Narrative:

We were inbound to ZZZ cruising at FL190. We had a left intake light that came on several times; followed by a rollback on the left engine. I was the PF but xferred control to the first officer so I could communicate with maintenance on communication #2. During this time; center told us to descend to 9000 ft. I was talking with maintenance and forgot to set my altimeter to a local setting descending below FL180. My first officer forgot as well. After talking with maintenance; I resumed my role as PF. The first officer began the descent checklist. Center switched us to approach while the first officer was still getting the ATIS. I checked on with approach just as we were leveling at 9000 ft. When checking on; I told approach we were leveling at 9000 ft but didn't yet have the current ATIS. She replied with a current altimeter of 29.61. As I put in the new altimeter; I realized we had never reset the altimeters from 29.92 and with the current local setting we were approximately 300 ft below our assigned altitude. ATC did not say anything about noticing the deviation and I corrected to 9000 ft with the current setting. I was distraction talking with maintenance during descent and forgot to reset the altimeter. Because the first officer was assigned PF duties he did not begin the descent check as early as normal; delaying getting a current setting that might have helped us catch our error. In addition; ATC never gave us a local altimeter setting when they issued the descent clearance.

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Original NASA ASRS Text

Title: AN SF340 FLT CREW FLEW THROUGH THEIR ASSIGNED ALT IN DESCENT WHEN THEY FAILED TO RESET THEIR ALTIMETERS; IN PART BECAUSE THEY WERE DISTRACTED BY A MINOR ENG PROBLEM.

Narrative: WE WERE INBOUND TO ZZZ CRUISING AT FL190. WE HAD A L INTAKE LIGHT THAT CAME ON SEVERAL TIMES; FOLLOWED BY A ROLLBACK ON THE L ENG. I WAS THE PF BUT XFERRED CTL TO THE FO SO I COULD COMMUNICATE WITH MAINT ON COM #2. DURING THIS TIME; CTR TOLD US TO DSND TO 9000 FT. I WAS TALKING WITH MAINT AND FORGOT TO SET MY ALTIMETER TO A LCL SETTING DSNDING BELOW FL180. MY FO FORGOT AS WELL. AFTER TALKING WITH MAINT; I RESUMED MY ROLE AS PF. THE FO BEGAN THE DSCNT CHKLIST. CTR SWITCHED US TO APCH WHILE THE FO WAS STILL GETTING THE ATIS. I CHKED ON WITH APCH JUST AS WE WERE LEVELING AT 9000 FT. WHEN CHKING ON; I TOLD APCH WE WERE LEVELING AT 9000 FT BUT DIDN'T YET HAVE THE CURRENT ATIS. SHE REPLIED WITH A CURRENT ALTIMETER OF 29.61. AS I PUT IN THE NEW ALTIMETER; I REALIZED WE HAD NEVER RESET THE ALTIMETERS FROM 29.92 AND WITH THE CURRENT LCL SETTING WE WERE APPROX 300 FT BELOW OUR ASSIGNED ALT. ATC DID NOT SAY ANYTHING ABOUT NOTICING THE DEV AND I CORRECTED TO 9000 FT WITH THE CURRENT SETTING. I WAS DISTR TALKING WITH MAINT DURING DSCNT AND FORGOT TO RESET THE ALTIMETER. BECAUSE THE FO WAS ASSIGNED PF DUTIES HE DID NOT BEGIN THE DSCNT CHK AS EARLY AS NORMAL; DELAYING GETTING A CURRENT SETTING THAT MIGHT HAVE HELPED US CATCH OUR ERROR. IN ADDITION; ATC NEVER GAVE US A LCL ALTIMETER SETTING WHEN THEY ISSUED THE DSCNT CLRNC.

Data retrieved from NASA's ASRS site as of May 2009 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.