DC8-61 FREIGHTER HAS TO RETURN TO DEP ARPT AFTER LOSING HYD PRESSURE TO THE MAIN SYS WITHOUT LOSS OF FLUID. DURING THE LAST 50 FT OF THE LNDG PROC THE PIC LOSES PARTIAL CTL OF ACFT DUE TO THE AILERONS BEING IN MANUAL REVERSION. ACFT #1'S ENG COWL STRIKE RWY; SUFFERING DAMAGE.

Narrative

LOST ALL HYD PRESSURE ON CLBOUT. NO LOSS OF QUANTITY. AILERON MANUAL REVERSION LIGHT ILLUMINATED. LNDG PHASE WITH ACFT ON STABILIZED APCH AT 50 FT; REDUCED PWR EXPERIENCED ADVERSE ROLL AND YAW TO L. ON LNDG ROLL #1 ENG FIRE WARNING LIGHT ILLUMINATED; NO BELL SOUNDED. COMPLETED ENG FIRE SEPARATION OR SEVERE DAMAGE CHKLIST. DISCHARGED FIRE AGENT. ON POSTFLT CHK DISCOVERED #1 ENG COWLING DAMAGE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT ON THE POSTFLT INSPECTION; THE GND CREW DID ADD ABOUT 6 QUARTS OF HYD FLUID. THE MAIN CAUSE OF THE PRESSURE LOST WAS CITED AS AIR IN THE LINES. THE ACFT; JUST THE DAY BEFORE; HAD LOST ALL OF ITS HYD FLUID AND THE LINES AROUND OR ASSOCIATED WITH #3 ENG HAD BEEN CHANGED; THE FLUID ADDED AND THE LINES BLED. PERHAPS THE BLEEDING WAS NOT DONE IN AN EFFECTIVE MANNER BY THE AIRLINE PERSONNEL AT GDL. THE DAMAGE TO THE #1 ENG COWLING IN THE SECOND EPISODE WAS COSMETIC WITH THE OIL COOLER DOOR BEING REPLACED. THE PIC SAID THAT IT IS TYPICAL OF THE DC8 TO PERFORM A BIT OF A DUTCH ROLL WHEN LOSS OF HYD PRESSURE IS EXPERIENCED. IT HAS TO DO WITH THE RUDDER/YAW DAMPER ACTUATOR. THERE WAS ALSO AN ASYMMETRICAL ENG PWR CONDITION; WITH #1 AND #2 ENGS NOT SPOOLING UP AS FAST AS #3 AND #4 ENGS.