : FAA Under Scrutiny for Timing of DHC-3 AD Transport Canada issued a similar airworthiness directive more than four years ago. https://www.flyingmag.com/faa-under-scrutiny-for-timing-of-dhc-3-ad/ Edited October 13, 2022 by Garfly Link to comment Share on other sites More sharing options...
facthunter Posted October 14, 2022 Share Posted October 14, 2022 Flutter is bad news. Most times it happens quickly and nothing can be done. Nev Link to comment Share on other sites More sharing options...
Garfly Posted October 14, 2022 Author Share Posted October 14, 2022 Here is the re-posting of the original video by Blancolirio: 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 14, 2022 Share Posted October 14, 2022 Salt environment and vibration. Aluminium doesn't like it. The Otter dates back to the 50's. Nev 1 Link to comment Share on other sites More sharing options...
Student Pilot Posted October 14, 2022 Share Posted October 14, 2022 Otter is a good machine, designed with the 1340 radial. The turbine pulls harder and flys faster than the radial ever did, this creates problems the designers didn't allow for. 3 Link to comment Share on other sites More sharing options...
APenNameAndThatA Posted October 14, 2022 Share Posted October 14, 2022 16 minutes ago, Student Pilot said: Otter is a good machine, designed with the 1340 radial. The turbine pulls harder and flys faster than the radial ever did, this creates problems the designers didn't allow for. Flutter occurs because of excessive airspeed (actual airspeed, not indicated airspeed). I could not work out how an established, old, slow design could get flutter. Looks like I just found out. 2 Link to comment Share on other sites More sharing options...
Thruster88 Posted October 14, 2022 Share Posted October 14, 2022 Flutter also occurs when things get loose, working rivets, cracked parts or worn control rods etc. The Vne on the turbine conversion DHC-3 was reduced from 180? to about 140knots because of earlier issues. The accident aircraft was not speeding. 3 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 14, 2022 Share Posted October 14, 2022 Some of that Maintenance is terrible The structure has to remain firm and connections playless. Propwash causes vibrations too.. Do they use BETA? Nev Link to comment Share on other sites More sharing options...
Student Pilot Posted October 14, 2022 Share Posted October 14, 2022 13 hours ago, facthunter said: Some of that Maintenance is terrible The structure has to remain firm and connections playless. Propwash causes vibrations too.. Do they use BETA? Nev Depends on the engine fitted, Pratts yes, Garret not as much but still yes. Link to comment Share on other sites More sharing options...
Student Pilot Posted October 14, 2022 Share Posted October 14, 2022 14 hours ago, Thruster88 said: Flutter also occurs when things get loose, working rivets, cracked parts or worn control rods etc. The Vne on the turbine conversion DHC-3 was reduced from 180? to about 140knots because of earlier issues. The accident aircraft was not speeding. Having a lower VNE doesn't mean they will stick to it. The Drom conversions in Oz had a low VNE anyway but didn't stop people from flying around way beyond VNE. 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 14, 2022 Share Posted October 14, 2022 Obviously they don't know the meaning of NEVER exceed.. I do and it might be one of the reasons I'm still here.. Nev 4 1 Link to comment Share on other sites More sharing options...
Student Pilot Posted October 15, 2022 Share Posted October 15, 2022 I am always wary towards VNE..... 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 25, 2022 Share Posted October 25, 2022 Anyhow bad Maintenance throws the book figure away. it's always LOWER than the original published one. Nev 1 Link to comment Share on other sites More sharing options...
Garfly Posted October 25, 2022 Author Share Posted October 25, 2022 Today's update: 2 Link to comment Share on other sites More sharing options...
Garfly Posted October 25, 2022 Author Share Posted October 25, 2022 (edited) On 14/10/2022 at 5:48 PM, Thruster88 said: Flutter also occurs when things get loose, working rivets, cracked parts or worn control rods etc. The Vne on the turbine conversion DHC-3 was reduced from 180? to about 140knots because of earlier issues. The accident aircraft was not speeding. Looks like our Thruster88 might have been barking up the right tree! Edited October 25, 2022 by Garfly 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 25, 2022 Share Posted October 25, 2022 They had no hope at all. That clip is inadequate as a lock feature. This all operates in a salt and ice environment. Be alert to any resistance or change of feel in any trim or control. Nev 2 1 Link to comment Share on other sites More sharing options...
Thruster88 Posted October 25, 2022 Share Posted October 25, 2022 Having an external wire clip securing the vital clamp nut seems less than ideal. 1 Link to comment Share on other sites More sharing options...
facthunter Posted October 29, 2022 Share Posted October 29, 2022 They have specified a mandatory inspection for the clip installation but it's still a lousy arrangement. No clip was found at the accident site. Nev Link to comment Share on other sites More sharing options...
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