Investigation Summary
The accident occurred during a charter flight from Frankfurt to New York with scheduled intermediate stops at London Heathrow and Shannon. After arriving from London and refueling at Shannon, the aircraft was cleared for takeoff. During the application of takeoff power, a loud noise was heard, and the crew immediately initiated an abandoned takeoff. The number 4 engine (outer right) had separated from its mounts due to extreme unbalanced loads following a propeller blade failure. The resulting damage ignited a fire that quickly engulfed the right wing and fuselage. While all humans on board escaped without injury, six dogs in the cargo hold perished. The intensity of the fire was such that one of the responding airport fire engines was also caught in the flames and destroyed. Additionally, an unspecified amount of mail and cargo was lost in the blaze.
Final Conclusions
The investigation determined that the primary cause was the fatigue failure of the number 1 propeller blade on the number 4 engine. Laboratory analysis revealed that the blade had been previously bent. This prior damage disrupted the compressive stresses in the shot peened area of the propeller blade, creating a point of weakness. When the blade failed during the high-stress takeoff phase, the resulting vibration and unbalanced forces were sufficient to shear the engine from the wing structure.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Propeller Blades
The number 1 blade of the number 4 engine failed due to fatigue, leading to catastrophic unbalance.
Engine Mounts
The mounts failed under the extreme loads generated by the unbalanced propeller, allowing the entire engine assembly to separate from the wing.
Emergency Chute
The crew and passengers utilized the emergency slide/chute to exit the aircraft within 30 seconds of the fire starting.
Interesting Facts
- 01The aircraft was delivered to Pan Am on May 28, 1954.
- 02The aircraft's Manufacturer Serial Number (MSN) was 44426.
- 03The propeller blade failure was attributed to a previous bend that compromised the shot peening treatment.
- 04All passengers and crew escaped the burning aircraft in approximately 30 seconds.
- 05Six dogs in the cargo hold were killed in the fire.
- 06The aircraft was operating as a charter flight at the time of the accident.
Safety Actions & Advisories
Propeller Blade Inspection Standards
The investigation highlighted the critical importance of inspecting propeller blades for physical damage, such as bends, even if they appear minor. Such damage can disrupt the compressive stresses provided by shot peening, leading to fatigue failure under normal operating loads.