Investigation Summary
The sequence of failure began with an oil leak in the number four engine, which caused severe vibrations and prompted the crew to initiate a shutdown. However, the engine's starter-generator had already overheated significantly due to a lack of proper maintenance. This heat was intense enough to burn through the high-pressure oil tube used for the propeller feathering mechanism. When the crew attempted to feather the propeller to reduce drag, the pressurized oil escaped from the damaged tube and ignited upon contact with the hot engine components. The fire became uncontrollable, eventually burning through the engine's structural mounts. As the aircraft neared Chongqing, the entire engine assembly detached from the right wing. The sudden change in aerodynamics and structural integrity made the aircraft impossible to fly, leading to its impact with power lines and farmhouses.
Final Conclusions
The investigation concluded that the primary cause was poor maintenance. The overheating of the starter-generator and the subsequent failure of the oil lines were preventable through standard inspection and servicing protocols. The crash highlighted significant safety deficiencies in the Chinese civil aviation sector during its rapid expansion in the 1980s, leading to the immediate grounding of 17 other aircraft for safety inspections.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Starter-Generator
The component that overheated due to poor maintenance, providing the ignition source and damaging nearby lines.
Propeller Feathering System
The system used to turn propeller blades parallel to the airflow; its high-pressure oil line was compromised by heat.
Engine Mounts
The structural assembly that failed due to fire damage, leading to the loss of the number four engine.
Interesting Facts
- 01The aircraft was an Ilyushin Il-18D, a Soviet-designed four-engine turboprop.
- 02All 108 people on board, including 98 passengers and 10 crew members, were killed.
- 03The passenger manifest included 94 Chinese citizens, three Japanese nationals, and one British national; all 10 crew members were Chinese.
- 04The crash site was located approximately 5 kilometers northwest of Chongqing Baishiyi Airport.
- 05The fire was so intense that it caused the engine to physically detach from the wing before the crash.
Safety Actions & Advisories
Fleet Grounding and Inspections
Following the accident, the Civil Aviation Administration of China (CAAC) ordered immediate safety checks, resulting in the grounding of at least 17 aircraft for mechanical issues.