What happened
On November 5, 1999, a Cessna C-210 L, registered as PT-JZL, departed from Oriximiná, Pará, bound for Óbidos, Pará. The aircraft was operated by Táxi Aéreo Itaituba Ltda and was carrying one pilot and one passenger. Approximately five minutes after takeoff, while cruising at 1,500 feet, the pilot noticed an abnormality in the engine, which quickly progressed into a total engine seizure. To avoid the dense surrounding forest, the pilot performed an emergency landing in a cleared, deforested area near the community of Ananizal. While the aircraft sustained severe damage to the engine, horizontal stabilizer, and elevator, both occupants emerged uninjured.
The investigation
CENIPA investigators examined the Continental IO-520-L engine and found significant internal damage. Upon opening the engine, inspectors discovered a large amount of metal debris (swarf) within the oil reservoir. The investigation revealed that the crankshaft had broken at the third main bearing, with the fracture surfaces showing clear evidence of fatigue and torsional stress.
Further analysis determined that the crankshaft had been forged using the AIRMELT process rather than the more modern and secure VAR (Vacuum Arc Remelt) process. The investigation established that Airworthiness Directive (AD) 97-26-17 required the replacement of all AIRMELT-forged crankshafts with VAR-forged components. Although the engine had undergone a major overhaul only 173 hours prior to the accident, the owner had specifically opted not to replace the crankshaft to avoid the associated costs, despite being aware of the directive.