Investigation Summary
Pan Am Flight 202 was on the third leg of a multi-stop journey from Buenos Aires to New York. After departing Rio de Janeiro, the aircraft proceeded on an off-airways route over the unexplored Amazon basin. The last radio contact occurred at 09:16 UTC, with the crew reporting they were abeam Barreiras at 14,500 feet. When the flight failed to make its next report at 10:45 UTC, a search was initiated. The wreckage was found scattered in three distinct sections, indicating a mid-air disintegration. The investigation focused on the Hamilton Standard Model 24260 propellers, which featured a hollow steel shell with a rubber core. This design was found to be susceptible to structural failure. In this instance, a propeller failure likely induced severe vibrations that tore the number 2 engine from its mountings, leading to a loss of control and the subsequent breakup of the airframe.
Final Conclusions
The Civil Aeronautics Board (CAB) determined the probable cause was the separation of the number 2 engine and propeller from the aircraft. This was caused by highly unbalanced forces, which led to the uncontrollability and disintegration of the aircraft. The specific reason for the initial propeller failure remained undetermined due to the inability to recover the number 2 engine and propeller from the dense jungle.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Hamilton Standard Model 24260 Propeller
Four-blade propellers with a rubber core filling a steel shell; the design was prone to structural failure and blade separation.
Pratt & Whitney R-4360 Wasp Major
28-cylinder radial piston engines; the number 2 engine separated from the wing due to unbalanced loads.
Interesting Facts
- 01The wreckage was scattered in three main sections: the main fuselage/starboard wing, the outer port wing (765 yards away), and the empennage/engine parts (1,100 yards away).
- 02The number 2 engine and its propeller were never recovered despite extensive search efforts in the dense jungle.
- 03The Boeing 377 Stratocruiser involved was christened 'Clipper Good Hope'.
- 04The crash site was located in extremely remote jungle, 281 nautical miles southwest of Carolina, Brazil.
- 05There had been two prior engine separation incidents involving the Boeing 377 in early 1950.
Safety Actions & Advisories
Propeller Design Review
The investigation highlighted the inherent risks in the hollow steel blade design of the Hamilton Standard propellers, leading to increased scrutiny and eventual phase-out of that specific blade construction in favor of safer alternatives.
Known Controversies & Unanswered Questions
Initial Rescue Abandonment
After the wreckage was first spotted on May 1, 1952, a rescue plane carrying a seven-person team circled the site for four hours but returned to base without dropping the team. Officials stated they did not jump because there were no signs of survivors, a decision that drew scrutiny given the remote location.
Missing Critical Evidence
The failure to locate the No. 2 engine and propeller assembly meant that the exact mechanism of the initial failure could not be definitively proven, leaving the investigation to rely on circumstantial evidence from the wing root and stabilizers.