Investigation Summary
The flight was a scheduled service from Salzburg to Brussels with a stopover in Frankfurt. After departing Frankfurt at 15:20 local time, the aircraft reached the initial climb phase when the crew experienced a simultaneous power loss in both Pratt & Whitney R-2800 engines. Following standard emergency procedures, the crew retracted the flaps to reduce drag, but the aircraft was at an insufficient speed and altitude to maintain flight. The investigation revealed that lead deposits had been continuously building up on the spark plugs. As the engines reached high operating temperatures during the takeoff roll and climb, these deposits became conductive, creating a circuit that shorted the plugs and caused the engines to fail. The investigation also considered whether the pilot's decision to continue the takeoff or the timing of flap retraction contributed to the stall, but ultimately noted that the power loss might have been so severe that the crash was unavoidable.
Final Conclusions
The primary cause was the short-circuiting of the engine spark plugs caused by heavy lead deposits that formed a conductive path when heated during takeoff. A possible contributory factor was the pilot's decision to continue the takeoff and the retraction of landing flaps at a dangerously low speed and altitude, though the severity of the power loss may have made the disaster inevitable regardless of crew action. The investigation found no evidence that the lead coating occurred suddenly, suggesting a continuous process of accumulation.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Spark Plugs
Heavy lead deposits on the plugs became conductive at high temperatures, causing a short circuit and engine power loss.
Landing Flaps
Retracted by the crew during the emergency; the investigation noted this may have occurred at too low a speed for the remaining engine power.
Pratt & Whitney R-2800 Engines
Both engines failed to produce sufficient thrust during the critical climb phase.
Interesting Facts
- 01All 44 occupants, including 40 passengers and 4 crew members, perished in the crash.
- 02The aircraft was a Convair CV-240-12 built in 1949 with serial number 154.
- 03The crash occurred approximately two miles (three kilometers) north of Frankfurt Airport.
- 04The investigation found that lead deposits on the spark plugs had been building up continuously over time.
- 05The aircraft was completely destroyed by impact forces and a post-crash fire.
Safety Actions & Advisories
Spark Plug Overhaul Review
The investigation questioned whether the overhaul periods for spark plugs specified by the engine manufacturers were adequate in all operating conditions.