A BE76 DUCHESS LANDED WHEELS UP ON A TRAINING FLT.

Narrative

THIS INCIDENT OCCURRED DURING A PARTIAL PANEL (NAV #1 INOP AND DIRECTIONAL GYRO INOP); SINGLE ENG LOC ONLY APCH. MY STUDENT WAS THE PF. UPON REACHING FAF; THE LNDG GEAR WAS LOWERED BY THE STUDENT AND RPTED '3 GREEN; DOWN AND LOCKED' AND WAS VERBALLY VERIFIED BY MYSELF; AND A 700 FPM DSCNT RATE WAS ESTABLISHED TO MDA AT WHICH LEVELOFF WAS INITIATED. LCL ALTIMETER SETTING WAS OBTAINED THROUGH ARPT ADVISORY PRIOR TO DOING THE APCH. APPROX 10 SECONDS PRIOR TO THE PUBLISHED MISSED APCH; THE STUDENT WAS REQUESTED TO INITIATE A GAR. THIS WAS REQUESTED OF THE STUDENT TO DEMONSTRATE THE ACFT'S INABILITY TO CLB AS VXSE/VYSE (85 KTS). AT 85 KTS; ACFT DEMONSTRATED APPROX 100 FPM DSCNT RATE DUE TO HIGH AMBIENT AIR TEMP AND DECREASED ENG PERFORMANCE. THE STUDENT WAS SHOWN THE ACFT'S LACK OF CLB PERFORMANCE AND TOLD TO ABORT THE GAR AND LAND. THE GAR PROC IS FULL PWR ON OP ENG; GEAR UP; AND ESTABLISHED VX/VYSE. WHILE I WAS PERFORMING RADIO COMS ON ADVISORY FREQ; THE STUDENT WAS PREPARING THE ACFT TO LAND. THE ACFT WAS POSITIONED ON THE EXTENDED CTRLINE; AT THE MISSED APCH. THE STUDENT RETARDED PWR ON THE OP (L) ENG AND LOWERED FLAPS TO 35 DEGS; PROPS WERE ADVANCED FULL FORWARD; MIXTURE AND FUEL SELECTORS CHKED 'RICH' AND 'ON.' I WAS NOT AWARE THAT THE GEAR WAS STILL STOWED. NEITHER MYSELF NOR MY STUDENT; AT ANY POINT DURING THE FLT; RECALL HEARING A GEAR UNSAFE HORN. THE PROPS CAME IN CONTACT WITH THE GND AND I BEGAN SHUTTING THE ENGS DOWN. THE ACFT LANDED GEAR UP; CTRLINE WAS MAINTAINED WITH RUDDER; AND SHUT DOWN AND SECURED WHEN IT CAME TO REST. NO INJURIES HAD OCCURRED. FACTORS CONTRIBUTING TO THIS INCIDENT WERE: 1) INADEQUATE INSTRUCTOR SUPERVISION DURING A CRITICAL PHASE OF FLT. 2) THE STUDENT; RATED IN THE ACFT; FAILED TO PROPERLY PREPARE THE ACFT TO LAND. 3) INOP OR INAUDIBLE GEAR WARNING HORN; HEADSETS WERE USED. 4) THE AMBIENT AIR TEMP MAY HAVE CAUSED FATIGUE TO BOTH MYSELF AND MY STUDENT.