Narrative:

While flying at FL400 en route to ZZZ1; the left and right hydraulic low annunciators illuminated; as well as all 3 spoiler system fail annunciators. Hydraulic pressure decreased to 500-1000 psi for about 10 mins; then went to zero. During this time; my fellow co-captain and I started to look at suitable landing sites. We were east of ZZZ approximately 50 NM when the event occurred -- so we looked at the WX in the ZZZ area. ZZZ showed overcast skies approximately 1700 ft with good visibility. I called the tower on #2 radio and they confirmed runway was in good condition -- no precipitation. After calculating the landing distance needed with emergency brakes only -- we declared an emergency with center. We were radar vectored for the ILS runway 35R. The manual gear extension took awhile; so we requested a go around for more time. After extending the landing gear a landing was made successfully -- however; without anti-skid the emergency brakes 'blew' the main tires. The aircraft and crew were fine -- no damage. We arranged for the aircraft to be jacked and put on 'dollies.' it was towed to a hangar and fixed. The culprit was a broken 'O-ring' on a hydraulic filter bulb -- which allowed fluid to leak out during the course of flight.

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Original NASA ASRS Text

Title: A RA390 LOST ALL HYDRAULIC PRESSURE. THE CREW DECLARED AN EMERGENCY AND DIVERTED. A HYDRAULIC SYSTEM FILTER 'O' RING FAILED.

Narrative: WHILE FLYING AT FL400 ENRTE TO ZZZ1; THE L AND R HYD LOW ANNUNCIATORS ILLUMINATED; AS WELL AS ALL 3 SPOILER SYS FAIL ANNUNCIATORS. HYD PRESSURE DECREASED TO 500-1000 PSI FOR ABOUT 10 MINS; THEN WENT TO ZERO. DURING THIS TIME; MY FELLOW CO-CAPT AND I STARTED TO LOOK AT SUITABLE LNDG SITES. WE WERE E OF ZZZ APPROX 50 NM WHEN THE EVENT OCCURRED -- SO WE LOOKED AT THE WX IN THE ZZZ AREA. ZZZ SHOWED OVCST SKIES APPROX 1700 FT WITH GOOD VISIBILITY. I CALLED THE TWR ON #2 RADIO AND THEY CONFIRMED RWY WAS IN GOOD CONDITION -- NO PRECIP. AFTER CALCULATING THE LNDG DISTANCE NEEDED WITH EMER BRAKES ONLY -- WE DECLARED AN EMER WITH CTR. WE WERE RADAR VECTORED FOR THE ILS RWY 35R. THE MANUAL GEAR EXTENSION TOOK AWHILE; SO WE REQUESTED A GAR FOR MORE TIME. AFTER EXTENDING THE LNDG GEAR A LNDG WAS MADE SUCCESSFULLY -- HOWEVER; WITHOUT ANTI-SKID THE EMER BRAKES 'BLEW' THE MAIN TIRES. THE ACFT AND CREW WERE FINE -- NO DAMAGE. WE ARRANGED FOR THE ACFT TO BE JACKED AND PUT ON 'DOLLIES.' IT WAS TOWED TO A HANGAR AND FIXED. THE CULPRIT WAS A BROKEN 'O-RING' ON A HYD FILTER BULB -- WHICH ALLOWED FLUID TO LEAK OUT DURING THE COURSE OF FLT.

Data retrieved from NASA's ASRS site as of January 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.