herky400M Posted October 28, 2016 Share Posted October 28, 2016 C-130 world, we are experiencing a lot of problems with the Turbine rear bearing support casing cracks. on several occasions (6) the casing is cracked near the mount clamp of the tail pipe, at the had band or between the had band and mount clamp Does any of you guy's experiencing the same issue. Does anyone have any suggestions why? AD info: turbine boroscope done no cracks on 1st stator prop is dynamically balanced no discrepancies of pilots/FE concerning special issues on the defective engine any help is welcome, meanwhile we will look into the this problem aswel. best regards Herky400M Quote Link to comment Share on other sites More sharing options...
victorp1 Posted October 28, 2016 Share Posted October 28, 2016 Has anyone marked on the casing with a lead (Pb) pencil? This normally causes a burn through on hot section metal. Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted October 28, 2016 Share Posted October 28, 2016 Are these once per turbine, or do you have repeat offenders? If repeat offenders, pull the turbine apart and check the 2nd/3rd stage rotors and the spacer discs. We had several spacers disintegrate without any indication other than the cracked support cases. We only opened the turbines because I rejected them from the test cell for out of limits vibration on the analyzer Quote Link to comment Share on other sites More sharing options...
Lkuest Posted October 29, 2016 Share Posted October 29, 2016 I agree, all you can really do is a check first stage rotor blades, balance, and a good signature check. If all those are good, you might just be having bad luck. We've gotten quite a few that crack again and again, mostly due to poor weld repairs on the replacement supports. If the signature run is good, you might try installing a known brand-new case and see if it still cracks. Of note, the rear bearing support case wasn't originally designed to mount a tailpipe, so the extra length acts as a cantilever to amplify vibrations through the weak points. The support case is Allison, and the tailpipe is Lockheed. That's why vibration is the top cause, but also explains why you might have nothing wrong with the rotating assembly and still get cracks. Quote Link to comment Share on other sites More sharing options...
herky400M Posted November 7, 2016 Author Share Posted November 7, 2016 Thx guys bob Quote Link to comment Share on other sites More sharing options...
herky400M Posted November 10, 2016 Author Share Posted November 10, 2016 To PJVR, can you tell us how many cycles the rejected spacer had and what Part number they have. To the C-130 world, any other information is very welcome, we have a 7th cracked casing thx4coop bob Quote Link to comment Share on other sites More sharing options...
NATOPS1 Posted November 10, 2016 Share Posted November 10, 2016 Same engine? Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted November 11, 2016 Share Posted November 11, 2016 22 hours ago, herky400M said: To PJVR, can you tell us how many cycles the rejected spacer had and what Part number they have. To the C-130 world, any other information is very welcome, we have a 7th cracked casing thx4coop bob Sorry Bob, no. cycles are not recorded, only flight hours. however they were well within limits. Echo NATOPS: is this same engine or turbine? Have you run this engine direct off wing on the cell? is this happening on same aircraft? what position? Quote Link to comment Share on other sites More sharing options...
herky400M Posted November 16, 2016 Author Share Posted November 16, 2016 Gents, we have 8 different engines, 3 were installed and removed on/of the aircraft only 378 FH one of the affected ones : last repair 15228 FH @ SOR (source of repair), overhauled @12298 FH ( total FH 15761 (1690,0 cycles) we are a little bit in the dark here BR bob Quote Link to comment Share on other sites More sharing options...
Moeed hassan Posted November 7, 2018 Share Posted November 7, 2018 In this case one thing is not mentioned by any one.... The most probebly cause which is overlooked by maintenence personals is the TAIL PIPE CLAMP..... the reason is when ever tail pipe is being installed on RBS many of us tried to fix tail pipe flange on RBS and some time by overtightening of this clamp excessive load felt on BOTH FLANGE and as a result cracks came on that area..... Quote Link to comment Share on other sites More sharing options...
munirabbasi Posted November 7, 2018 Share Posted November 7, 2018 On 10/28/2016 at 12:52 PM, herky400M said: C-130 world, we are experiencing a lot of problems with the Turbine rear bearing support casing cracks. on several occasions (6) the casing is cracked near the mount clamp of the tail pipe, at the had band or between the had band and mount clamp Does any of you guy's experiencing the same issue. Does anyone have any suggestions why? AD info: turbine boroscope done no cracks on 1st stator prop is dynamically balanced no discrepancies of pilots/FE concerning special issues on the defective engine any help is welcome, meanwhile we will look into the this problem aswel. best regards Herky400M Read the Lockheed Martin service news on turbine rear bearing support casing cracks. Regards Munir Abbasi Munir Abbasi Quote Link to comment Share on other sites More sharing options...
Moeed hassan Posted November 7, 2018 Share Posted November 7, 2018 12 minutes ago, munirabbasi said: Read the Lockheed Martin service news on turbine rear bearing support casing cracks. Regards Munir Abbasi Munir Abbasi What that service news says??? Quote Link to comment Share on other sites More sharing options...
Ahmer Posted November 7, 2018 Share Posted November 7, 2018 47 minutes ago, Moeed hassan said: What that service news says??? Normally turbine rear bearing support is cracked due to improper installtion procedure of tail pipe , excessive vibration of turbine(improper assembling turbine or vanes cracks), and spacers between turbine and vanes rubbing each other cause of turbine rear bearing support and tail pipe cracking. Regard Quote Link to comment Share on other sites More sharing options...
munirabbasi Posted November 8, 2018 Share Posted November 8, 2018 9 hours ago, Ahmer said: Normally turbine rear bearing support is cracked due to improper installtion procedure of tail pipe , excessive vibration of turbine(improper assembling turbine or vanes cracks), and spacers between turbine and vanes rubbing each other cause of turbine rear bearing support and tail pipe cracking. Regard See lockheed martin magazines news web page Munir abbasi Quote Link to comment Share on other sites More sharing options...
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