Narrative:

The following was classified as an incident by the FAA FSDO person at yip. The incident involved loss of directional control in a twin aircraft during landing roll in a moderate crosswind condition. In a statement to the FAA, made less than 1 hour after the occurrence, I still had not fully realized what had happened. The aircraft had veered sharply to the left during an otherwise normal rollout. Application of right brake produced no effect and the left engine did not respond quickly enough to counter the progressing ground loop. Another factor I failed to mention in the FAA statement I now believe was: residual wake turbulence on the runway from an medium large transport that landed less than 2 mins prior to my arrival. The initial swerve was not consistent with the reported wind velocity or tail-high rollout position of the small transport. It was abrupt and of a large magnitude. I now believe that I discounted the possible wake turbulence factor presented by the previous aircraft and the crosswind, while blowing most of the threat from the runway as I thought it would, left some of the left wing vortice in the right side of the runway. I encountered this while rolling out with most of the weight of the aircraft on the left (upwind) landing gear. I believe the vortice contributed to the swerve and lifting, very slightly, the right wing and landing gear, which would account for the lack of braking action on the side when it was critically needed. I was advised of the crosswind and prepared for its effect. I was given the standard wake turbulence warning and acknowledged it. I weighed the effect of the crosswind and planned to land beyond the point at which the medium large transport lowered its nose, but I obviously must have misjudged the point.

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Original NASA ASRS Text

Title: SMT LOSS OF CONTROL ON LNDG ROLLOUT RESULTS IN GND LOOP.

Narrative: THE FOLLOWING WAS CLASSIFIED AS AN INCIDENT BY THE FAA FSDO PERSON AT YIP. THE INCIDENT INVOLVED LOSS OF DIRECTIONAL CONTROL IN A TWIN ACFT DURING LNDG ROLL IN A MODERATE XWIND CONDITION. IN A STATEMENT TO THE FAA, MADE LESS THAN 1 HR AFTER THE OCCURRENCE, I STILL HAD NOT FULLY REALIZED WHAT HAD HAPPENED. THE ACFT HAD VEERED SHARPLY TO THE LEFT DURING AN OTHERWISE NORMAL ROLLOUT. APPLICATION OF RIGHT BRAKE PRODUCED NO EFFECT AND THE LEFT ENG DID NOT RESPOND QUICKLY ENOUGH TO COUNTER THE PROGRESSING GND LOOP. ANOTHER FACTOR I FAILED TO MENTION IN THE FAA STATEMENT I NOW BELIEVE WAS: RESIDUAL WAKE TURB ON THE RWY FROM AN MLG THAT LANDED LESS THAN 2 MINS PRIOR TO MY ARR. THE INITIAL SWERVE WAS NOT CONSISTENT WITH THE RPTED WIND VELOCITY OR TAIL-HIGH ROLLOUT POS OF THE SMT. IT WAS ABRUPT AND OF A LARGE MAGNITUDE. I NOW BELIEVE THAT I DISCOUNTED THE POSSIBLE WAKE TURB FACTOR PRESENTED BY THE PREVIOUS ACFT AND THE XWIND, WHILE BLOWING MOST OF THE THREAT FROM THE RWY AS I THOUGHT IT WOULD, LEFT SOME OF THE LEFT WING VORTICE IN THE RIGHT SIDE OF THE RWY. I ENCOUNTERED THIS WHILE ROLLING OUT WITH MOST OF THE WT OF THE ACFT ON THE LEFT (UPWIND) LNDG GEAR. I BELIEVE THE VORTICE CONTRIBUTED TO THE SWERVE AND LIFTING, VERY SLIGHTLY, THE RIGHT WING AND LNDG GEAR, WHICH WOULD ACCOUNT FOR THE LACK OF BRAKING ACTION ON THE SIDE WHEN IT WAS CRITICALLY NEEDED. I WAS ADVISED OF THE XWIND AND PREPARED FOR ITS EFFECT. I WAS GIVEN THE STANDARD WAKE TURB WARNING AND ACKNOWLEDGED IT. I WEIGHED THE EFFECT OF THE XWIND AND PLANNED TO LAND BEYOND THE POINT AT WHICH THE MLG LOWERED ITS NOSE, BUT I OBVIOUSLY MUST HAVE MISJUDGED THE POINT.

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