Narrative:

A lear 60 was returned to service with all proper documents from quality control. At this time, company Y PF mr X (assistant chief pilot/maintenance officer) and PNF mr Y (chief pilot) performed a standard exterior and interior preflight per afm with no defects noted. After further normal preflight duties, fueling, WX briefing, filing an IFR flight plan, the crew departed fll with 2 crew members, and 2 passenger en route to home base of ZZZ. Takeoff, climb and cruise flight were perfectly normal with no anomalies. At approximately 90 NM from the destination of ZZZ, the crew asked for and received a clearance to start the en route descent. Shortly thereafter, the PF reported a master caution light with 2 amber hydraulic lights oscillating on and off very fast. Immediately, the crew checked the hydraulic pressure, per the abnormal hydraulic pressure light(south) checklist, and found the hydraulic pressure normal. A decision was made at this time to divert to an airport with a longer runway, the crew not knowing if this was an indicator problem or a real hydraulic problem. At this time the crew decided to run the hydraulic system failure/alternate gear extension checklist. While moving the flap selector to 8 degrees, the crew noted a decrease in the hydraulic pressure. It was at this point the crew knew this was not an indicator problem, but a real indication of a hydraulic malfunction or leak. Continuing with the checklist, the crew was able to extend the main landing gear normally, but hydraulic pressure was erratic. The crew knew this was a condition of urgency and elected to declare an emergency and clearance to YYY because per the checklist, normal landing distances should be increased by a factor of 3. While en route to YYY, the crew followed the 'hydraulic system failure landing' checklist and was able to extend flaps to about 30 degrees or 80% of normal landing flaps. Noted by the crew during extension of the main landing gear and flaps, that the hydraulic pressure would fall well below the normal operating range, and return to approximately 1/2 normal after actuation had been completed. While in the radar pattern for an ILS to runway 13L at YYY, the abnormal hydraulic system failure landing checklist was completed. The aircraft broke out of IMC at approximately 700 ft AGL. Touchdown was normal and pneumatic braking was applied, stopping the aircraft in approximately 5800 ft of the 10000 ft available. It was noticed at this time by the PNF (after rollout and the aircraft was stopped), the red fire annunciator on the APU illuminated briefly 2 times, and then remained on. The PNF activated the APU halon fire bottle, and started an evacuate/evacuation of the 2 passenger. The first officer secured the aircraft in place and exited the aircraft but noted no secondary indications of an APU fire such as bleed air lights on the annunciator panel or a call from the tower or fire boss on frequency. The fire boss inspected the aircraft and declared the aircraft as fire safe. With the passenger safe, the crew inspected the aircraft and noted the #1 main landing gear tire flat spotted, and a large amount of hydraulic fluid on the right side of the fuselage emanating from the right wheel well area. At this point, the aircraft was towed clear of the runway and stored for the night.

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Original NASA ASRS Text

Title: LEAR 60 FLT CREW HAS HYD SYS MALFUNCTION AND DIVERTS TO YYY.

