Narrative:

I was captain/PIC and the PF of flight apr/xa/00. Predep, departure, takeoff, climb, en route cruise were normal. On descent to jfk about 17000 ft, approach control requested that we increase our descent rate. As PF, I extended the speed brakes and shortly thereafter, we were alerted to an EICAS message: hydraulic pressure demand (4). I retracted the speed brakes and followed the appropriate irregular procedure. This resulted in the demand pump selector #4 being placed in the off position. ATIS information at jfk indicated runway 4R in use for landing. Approach was briefed, autobrakes 3 were selected and flaps 30 degree landing was planned. Jfk tower cleared us for the runway 4R approach and informed us that windshear was reported by a previous B747 with a +/-15 KTS within 300 ft of the ground. Our reference speed was 135 KTS for flaps 30 degrees. I added 15 KTS for reported wind conditions and made the target speed 150 KTS. Landing checklist was completed. We were in visual conditions below about 1400 ft AGL. I disconnected the autoplt and autothrottles and hand flew the aircraft. At 1000 ft AGL, I noticed the wind vector indicating 38 KTS from about 100 degrees. We were #2 to land about 3 1/2 mi behind another air carrier. At about 800 ft, the right seat first officer reported birds, which I observed to our front left and passing above our left wing. Tower cleared us to land when we were about 300 ft AGL and as I recollect, reported the wind 100 degrees at 17 KTS. Approaching 50 ft AGL, I removed the right crab with use of left rudder and slight right aileron down. I was looking down the end of the runway confirming our altitude and that the previous landed jet was clear of the runway. The initial landing was smooth with the upwind right wing lowered slightly. In that instant as the right gear touched down, the nose came up and the right wing also came up as if affected by a strong wind gust. I lowered the nose and right wing and controled the aircraft to track centerline. Rollout, parking, checklist and debriefing were normal. There was no mention or thought of anything unusual happening during the flight or landing. No one mentioned or had any possible thought that there might have been ground contact with an engine pod. On the following morning, I received a telephone call from our jfk chief pilot informing me that maintenance personnel reported finding a 2 inch by 8 inch scrape at the 6 O'clock position of the #4 engine pod during their overnight maintenance checks. I informed him that I was surprised and did not believe that the damage could have happened during our flight. I recounted our entire flight and landing sequence with him. I have since confirmed with the first officer who conducted the preflight before departure in narita that no damage was observed reference the #4 engine pod. I do not have any knowledge or idea as to what caused the 2 inch by 8 inch scrape in the #4 engine pod. In hindsight and relative to the aircraft reaction at touchdown, it is my opinion that it is possible that the aircraft acted different at touchdown than what my experience and training expected. My initial thought at the time was that we experienced a wind gust at the instant touchdown. Now I wonder if the inoperative #4 hydraulic demand pump may have played a part in the way the nose and right wing behaved at touchdown. The hydraulic system #4 provides pressure to the: 1) right outboard elevator, 2) right inboard elevator, 3) spoilers #5, #6, #7, #8, 4) right inboard aileron, 5) lower rudder, 6) right outboard aileron, 7) #4 thrust reverser, 8) normal brakes, 9) wing gear actuation, and 10) outboard trailing edge flaps. The #4 hydraulic demand pump is pwred by air pressure from the airplane pneumatic system and operates when in the automatic position when the respective engine driven output pressure is low. This landing did not have the use of the #4 hydraulic demand pump. At the instant of touchdown all of the above items #1 through #8 noted controls came into use simultaneously. Is it possible that the #4 hydraulic system became overloaded at that landing touchdown instant and adversely affected one or several of the above noted controls? I do not have the necessary engineering information available and have asked engineering to research this question further.

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Original NASA ASRS Text

Title: A LNDG B747-400 BALLOONS AFTER INITIAL TOUCHDOWN DURING A XWIND LNDG. POSTFLT INSPECTION REVEALS A SCRAPED #4 ENG POD AT JFK, NY.

