Incident Summary
An air ambulance flight was transporting a male infant in an incubator to Clovis, New Mexico. During the descent into Clovis, the control yoke moved to the full forward position. The pilot eased back on the yoke, causing the nose to pitch up. The pilot was able to maintain control by using power and elevator trim, and elected to return to Albuquerque, where an uneventful landing was made.
Examination Findings
Postincident examination disclosed a drooping wire bundle beneath the pilot's seat, at fuselage station (F.S.) 122. The insulation around an H16A10 wire, which supplies power to the copilot's windshield heat, had chafed against the elevator down cable (part number 50-524439-31). This chafing caused a short circuit. Although the pilot did not detect the odor of smoke, the elevator cable was burnt through and had separated. No circuit breakers were opened, nor were any fuses blown.