Narrative: A LEAR 60 WAS RETURNED TO SVC WITH ALL PROPER DOCUMENTS FROM QUALITY CTL. AT THIS TIME, COMPANY Y PF MR X (ASSISTANT CHIEF PLT/MAINT OFFICER) AND PNF MR Y (CHIEF PLT) PERFORMED A STANDARD EXTERIOR AND INTERIOR PREFLT PER AFM WITH NO DEFECTS NOTED. AFTER FURTHER NORMAL PREFLT DUTIES, FUELING, WX BRIEFING, FILING AN IFR FLT PLAN, THE CREW DEPARTED FLL WITH 2 CREW MEMBERS, AND 2 PAX ENRTE TO HOME BASE OF ZZZ. TKOF, CLB AND CRUISE FLT WERE PERFECTLY NORMAL WITH NO ANOMALIES. AT APPROX 90 NM FROM THE DEST OF ZZZ, THE CREW ASKED FOR AND RECEIVED A CLRNC TO START THE ENRTE DSCNT. SHORTLY THEREAFTER, THE PF RPTED A MASTER CAUTION LIGHT WITH 2 AMBER HYD LIGHTS OSCILLATING ON AND OFF VERY FAST. IMMEDIATELY, THE CREW CHKED THE HYD PRESSURE, PER THE ABNORMAL HYD PRESSURE LIGHT(S) CHKLIST, AND FOUND THE HYD PRESSURE NORMAL. A DECISION WAS MADE AT THIS TIME TO DIVERT TO AN ARPT WITH A LONGER RWY, THE CREW NOT KNOWING IF THIS WAS AN INDICATOR PROB OR A REAL HYD PROB. AT THIS TIME THE CREW DECIDED TO RUN THE HYD SYS FAILURE/ALTERNATE GEAR EXTENSION CHKLIST. WHILE MOVING THE FLAP SELECTOR TO 8 DEGS, THE CREW NOTED A DECREASE IN THE HYD PRESSURE. IT WAS AT THIS POINT THE CREW KNEW THIS WAS NOT AN INDICATOR PROB, BUT A REAL INDICATION OF A HYD MALFUNCTION OR LEAK. CONTINUING WITH THE CHKLIST, THE CREW WAS ABLE TO EXTEND THE MAIN LNDG GEAR NORMALLY, BUT HYD PRESSURE WAS ERRATIC. THE CREW KNEW THIS WAS A CONDITION OF URGENCY AND ELECTED TO DECLARE AN EMER AND CLRNC TO YYY BECAUSE PER THE CHKLIST, NORMAL LNDG DISTANCES SHOULD BE INCREASED BY A FACTOR OF 3. WHILE ENRTE TO YYY, THE CREW FOLLOWED THE 'HYD SYS FAILURE LNDG' CHKLIST AND WAS ABLE TO EXTEND FLAPS TO ABOUT 30 DEGS OR 80% OF NORMAL LNDG FLAPS. NOTED BY THE CREW DURING EXTENSION OF THE MAIN LNDG GEAR AND FLAPS, THAT THE HYD PRESSURE WOULD FALL WELL BELOW THE NORMAL OPERATING RANGE, AND RETURN TO APPROX 1/2 NORMAL AFTER ACTUATION HAD BEEN COMPLETED. WHILE IN THE RADAR PATTERN FOR AN ILS TO RWY 13L AT YYY, THE ABNORMAL HYD SYS FAILURE LNDG CHKLIST WAS COMPLETED. THE ACFT BROKE OUT OF IMC AT APPROX 700 FT AGL. TOUCHDOWN WAS NORMAL AND PNEUMATIC BRAKING WAS APPLIED, STOPPING THE ACFT IN APPROX 5800 FT OF THE 10000 FT AVAILABLE. IT WAS NOTICED AT THIS TIME BY THE PNF (AFTER ROLLOUT AND THE ACFT WAS STOPPED), THE RED FIRE ANNUNCIATOR ON THE APU ILLUMINATED BRIEFLY 2 TIMES, AND THEN REMAINED ON. THE PNF ACTIVATED THE APU HALON FIRE BOTTLE, AND STARTED AN EVAC OF THE 2 PAX. THE FO SECURED THE ACFT IN PLACE AND EXITED THE ACFT BUT NOTED NO SECONDARY INDICATIONS OF AN APU FIRE SUCH AS BLEED AIR LIGHTS ON THE ANNUNCIATOR PANEL OR A CALL FROM THE TWR OR FIRE BOSS ON FREQ. THE FIRE BOSS INSPECTED THE ACFT AND DECLARED THE ACFT AS FIRE SAFE. WITH THE PAX SAFE, THE CREW INSPECTED THE ACFT AND NOTED THE #1 MAIN LNDG GEAR TIRE FLAT SPOTTED, AND A LARGE AMOUNT OF HYD FLUID ON THE R SIDE OF THE FUSELAGE EMANATING FROM THE R WHEEL WELL AREA. AT THIS POINT, THE ACFT WAS TOWED CLR OF THE RWY AND STORED FOR THE NIGHT.

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.