Narrative:

I accepted the aircraft for two flights. While at the first destination it was noticed that the hydraulic quantity on the a system was lower than normal; but well within operating limitations. We checked for possible fluid leaks and I noted this information and flew to the second destination. Upon arrival; there was a slight reduction in the quantity of hydraulic fluid in the a side which prompted us to call our maintenance department. We were advised to monitor the quantity and that the aircraft would be serviced upon completion of our next day of flying. We departed the next morning to position for the passenger leg. Before we departed we made sure to check hydraulic quantities of both systems and inspected for possible leaks. The quantity had not changed from the previous inspection. Upon arrival in at the first destination; we noticed that the quantity of hydraulic fluid had again decreased; but only slightly and still well within operating limitations. We departed for a long flight to our second destination and upon reaching the cruise phase we noticed that the quantity had now decreased by about 10-15%; but was still within operating limitations. At this point we decided to monitor any further fluid loss. The fluid remained at the same level for over an hour before decreasing by 1%. We determined that this rate of fluid loss would result in us arriving within operating limitations with an extra cushion of fluid that we both decided was comfortable. Around the mid flight we noticed that the rate of fluid loss had increased and decided to call operations to come up with a plan of where to land. It was determined that a nearby airport would be the most suitable; and at this point; the a hydraulic system was still operating normally with a hydraulic fluid quantity 5-10% above the minimum amount required. We had planned for the possibility of a hydraulic a failure and reviewed the abnormal procedures for this type of malfunction. We notified ATC of our need to divert and that the reason was because of a slow hydraulic leak. We did not need or ask for assistance at this point. Everything was normal operations on the arrival until we extended the landing gear. We anticipated that a problem might occur with gear extension and therefore extended the gear much earlier than normal to give us time to troubleshoot if needed. At that point our hydraulic fluid level made a significant drop to a level below the minimum quantity. This resulted in the amber 'hydraulic lvl a low' cas message. We declared an emergency and completed the appropriate abnormal checklist. We completed an approach and landing in accordance with the abnormal checklist and used the back-up pneumatic systems for braking and steering. The aircraft came to a complete stop on the runway without incident. We were in contact with emergency personnel and they chocked the airplane. We determined that the aircraft was safe and remained onboard until a tug arrived to pull us to a center.

Google
 

Original NASA ASRS Text

Title: A C750 lost significant hydraulic quantity throughout the course of a flight. Upon diverting and lowering the landing gear; most of the A System fluid was lost. An emergency was declared.

Narrative: I accepted the aircraft for two flights. While at the first destination it was noticed that the hydraulic quantity on the A system was lower than normal; but well within operating limitations. We checked for possible fluid leaks and I noted this information and flew to the second destination. Upon arrival; there was a slight reduction in the quantity of hydraulic fluid in the A side which prompted us to call our Maintenance Department. We were advised to monitor the quantity and that the aircraft would be serviced upon completion of our next day of flying. We departed the next morning to position for the passenger leg. Before we departed we made sure to check hydraulic quantities of both systems and inspected for possible leaks. The quantity had not changed from the previous inspection. Upon arrival in at the first destination; we noticed that the quantity of hydraulic fluid had again decreased; but only slightly and still well within operating limitations. We departed for a long flight to our second destination and upon reaching the cruise phase we noticed that the quantity had now decreased by about 10-15%; but was still within operating limitations. At this point we decided to monitor any further fluid loss. The fluid remained at the same level for over an hour before decreasing by 1%. We determined that this rate of fluid loss would result in us arriving within operating limitations with an extra cushion of fluid that we both decided was comfortable. Around the mid flight we noticed that the rate of fluid loss had increased and decided to call Operations to come up with a plan of where to land. It was determined that a nearby airport would be the most suitable; and at this point; the A hydraulic system was still operating normally with a hydraulic fluid quantity 5-10% above the minimum amount required. We had planned for the possibility of a hydraulic A failure and reviewed the abnormal procedures for this type of malfunction. We notified ATC of our need to divert and that the reason was because of a slow hydraulic leak. We did not need or ask for assistance at this point. Everything was normal operations on the arrival until we extended the landing gear. We anticipated that a problem might occur with gear extension and therefore extended the gear much earlier than normal to give us time to troubleshoot if needed. At that point our hydraulic fluid level made a significant drop to a level below the minimum quantity. This resulted in the amber 'HYD LVL A LOW' CAS message. We declared an emergency and completed the appropriate abnormal checklist. We completed an approach and landing in accordance with the abnormal checklist and used the back-up pneumatic systems for braking and steering. The aircraft came to a complete stop on the runway without incident. We were in contact with emergency personnel and they chocked the airplane. We determined that the aircraft was safe and remained onboard until a tug arrived to pull us to a center.

Data retrieved from NASA's ASRS site as of April 2012 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.