Incident Overview
A turbojet airplane was destroyed during a forced landing and subsequent fire after experiencing a loss of power in both engines during the initial climb after takeoff. The crew and passengers evacuated the burning airplane following the landing in a field.
Crew Reports
The pilot reported that both engines operated normally during taxi and pre-takeoff checks. He stated that after rotation, gear retraction, and flap retraction, "we struck birds taking No. 2 engine out." Upon losing the right engine, he advanced the thrust levers and observed that the left engine was producing only approximately 70% RPM with exhaust gas temperature (EGT) over the red line.
The copilot reported observing a large flock of birds straight ahead at approximately 500 to 1,000 feet above ground level, passing just off the nose to the left side. He immediately heard an engine flameout. Attempting to follow the single-engine checklist, he realized the airplane was losing airspeed and unable to maintain altitude. The pilot-in-command stated they were going down and heading for the best emergency landing spot.
Cockpit Voice Recorder Analysis
The Cockpit Voice Recorder (CVR) captured the pilot's statement "We hit a bird" and the copilot's response "Yep," immediately following a sound similar to a decrease in engine RPM. A sound spectrum plot and flight profile analysis revealed that one engine flamed out almost immediately after a "thump" sound on the CVR. The other engine's speed decreased and experienced stalls until the engine speed was reduced to flight idle.
Investigation Findings
Inspections of the airplane's fuel system, pneumatic system, engines, fuel controls, and fuel pumps revealed no pre-impact anomalies. No physical evidence of bird ingestion was found in either engine. Original engine certification tests indicated that compressor stalls occurred when a 2-4 ounce starling was ingested into the engine, but physical damage was very slight due to the all-steel construction and geometry. However, engine flameouts were not recorded during those certification tests.
A wildlife specialist conducted a bird count at the accident airport two days after the accident and reported a flock of approximately 800 European Starlings.
Probable Cause
The official finding stated that the accident was caused by the total loss of power to the right engine and the partial loss of power to the left engine after the airplane encountered a flock of birds during initial climb out, resulting in impeded ram induction airflow.