What happened
On September 14, 2008, an AB-180 aircraft, registration PP-GAM, operated by Aeroclube de Erechim, was performing its third glider towing mission of the day at the Erechim Aerodrome. Shortly after takeoff, at an altitude of approximately 40 meters and 300 meters from the runway threshold, the engine experienced a drop in RPM followed by a total loss of power.
The glider crew successfully disconnected the tow cable and returned to the runway. However, the crew of the towing aircraft attempted a left-hand turn to return to the runway but lost control of the aircraft. The aircraft struck trees before impacting the ground, causing serious injuries to both pilots and significant damage to the airframe, engine, and propeller.
The investigation
CENIPA investigators examined the engine and found that a nut on the connecting rod bolt of cylinder number two had loosened because it had not received the proper torque during a previous maintenance overhaul. This caused the bearing to rotate and block the oil outlet, leading to overheating, friction, and subsequent engine failure.
The investigation also revealed that the pilots were focused on selecting an emergency landing site rather than maintaining aircraft control. Furthermore, the crew failed to release the glider tow cable during the emergency. The investigation noted that the aeroclub's Operations Manual lacked standardized emergency procedures for towing failures, and there was a lack of joint briefing between the glider and tow plane crews.