EC-135P2 Compressors stall

[CWGOH]

I have an experience on 2/1/14 while taxying out, experienced a series of loud noise and shaking. Then it stop suddenly within spilt seconds. taxy back and examine the engine where the covers shows sign of back pressure bulged. Time 10.15am in WMSA, wind light and variable at 30 deg Celcius. Just refuelled full with addition of 215Kg Jet A1. Total load of 2673Kg hovering at 63% torque and 80% indicated power. All checks shows the EC-135 to be normal except for the mass moment was exceeded as the violent shaking could have induced an abnormal forces. Fuel before and after occurrence found to be normal. Would like to know what causes it and how to prevent it happening again. Taxying straight and level. 2 Pilots in front and one pax at rear. Please give any comments relevant to EC-135P2 experience.
Thanks
cwgoh

[skadi]

How is the condition of the compressorblades? The P&W are sensitive when operated in dirty conditions without inlet barrier filters. Do a powercheck and check the results.

skadi

[Thomas coupling]

I wouldn't fly it until the compressors are checked with a camera at the very least. You really don't know what happened there and are risking a lot if you go flying, especially now you have advertised it to joe public - the insurance company would not cover you.

[Shawn Coyle]

One engine or both? Into wind or downwind? ECU download?

[handysnaks]

Have been operating aircraft fitted with P&W 206/7 since 1999 (MD 902/EC 135). They have been pretty bulletproof, not heard of any previous compressor stall events. We try and comp rinse daily. I'd have a qualified adult check it out were it one of ours!