What happened
On May 26, 2005, a Dornier Do 27 Q-5 was conducting a sightseeing flight near Speyer, Germany, carrying the pilot and five passengers. During the base leg of the approach to runway 17, the pilot noticed that the engine was no longer producing power. Because the aircraft's altitude was insufficient to reach the airfield in a glide, the pilot was forced to perform an emergency landing. After notifying air traffic control, the pilot maneuvered the aircraft over a built-up area along a road to reach a parking lot adjacent to the roadway.
The aircraft struck a tree and subsequently collided with 17 parked cars. The impact caused the landing gear to collapse, and the aircraft came to rest on its belly. While the 6 occupants sustained only light injuries, the aircraft was destroyed, and 17 vehicles sustained damage.
The investigation
The BFU examined the engine, carburetor, and fuel systems. The engine's twelve spark plugs showed no signs of improper combustion, and the engine casing showed no external damage that would explain an in-flight failure. The dual magnetos were found to be functioning correctly. Fuel levels were sufficient, and both mechanical and electrical fuel pumps showed no abnormalities during testing.
Upon inspection of the carburetor, investigators found that fuel flow could not be established during initial test runs. Further troubleshooting revealed that the discharge valve was jammed in the shut-off position within its guide rail, with the preceding spring fully compressed. Once the valve was manually released, the carburetor functioned according to all specifications with no further issues.
Findings
- The primary cause of the engine power loss was a jammed discharge valve in the carburetor, which prevented fuel from entering the engine.
- The aircraft's altitude was too low to maintain a glide to the runway following the engine failure, necessitating the emergency landing in the parking lot.