FTW89DPJ07

The airspeed indcr was malfunctioning on a previous flt. Bfr taking off again, the plt was seen to disassemble the pitottube as if the remove foreign matter. On the next flt, he bgn a hi spd/low pass ovr rwy 35. At abt midfield, the acft entered a climb to aprx 800 to 1000 ft AGL. Nr the peak of the climb, there was a reduction of pwr & the acft mnvrd (turned left, then rgt, as if to enter a base turn for rwy 17). The lndg gear was extdd at abt 300 to 500 ft AGL, flwd by a turn (south) twd the rwy. After abt 45 deg of turn, the acft entered a steep dscnt & crashed. An exam revealed a rubber pitot line, pn 35-324323, was deteriorated & leaked. No otr preimpact part failure was fnd. Experimental categoryacft with svrl limitations: flts rstrd to TX; exhibition only; PIC was required to have an instructor's logbook endorse-ment or letter of authorization (loa) to oper the acft. Neither an endorsement nor loa was fnd. Plt had abt 1 hr in T-34ACFT; cannabinoids detected in plt's urine, but none fnd in his blood. Acft was not equipped with stall warning sys.