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herky400M

Turbine rear bearing support casing cracks

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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:

  1. turbine boroscope done no cracks on 1st stator
  2. prop is dynamically balanced
  3. 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

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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

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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.

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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  :unsure:

 

thx4coop bob

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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  :unsure:

 

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?

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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

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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.....

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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:

  1. turbine boroscope done no cracks on 1st stator
  2. prop is dynamically balanced
  3. 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 

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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??? 

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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 

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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 

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