C152 PLT MISCALCULATED XWIND COMPONENT; LANDED AND SKIDDED OFF THE RWY HITTING A TXWY MARKER SIGN.

Narrative

RETURNING TO HHR AFTER A XCOUNTRY TO SBA IN A C152. ATIS INFO WAS IN EFFECT INDICATING AN 8 KT WIND AT 310 DEGS WITH GUSTS TO 24 KTS. THE PLT INCORRECTLY CALCULATED THE RPTED WIND TO BE 40 DEGS OFF OF RWY 25 INSTEAD OF THE ACTUAL 60 DEGS. THE PLT APPROXIMATED THE XWIND COMPONENT AT BTWN 4-12 KTS WHICH WAS WITHIN THE DEMONSTRATED XWIND CAPABILITY OF THE ACFT. HAD THE PLT CORRECTLY CALCULATED THE ACTUAL DIRECTION OF THE RPTED WIND AND THE XWIND COMPONENT HE WOULD HAVE CHOSEN A MORE SUITABLE RWY FOR LNDG. EXAMINATION OF THE WINDSOCK ON SHORT FINAL SHOWED THE WIND TO BE 30 DEGS OFF THE RWY; SO THE PLT DID NOT RE-EXAMINE THE EARLIER MISCALCULATION. THE PLT HAD NO DIFFICULTY KEEPING THE ACFT ALIGNED WITH THE RWY ON APCH. JUST PRIOR TO TOUCHDOWN; THE WIND SHIFTED; THE AIRPLANE BEGAN SINKING RAPIDLY; LANDED HARD AND THE R WING LIFTED UP. FULL PWR AND INCREASED BACK ELEVATOR PRESSURE WERE APPLIED WHEN THE AIRPLANE BEGAN TO SINK; BUT THE PLANE LANDED HARD AND TURNED TOWARD THE L. THE RUDDER PRESSURE APPLIED WAS INSUFFICIENT TO KEEP THE PLANE ALIGNED WITH THE RWY. THE PLT BELIEVES ADDITIONAL R RUDDER PRESSURE WOULD HAVE CAUSED THE L WINGTIP TO HIT THE GND. THE AIRPLANE EXITED THE RWY TO THE L; THE PLT REMOVED PWR AND STOPPED ON THE ADJACENT PARALLEL TXWY. DURING THE EXCURSION FROM THE RWY; THE AIRPLANE HIT A TXWY MARKER SIGN. FACTORS: INCORRECT CALCULATION OF XWIND COMPONENT OF WIND; DECISION TO LAND WITH THE RPTED WINDS; THE WIND GUST AND THE LIGHTLY LOADED AIRPLANE. DAMAGE: MINOR. THE L TIRE WAS WORN BEYOND LIMITS DURING BRAKING AND WAS REPLACED. THE ADF ANTENNA ON THE AIRPLANE BELLY WAS LOOSENED AND REATTACHED. THE TXWY MARKER SIGN WAS KNOCKED DOWN AND DAMAGED BEYOND REPAIR.