Narrative:

This ASRS concerns a situation that involved an ill-defined, ambiguous equipment malfunction that the flight crew gradually perceived over a series of flts. Specifically, I raise the dilemma of what is the pilot's responsibility in relaying to the maintenance department a cogent write-up of a near- intangible malfunction that may well have existed, but was not recognized, for several legs, especially when the pilot's perception of prior legs may have a direct bearing on the maintenance department's ability to troubleshoot. I experienced the situation where an event suddenly crystallized my perception, and I could say 'we have felt this before,' but did not recognize it at the time. I recently flew a B757-400 on a series of 3 flts: anchorage-kodiak- anchorage-seattle. I flew the first leg into kodiak. The approach was made in VMC with strong, gusting xwinds and continuous light, and occasionally, moderate turbulence. I flew the plane to a firm xctled touchdown. During rollout the copilot asked if it had felt as though the plane had squatted to the right just as it touched down. I had not perceived that, but I had been fighting to keep the right wing down during the touchdown. We decided to carefully inspect the gear, struts, etc, but no abnormality was found during the walkaround. The copilot flew the 2ND leg back to anchorage. After an uneventful flight and a visual approach a smooth touchdown was made. Winds were near calm. We both commented on what a smooth landing it was, especially considering the previous landing at kodiak. I flew the 3RD leg to seattle. I shot an ILS and landed at night, in rain, with another right hand crosswind. The smooth touchdown was immediately followed by a pronounced and abrupt lurch or squat to the right. The event was over in less than a second. It became instantly clear to both of us that we had indeed felt something similar in kodiak, but that it had been masked by the turbulence and gusts. In retrospect, we may have experienced a very subtle version of it in anchorage, but it was so smooth that it did not arouse our suspicions. I wrote a detailed description of the seattle landing in the maintenance logbook and questioned whether or not there was an asymmetric ground spoiler deployment, or a squat switch problem. I specifically mentioned that we had made 3 lndgs with the aircraft and had felt this phenomenon. I did not elaborate, but I wanted maintenance to know that this was not a random fluke attributable to pilot technique on a rainy, windy, night landing. There was definitely something wrong with the aircraft, and it had taken 3 lndgs for us to even realize it. After our startling experience in seattle, I was very much concerned about a 'cannot duplicate, operations check normal' maintenance sign-off, which would put the aircraft in another crew's unsuspecting hands.

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Original NASA ASRS Text

Title: B737-400 ACFT. RPTR CAPT PERCEIVES A PROB WHEN LNDG IN XWIND. JUST AFTER TOUCHDOWN WITH WING DOWN XWIND, RPTR BELIEVES THAT THE ACFT LURCHES AND SQUATS IN THE DIRECTION OF THE XWIND. THE AIRLINE MAINT WAS UNABLE TO FIND A PROB.

Narrative: THIS ASRS CONCERNS A SIT THAT INVOLVED AN ILL-DEFINED, AMBIGUOUS EQUIP MALFUNCTION THAT THE FLC GRADUALLY PERCEIVED OVER A SERIES OF FLTS. SPECIFICALLY, I RAISE THE DILEMMA OF WHAT IS THE PLT'S RESPONSIBILITY IN RELAYING TO THE MAINT DEPT A COGENT WRITE-UP OF A NEAR- INTANGIBLE MALFUNCTION THAT MAY WELL HAVE EXISTED, BUT WAS NOT RECOGNIZED, FOR SEVERAL LEGS, ESPECIALLY WHEN THE PLT'S PERCEPTION OF PRIOR LEGS MAY HAVE A DIRECT BEARING ON THE MAINT DEPT'S ABILITY TO TROUBLESHOOT. I EXPERIENCED THE SIT WHERE AN EVENT SUDDENLY CRYSTALLIZED MY PERCEPTION, AND I COULD SAY 'WE HAVE FELT THIS BEFORE,' BUT DID NOT RECOGNIZE IT AT THE TIME. I RECENTLY FLEW A B757-400 ON A SERIES OF 3 FLTS: ANCHORAGE-KODIAK- ANCHORAGE-SEATTLE. I FLEW THE FIRST LEG INTO KODIAK. THE APCH WAS MADE IN VMC WITH STRONG, GUSTING XWINDS AND CONTINUOUS LIGHT, AND OCCASIONALLY, MODERATE TURB. I FLEW THE PLANE TO A FIRM XCTLED TOUCHDOWN. DURING ROLLOUT THE COPLT ASKED IF IT HAD FELT AS THOUGH THE PLANE HAD SQUATTED TO THE R JUST AS IT TOUCHED DOWN. I HAD NOT PERCEIVED THAT, BUT I HAD BEEN FIGHTING TO KEEP THE R WING DOWN DURING THE TOUCHDOWN. WE DECIDED TO CAREFULLY INSPECT THE GEAR, STRUTS, ETC, BUT NO ABNORMALITY WAS FOUND DURING THE WALKAROUND. THE COPLT FLEW THE 2ND LEG BACK TO ANCHORAGE. AFTER AN UNEVENTFUL FLT AND A VISUAL APCH A SMOOTH TOUCHDOWN WAS MADE. WINDS WERE NEAR CALM. WE BOTH COMMENTED ON WHAT A SMOOTH LNDG IT WAS, ESPECIALLY CONSIDERING THE PREVIOUS LNDG AT KODIAK. I FLEW THE 3RD LEG TO SEATTLE. I SHOT AN ILS AND LANDED AT NIGHT, IN RAIN, WITH ANOTHER R HAND XWIND. THE SMOOTH TOUCHDOWN WAS IMMEDIATELY FOLLOWED BY A PRONOUNCED AND ABRUPT LURCH OR SQUAT TO THE R. THE EVENT WAS OVER IN LESS THAN A SECOND. IT BECAME INSTANTLY CLR TO BOTH OF US THAT WE HAD INDEED FELT SOMETHING SIMILAR IN KODIAK, BUT THAT IT HAD BEEN MASKED BY THE TURB AND GUSTS. IN RETROSPECT, WE MAY HAVE EXPERIENCED A VERY SUBTLE VERSION OF IT IN ANCHORAGE, BUT IT WAS SO SMOOTH THAT IT DID NOT AROUSE OUR SUSPICIONS. I WROTE A DETAILED DESCRIPTION OF THE SEATTLE LNDG IN THE MAINT LOGBOOK AND QUESTIONED WHETHER OR NOT THERE WAS AN ASYMMETRIC GND SPOILER DEPLOYMENT, OR A SQUAT SWITCH PROB. I SPECIFICALLY MENTIONED THAT WE HAD MADE 3 LNDGS WITH THE ACFT AND HAD FELT THIS PHENOMENON. I DID NOT ELABORATE, BUT I WANTED MAINT TO KNOW THAT THIS WAS NOT A RANDOM FLUKE ATTRIBUTABLE TO PLT TECHNIQUE ON A RAINY, WINDY, NIGHT LNDG. THERE WAS DEFINITELY SOMETHING WRONG WITH THE ACFT, AND IT HAD TAKEN 3 LNDGS FOR US TO EVEN REALIZE IT. AFTER OUR STARTLING EXPERIENCE IN SEATTLE, I WAS VERY MUCH CONCERNED ABOUT A 'CANNOT DUPLICATE, OPS CHK NORMAL' MAINT SIGN-OFF, WHICH WOULD PUT THE ACFT IN ANOTHER CREW'S UNSUSPECTING HANDS.

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.