What happened
On April 7, 2016, at 11:25 UTC, a Douglas DC-3, registration HK2663, was performing a VFR cargo flight from Puerto Gaitán to Villavicencio. During the initial climb following takeoff from runway 04, the crew heard an explosion from the left engine. The failure was caused by the detachment of a cylinder head from the number one engine.
In an attempt to manage the emergency, the crew implemented engine failure procedures. However, the crew mistakenly applied the procedure to the functioning right engine instead of the failed left engine. By reducing the RPM on the number two engine while maintaining high power, the crew caused the engine to exceed its BMEP limits, leading to a loss of power in the remaining engine.
Unable to maintain altitude, the crew executed an emergency landing in an unprepared field approximately 1.37 NM from the airport. The aircraft struck a fence and impacted the terrain with its landing gear and flaps retracted. The impact caused the propellers to detach and triggered a post-crash fire that consumed approximately 80% of the forward fuselage. All 3 occupants evacuated the aircraft; the technician sustained minor injuries, while the pilots were uninjured.
The investigation
The GRIAA investigation focused on the sequence of engine power reductions and the mechanical failure of the number one engine. Investigators examined the cockpit controls and found that the RPM and power levers did not align with the required "ENGINE FAILURE – TAKE OFF" checklist. Specifically, the propeller control for the operational engine had been reduced, which prevented the aircraft from maintaining sufficient climb performance.
Physical evidence at the site showed fragments of a cylinder head near the runway, confirming the mechanical failure of the left engine. The investigation also noted that the operator did not provide recent flight hour data for the crew and failed to allow the inspection of the engines as required by Colombian regulations.
Findings
- The primary cause of the accident was the incorrect application of emergency procedures by the crew, specifically reducing the RPM of the operational engine.
- The engine failure was initiated by the detachment of a cylinder head on the number one engine.
- Deficient maintenance procedures failed to identify or prevent the component failure.
- The aircraft would have been capable of a safe single-engine climb if the second engine had not been compromised by the incorrect procedure.