AN MD88 ON APCH AT 7000 FT DECLARED AN EMER DUE TO LOSS OF L HYD PRESSURE; QUANTITY OK. FOUND EXCESSIVE AIR IN HYD SYS.

Narrative

WHEN WE SELECTED SLATS EXTEND FOR THE APCH; THE L HYD PRESSURE DROPPED TO ZERO AND THE L HYD PRESSURE LOW MESSAGE CAME ON IN THE ANNUNCIATOR PANEL. L HYD QUANTITY ALSO INCREASED SHARPLY FROM 9 QUARTS TO 18 QUARTS. WE ACCOMPLISHED THE ABNORMAL PROCS WIHTOUT RECOVERING THE SYS AND DECLARED AN EMER FOR LNDG DUE TO THE SYS BEING INOP. HOWEVER; DUE TO THE REMAINING QUANTITY OF FLUID; I CONTACTED OUR COMPANY MAINT AT THE SAME TIME WE RPTED OUR IMPENDING EMER LNDG STATUS. MAINT AGREED THAT THIS APPEARED TO BE A CAVITATED SYS; AND THEY SUGGESTED CYCLING THE HYD PUMPS ON AGAIN. AFTER A MIN; PRESSURE RECOVERED; AND THE SYS OPERATED NORMALLY FOR THE REST OF THE FLT. UPON REACHING THE CHOCKS; MAINT FOUND A SIGNIFICANT AMOUNT OF AIR IN THE SYS AND WENT THROUGH A BLEED PROC. FOLLOWING THAT A CHK OF HYD COMPONENT OP WAS COMPLETED BY MAINT; AND THE ACFT WAS RETURNED TO SVC. I HAVE SUGGESTED TO OUR COMPANY'S TECHNICAL STAFF THAT THE ABNORMAL PROCS MIGHT BENEFIT FROM ALTERATION TO PERMIT MULTIPLE CYCLING ATTEMPTS IF QUANTITY REMAINS IN THE SYS. IT APPEARS RECOVERY REQUIRED A PERIOD OF SEVERAL MINS WITH THE PUMPS OFF PRIOR TO REACTIVATION.