Dear all,

After a recent GT MI on our frame V MS5001 NP gas turbine, a lube oil leaking issue has developed near the 2nd bearing inside the heat shield.

Initially, it was discovered since there are thick oil mist coating on the UV detectors. By tracing the oil mist stain left in the enclosure, we locked the source of leaking at the 2nd bearing behind the heat shield.

After some investigation, we found that during the major inspection, no Loctite was applied on the oil baffle and all the bearing guard/covers (I am not a mechanical guy). As a result, we opened the bearing No. 2 top cover without opening the exhaust plenum. we cleaned the surface, applied Loctite 510 and did re-tourquing on all of the bolts. However, we did not touch the oil baffle (which was not changed during the GT MI).

2 weeks later, the metal rim above the heat shield developed some visible black burn marks. After checking the bearing cover behind the heat shield, small pool fire was observed. The flame is continuous and had to be put out twice after the GT shutdown.

Our plan now is to open up the roof/exhaust plenum top cover, the 2nd bearing assembly to estimate the damage caused. At the same time, we are planning to change the 2nd bearing oil baffle as well. However, we are not sure about the exact cause of the leakage/fire.

I would like to seek your expertise in determining the cause of the leakage. At the same time, are there any other parts which we have overlooked? What's the worst possible damage can be caused by the fire (at least 2 weeks, since the flame is small and hidden behind the heat shield, it was not captured by the UV detectors). Really appreciate your input, if additional information is required, I will be more than happy to provide the details. Thank you again for reading this thread.

Best Regards,
Dawei

 

dear dawei

we have also ms50001 machine. we too faced same problem. after detail investigation we find that mist eliminator's filter was chocked. choked filter causes no sufficient negative pressure in Lube oil tank leads to pressurization in tank. mist eliminator used to collect mist from LO tank by sucking it. so positive press in tank causes oil leaks from BRG.2 area & leads to fire.

suggestion :keep two mist eliminators parallel one main & other standby

regards
RR

 

Dear Sir,

There are some issues:
the Oil baffle was not replaced during major inspection (why not?)
Gasket was not applied before to close the housing bearing (initially)

The oil baffle could be damaged (bent) during the application gasket work. It's some uncomfortable try to pull up the upper housing bearing without remove the exhaust casing.

The gasket (loctite 510) was cured properly?

During MI, was performed a contact surface test between upper and lower housing bearing?


Have you identified the exactly side of the leak?

When the leak occurs?

the cause of the fire is oil and heat i guess. You shuld verify the orifice plate in air seal line and vent line.