What happened
On February 8, 1979, at approximately 20:14 local time, an EMB 110C, registration PP-SBB, operated by TAM Transportes Aéreos Regionais, crashed near Fazenda Monte Alegre in Agudos, São Paulo. The aircraft had departed from Bauru for São Paulo with an approved flight plan to level 070. Witnesses near the impact site observed the aircraft flying at an altitude of approximately 1,800 feet with engines functioning normally, landing gear retracted, and navigation lights active. However, shortly after being seen, the aircraft underwent a sudden and drastic change in attitude, impacting the ground with a steep dive and a significant right-wing low angle.
The investigation
CENIPA investigators examined the wreckage and found that both engines were still producing a minimum of 65% Ng at the moment of impact. A critical finding during the debris analysis was the absence of the bolt (PN 464 P3 A8) used to secure the control rod to the TAB-FLAP automatic trim linkage, along with its associated nut, washer, and rod fragment. Examination of the mounting holes showed no signs of the bolt being forcibly sheared off, leading investigators to conclude that the bolt was not installed in the aircraft at the time of the accident.
Investigators theorized that the missing bolt allowed the control rod to move freely, inducing vibrations. These vibrations, combined with elevator movements, could have caused the rod to shift backward, potentially causing the automatic trim to lock in an upward position. This would have created a nose-up pitch moment too powerful for the pilots to counteract using manual trim.
Findings
- The investigation could not definitively determine if the material or operational factors contributed to the crash, though the missing trim linkage bolt was identified as a primary mechanical concern.
- The aircraft's takeoff weight exceeded the maximum allowable limit by 125 kg due to an error in calculating the basic empty weight.
- Previous flight reports from late 1978 had noted vibrations in the rudder and elevator control systems.
- There was evidence of potential design interference where the trim tab tip could strike the fiberglass tail cone if excessive deflection occurred.
- All occupants perished in the accident.