Narrative:

During preflight I noted that the green system hydraulics were very low; almost into the yellow or amber band. I let maintenance know we needed to be serviced. He stated the level had been good when maintenance had last checked it at the termination of the previous flight. I asked when they were servicing the green system if they found any leaked hydraulic fluid; and maintenance replied in the negative. This seemed a little odd; and indicated either a possible gauge problem or a hidden leak. During descent we received an ECAM warning for low green hydraulic system fluid quantity. The overhead quantity gauge pointer was at the 'red dot.' per the ECAM we turned off the green hydraulic pumps. Due to the fact we would need some extra time on final approach to manually extend the landing gear; plus the requirement to stop on the runway and be towed in from there; we declared an emergency with ATC. After completing all related ECAM and QRH procedures; we landed uneventfully. After extending the gear; the green hydraulic quantity recovered to about the 12 o'clock position on the quantity gauge. By the time we arrived in the gate after tow-in; the quantity had dropped almost to the yellow band again. On post flight maintenance stated they found a leak in the number 1 engine pylon. Perhaps more in-depth troubleshooting during the preflight would have revealed the hydraulic leak there.

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Original NASA ASRS Text

Title: A300 Captain reports loss of Green Hydraulic System fluid during descent for landing. The fluid level had indicated low prior to departure and was serviced. An emergency is declared and a normal landing ensues after gravity gear extension.

Narrative: During preflight I noted that the green system hydraulics were very low; almost into the yellow or amber band. I let Maintenance know we needed to be serviced. He stated the level had been good when Maintenance had last checked it at the termination of the previous flight. I asked when they were servicing the green system if they found any leaked hydraulic fluid; and Maintenance replied in the negative. This seemed a little odd; and indicated either a possible gauge problem or a hidden leak. During descent we received an ECAM warning for low green hydraulic system fluid quantity. The overhead quantity gauge pointer was at the 'red dot.' Per the ECAM we turned off the green hydraulic pumps. Due to the fact we would need some extra time on final approach to manually extend the landing gear; plus the requirement to stop on the runway and be towed in from there; we declared an emergency with ATC. After completing all related ECAM and QRH procedures; we landed uneventfully. After extending the gear; the green hydraulic quantity recovered to about the 12 o'clock position on the quantity gauge. By the time we arrived in the gate after tow-in; the quantity had dropped almost to the yellow band again. On post flight Maintenance stated they found a leak in the Number 1 Engine pylon. Perhaps more in-depth troubleshooting during the preflight would have revealed the hydraulic leak there.

Data retrieved from NASA's ASRS site as of July 2013 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.