A CFI ALONG WITH THE OWNER OF AN EXPERIMENTAL ACFT EXPERIENCED AN UNCONTROLLABLE OSCILLATING ROLL DURING TKOF. AN EMER LNDG WAS ATTEMPTED ON RWY REMAINING; RESULTING IN THE ACFT'S DEPARTURE TO THE LEFT SIDE OF THE RWY.

Narrative

RV-8A IS A TANDEM LOW WING ACFT; OWNER BUILDER WAS RECEIVING TRANSITION TRNG FROM RESPONDENT. PREVIOUSLY HAD RECEIVED TRNG ON GIVE FLTS IN SAME ACFT FROM SAME RESPONDENT. FIRST SUCH FLT HAD OWNER BUILDER IN REAR SET; SUBSEQUENT FOR FLT HAD OWNER BUILDER IN FRONT SEAT. DUAL FLTS NUMBERS THREE AND FOUR WERE TERMINATED EARLY DUE TO FUEL SYS ANOMALIES; SUBSEQUENTLY FIXED. DUE TO THESE EXPERIENCES WITH MECH ISSUES WITH THE ACFT; THE RESPONDENT WAS OF A MINDSET THAT WAS ALERT TO POSSIBLE SYS MALFUNCTIONS. THE FLT THAT IS BEING RPTED STARTED WITH FULL WX BRIEF FROM FSS; NO UNTOWARD WX INDICATIONS. START; TAXI; RUN-UP AND ALL PRETKOF CHECKS WERE CAREFUL; COMPLETE; AND SATISFACTORY. RWY 2 WAS INDICATED; ASOS RPTING WIND ABOUT 350 DEGS AT 5 KTS. TKOF ROLL WAS NORMAL: MANIFOLD PRESSURE; RPM; OIL PRESS AND TEMP; ROTATION SPD ALL NORMAL. PLT RECEIVING INSTRUCTION IN FRONT SEAT WAS FLYING. AFTER LIFT OFF AND AT ABOUT 20 FT AGL; ABOUT 1/3 WAY DOWN THE RWY; PLT FLYING BEGAN EXCLAIMING ('OH DEAR; OH DEAR')) AS IF SOMETHING WAS WRONG; AND ACFT BEGAN OSCILLATING IN ROLL. CFR; (RESPONDENT) IMMEDIATELY TOOK CTL OF ACFT; AND ASSUMING THE WORST; I.E.; POSSIBLE CTL SYS MALFUNCTION; DETERMINED TO LAND THE ACFT ON THE REMAINING RWY. TRANSFER OF CTL TOOK PLACE WITH THE ACFT WALLOWING/ROLLING LEFT AND RIGHT; OVER THE LEFT EDGE OF RWY; NO UNUSUAL PITCH DEVIATIONS WERE NOTICED; NOR AIRSPEED FLUCTUATIONS. (THE UNSTABILIZED APCH RESULTED IN A TOUCHDOWN AT ABOUT 1/2 -2/3 DOWN THE RWY; THREE BOUNCES; DAMAGING THE NOSE WHEEL STRUT. DISCUSSING THE EVOLUTION WITH LCL AVIATION SAFETY COUNSELOR; THE POSSIBILITY OF HORIZONTAL WIND SHEAR WAS RAISED. IN RETROSPECT; HAD WIND SHEAR BEEN RECOGNIZED; THE REMEDY (LOWER ANGLE OF ATTACK AD ACCELERATE; LEAVE PWR; FULL ON) WOULD HAVE BEEN IN CONFLICT WITH THE NEED TO AVOID OVER FLYING POPULATED AREA IN AN ACFT OF UNKNOWN MECH CTL SYS STATUS; I.E.; LNDG ON REMAINDER OF RWY MIGHT NO LONGER HAVE BEEN POSSIBLE; FORCING CONTINUATION OF FLT; AND NO ASSURANCE WAS AVAIL THAT OTHER FACTORS THAN WIND SHEAR WERE NOT INVOLVED. CONTRIBUTING FACTOR TO NOSE GEAR DAMAGE: ON FIRST FLT OF THIS ACFT BY ANOTHER PLT; NOSE WHEEL ASSEMBLY HAD BEEN DAMAGED AND SUBSEQUENTLY REPAIRED. LAST FLT BEFORE RPTED ONE INVOLVED A BOUNCED LNDG BY OWNER BUILDER RECEIVING INSTRUCTION. THE POSSIBILITY OF FATIGUE OR HIDDEN DAMAGE TO THE NOSE LNDG GEAR; NOT APPARENT TO VISUAL INSPECTION; CANNOT BE RULED OUT.