Narrative: I WAS CAPT/PIC AND THE PF OF FLT APR/XA/00. PREDEP, DEP, TKOF, CLB, ENRTE CRUISE WERE NORMAL. ON DSCNT TO JFK ABOUT 17000 FT, APCH CTL REQUESTED THAT WE INCREASE OUR DSCNT RATE. AS PF, I EXTENDED THE SPD BRAKES AND SHORTLY THEREAFTER, WE WERE ALERTED TO AN EICAS MESSAGE: HYD PRESSURE DEMAND (4). I RETRACTED THE SPD BRAKES AND FOLLOWED THE APPROPRIATE IRREGULAR PROC. THIS RESULTED IN THE DEMAND PUMP SELECTOR #4 BEING PLACED IN THE OFF POS. ATIS INFO AT JFK INDICATED RWY 4R IN USE FOR LNDG. APCH WAS BRIEFED, AUTOBRAKES 3 WERE SELECTED AND FLAPS 30 DEG LNDG WAS PLANNED. JFK TWR CLRED US FOR THE RWY 4R APCH AND INFORMED US THAT WINDSHEAR WAS RPTED BY A PREVIOUS B747 WITH A +/-15 KTS WITHIN 300 FT OF THE GND. OUR REF SPD WAS 135 KTS FOR FLAPS 30 DEGS. I ADDED 15 KTS FOR RPTED WIND CONDITIONS AND MADE THE TARGET SPD 150 KTS. LNDG CHKLIST WAS COMPLETED. WE WERE IN VISUAL CONDITIONS BELOW ABOUT 1400 FT AGL. I DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES AND HAND FLEW THE ACFT. AT 1000 FT AGL, I NOTICED THE WIND VECTOR INDICATING 38 KTS FROM ABOUT 100 DEGS. WE WERE #2 TO LAND ABOUT 3 1/2 MI BEHIND ANOTHER ACR. AT ABOUT 800 FT, THE R SEAT FO RPTED BIRDS, WHICH I OBSERVED TO OUR FRONT L AND PASSING ABOVE OUR L WING. TWR CLRED US TO LAND WHEN WE WERE ABOUT 300 FT AGL AND AS I RECOLLECT, RPTED THE WIND 100 DEGS AT 17 KTS. APCHING 50 FT AGL, I REMOVED THE R CRAB WITH USE OF L RUDDER AND SLIGHT R AILERON DOWN. I WAS LOOKING DOWN THE END OF THE RWY CONFIRMING OUR ALT AND THAT THE PREVIOUS LANDED JET WAS CLR OF THE RWY. THE INITIAL LNDG WAS SMOOTH WITH THE UPWIND R WING LOWERED SLIGHTLY. IN THAT INSTANT AS THE R GEAR TOUCHED DOWN, THE NOSE CAME UP AND THE R WING ALSO CAME UP AS IF AFFECTED BY A STRONG WIND GUST. I LOWERED THE NOSE AND R WING AND CTLED THE ACFT TO TRACK CTRLINE. ROLLOUT, PARKING, CHKLIST AND DEBRIEFING WERE NORMAL. THERE WAS NO MENTION OR THOUGHT OF ANYTHING UNUSUAL HAPPENING DURING THE FLT OR LNDG. NO ONE MENTIONED OR HAD ANY POSSIBLE THOUGHT THAT THERE MIGHT HAVE BEEN GND CONTACT WITH AN ENG POD. ON THE FOLLOWING MORNING, I RECEIVED A TELEPHONE CALL FROM OUR JFK CHIEF PLT INFORMING ME THAT MAINT PERSONNEL RPTED FINDING A 2 INCH BY 8 INCH SCRAPE AT THE 6 O'CLOCK POS OF THE #4 ENG POD DURING THEIR OVERNIGHT MAINT CHKS. I INFORMED HIM THAT I WAS SURPRISED AND DID NOT BELIEVE THAT THE DAMAGE COULD HAVE HAPPENED DURING OUR FLT. I RECOUNTED OUR ENTIRE FLT AND LNDG SEQUENCE WITH HIM. I HAVE SINCE CONFIRMED WITH THE FO WHO CONDUCTED THE PREFLT BEFORE DEP IN NARITA THAT NO DAMAGE WAS OBSERVED REF THE #4 ENG POD. I DO NOT HAVE ANY KNOWLEDGE OR IDEA AS TO WHAT CAUSED THE 2 INCH BY 8 INCH SCRAPE IN THE #4 ENG POD. IN HINDSIGHT AND RELATIVE TO THE ACFT REACTION AT TOUCHDOWN, IT IS MY OPINION THAT IT IS POSSIBLE THAT THE ACFT ACTED DIFFERENT AT TOUCHDOWN THAN WHAT MY EXPERIENCE AND TRAINING EXPECTED. MY INITIAL THOUGHT AT THE TIME WAS THAT WE EXPERIENCED A WIND GUST AT THE INSTANT TOUCHDOWN. NOW I WONDER IF THE INOP #4 HYD DEMAND PUMP MAY HAVE PLAYED A PART IN THE WAY THE NOSE AND R WING BEHAVED AT TOUCHDOWN. THE HYD SYS #4 PROVIDES PRESSURE TO THE: 1) R OUTBOARD ELEVATOR, 2) R INBOARD ELEVATOR, 3) SPOILERS #5, #6, #7, #8, 4) R INBOARD AILERON, 5) LOWER RUDDER, 6) R OUTBOARD AILERON, 7) #4 THRUST REVERSER, 8) NORMAL BRAKES, 9) WING GEAR ACTUATION, AND 10) OUTBOARD TRAILING EDGE FLAPS. THE #4 HYD DEMAND PUMP IS PWRED BY AIR PRESSURE FROM THE AIRPLANE PNEUMATIC SYS AND OPERATES WHEN IN THE AUTO POS WHEN THE RESPECTIVE ENG DRIVEN OUTPUT PRESSURE IS LOW. THIS LNDG DID NOT HAVE THE USE OF THE #4 HYD DEMAND PUMP. AT THE INSTANT OF TOUCHDOWN ALL OF THE ABOVE ITEMS #1 THROUGH #8 NOTED CTLS CAME INTO USE SIMULTANEOUSLY. IS IT POSSIBLE THAT THE #4 HYD SYS BECAME OVERLOADED AT THAT LNDG TOUCHDOWN INSTANT AND ADVERSELY AFFECTED ONE OR SEVERAL OF THE ABOVE NOTED CTLS? I DO NOT HAVE THE NECESSARY ENGINEERING INFO AVAILABLE AND HAVE ASKED ENGINEERING TO RESEARCH THIS QUESTION FURTHER.

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.