What was found
HELICOPTER INBOUND FOR LANDING WHEN PILOT NOTICED VIBRATION, MADE NORMAL LANDING. MAINT EXAM OF ROTOR SYS FOUND YELLOW BLADE CRACKED FROM TRAILING EDGE OF BLADE, BOTH TOP AND BOTTOM TO MAIN SPAR. CRACK LOCATED AT BLADE STA 71 OR 19.3750 INCHES FROM END OF ADJUSTABLE TAB. CRACK BEGAN AT T/E WITH A NICK ABOUT .0312 INCH AND FOLLOWED CRACKS THROUGH BOTH SIDES. ALSO ALONG THE CRACKS WAS A DENT FROM UNKNOWN CAUSES. ACFT HAD GONE THROUGH 100-HOUR INSP LESS THAN 6 HRS BEFORE THIS MALFUNCTION AND NO DAMAGE OR CRACKING DETECTED. CAUSE OF CRACK UNKNOWN. ADVISE ATTEN TO ROTOR SYS ON PRE-FLIGHT AND POST-FLIGHT INSP. NEW BLADE INSTALLED, AND TRACKED PER CHAP 7 OF MDHC MM. INSPECTED OTHER BLADES, NO DAMAGE OR NIC