Narrative:

XA00Z, 134.3, ZSU. Location: grann 50 NM south. Climbing out of sju at 16000 ft, we turned on the engine anti-ice and at the same time we were deviating around WX near the vermo intersection. At FL220 we started to encounter light icing and then at FL250 encountered moderate rime icing which was sustained all the way to FL340. Passing FL265 we noticed the left engine vibration monitor was at 3.4 N1 and we then went to the abnormal procedure in volume 1 and followed the engine vibration procedure when we leveled at FL350 clear of clouds. The book says if in icing conditions the fan should normally shed ice. Well, it wasn't, so the procedure called for us to assist in the shedding of the ice and followed the procedure by retarding the left throttle to idle for 5 seconds then bringing it back to 90 percent N1. That was completed and the vibration N1 was at 3.2 N1 after the procedure was completed and we felt some shedding of ice. The N1 vibration continued to increase all the way to 5.0 N1 and I repeated the procedure to assist in removing the remaining ice on the fan blades. Upon pushing the left throttle towards 90% N1, a series of compressor stalls occurred at FL350 and at approximately between 75-80% N1, no exceedance of egt was observed. As a result of the compressor, I elected to descend to FL280 and retarded the left throttle to eliminate the vibration and made the decision to divert to bda. The left engine operated fine at idle with N1 vibration not in amber, therefore we left the engine running in anticipation of the ice melting at lower altitudes. The cruise and descent was uneventful and the landing was made at 195000 pounds. The left engine operated normally at low altitudes and the vibration monitor was at 1.4 N1 with a fuel flow of 4500 pounds per engine -- no noticeable vibration observed. Upon parking the aircraft at bda the mechanics noticed the turbine blades were wet and the oil quantity on the left engine was 16 quarts on shutdown and we left sju with 19 quarts on departure. I suspect that the compressor stall possibly caused a rupture in a turbine seal and resulted in the oil leaking. Another bit of information. When the compressor stall was occurring, an acrid oil like odor was noticed throughout the aircraft. Once the left throttle was retarded, the odor and vibration ceased. I did not elect to go into sju because the WX was the cause of this problem and was not suitable due to WX conditions at sju airport. I feel I made the right decision to go to bda due WX in sju wasn't accurately forecast. Also, no mention of moderate icing condition were ever SIGMET'ed to us in our flight plan release.

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Original NASA ASRS Text

Title: A B757 FLT ENRTE FROM SJU ENCOUNTERS INFLT ICING. FLT DIVERTS TO BDA AFTER SEVERAL COMPRESSOR STALLS AND ENG VIBRATION INDICATIONS ON #1 ENG.

Narrative: XA00Z, 134.3, ZSU. LOCATION: GRANN 50 NM S. CLBING OUT OF SJU AT 16000 FT, WE TURNED ON THE ENG ANTI-ICE AND AT THE SAME TIME WE WERE DEVIATING AROUND WX NEAR THE VERMO INTXN. AT FL220 WE STARTED TO ENCOUNTER LIGHT ICING AND THEN AT FL250 ENCOUNTERED MODERATE RIME ICING WHICH WAS SUSTAINED ALL THE WAY TO FL340. PASSING FL265 WE NOTICED THE L ENG VIBRATION MONITOR WAS AT 3.4 N1 AND WE THEN WENT TO THE ABNORMAL PROC IN VOLUME 1 AND FOLLOWED THE ENG VIBRATION PROC WHEN WE LEVELED AT FL350 CLR OF CLOUDS. THE BOOK SAYS IF IN ICING CONDITIONS THE FAN SHOULD NORMALLY SHED ICE. WELL, IT WASN'T, SO THE PROC CALLED FOR US TO ASSIST IN THE SHEDDING OF THE ICE AND FOLLOWED THE PROC BY RETARDING THE L THROTTLE TO IDLE FOR 5 SECONDS THEN BRINGING IT BACK TO 90 PERCENT N1. THAT WAS COMPLETED AND THE VIBRATION N1 WAS AT 3.2 N1 AFTER THE PROC WAS COMPLETED AND WE FELT SOME SHEDDING OF ICE. THE N1 VIBRATION CONTINUED TO INCREASE ALL THE WAY TO 5.0 N1 AND I REPEATED THE PROC TO ASSIST IN REMOVING THE REMAINING ICE ON THE FAN BLADES. UPON PUSHING THE L THROTTLE TOWARDS 90% N1, A SERIES OF COMPRESSOR STALLS OCCURRED AT FL350 AND AT APPROX BTWN 75-80% N1, NO EXCEEDANCE OF EGT WAS OBSERVED. AS A RESULT OF THE COMPRESSOR, I ELECTED TO DSND TO FL280 AND RETARDED THE L THROTTLE TO ELIMINATE THE VIBRATION AND MADE THE DECISION TO DIVERT TO BDA. THE L ENG OPERATED FINE AT IDLE WITH N1 VIBRATION NOT IN AMBER, THEREFORE WE LEFT THE ENG RUNNING IN ANTICIPATION OF THE ICE MELTING AT LOWER ALTS. THE CRUISE AND DSCNT WAS UNEVENTFUL AND THE LNDG WAS MADE AT 195000 LBS. THE L ENG OPERATED NORMALLY AT LOW ALTS AND THE VIBRATION MONITOR WAS AT 1.4 N1 WITH A FUEL FLOW OF 4500 LBS PER ENG -- NO NOTICEABLE VIBRATION OBSERVED. UPON PARKING THE ACFT AT BDA THE MECHS NOTICED THE TURBINE BLADES WERE WET AND THE OIL QUANTITY ON THE L ENG WAS 16 QUARTS ON SHUTDOWN AND WE LEFT SJU WITH 19 QUARTS ON DEP. I SUSPECT THAT THE COMPRESSOR STALL POSSIBLY CAUSED A RUPTURE IN A TURBINE SEAL AND RESULTED IN THE OIL LEAKING. ANOTHER BIT OF INFO. WHEN THE COMPRESSOR STALL WAS OCCURRING, AN ACRID OIL LIKE ODOR WAS NOTICED THROUGHOUT THE ACFT. ONCE THE L THROTTLE WAS RETARDED, THE ODOR AND VIBRATION CEASED. I DID NOT ELECT TO GO INTO SJU BECAUSE THE WX WAS THE CAUSE OF THIS PROB AND WAS NOT SUITABLE DUE TO WX CONDITIONS AT SJU ARPT. I FEEL I MADE THE RIGHT DECISION TO GO TO BDA DUE WX IN SJU WASN'T ACCURATELY FORECAST. ALSO, NO MENTION OF MODERATE ICING CONDITION WERE EVER SIGMET'ED TO US IN OUR FLT PLAN RELEASE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.