What happened
On July 2, 2010, a PIPER PA-28-235, registration EC-LDP, was conducting a local flight pattern at Sabadell Airport (LELL) to renew its airworthiness certificate. The flight was operated by Aircambrils and carried a pilot and an inspector from the State Agency for Aviation Safety (AESA).
During the flight, the pilot performed an engine-out stall approach maneuver at the request of the inspector to test the stall warning system. As part of the maneuver, the pilot applied carburetor heat. Upon attempting to accelerate to recover the aircraft, the engine failed to respond and subsequently stopped. Due to the low altitude at the time of the failure, the pilot was unable to attempt an engine restart or reach the runway. The aircraft performed an emergency descent and landed in a field east of runway 31. The impact caused significant damage to the airframe, including the fuselage, wings, and landing gear, and caused the engine components, such as the carburetor, to detach.
The investigation
The investigation examined the aircraft's maintenance history, the execution of the flight maneuver, and the operational procedures used by the flight inspection office. Investigators found that the aircraft's maintenance had been performed according to manufacturer instructions. However, the inspection of the engine revealed that the spark plugs were worn beyond recommended limits and were excessively dirty, and the magneto points were set below the recommended gap specifications.
Regarding the maneuver, the investigation noted that the flight was conducted at an altitude of approximately 2,000 ft, which was significantly below the 3,500 ft safety altitude recommended in the aircraft's flight manual. Furthermore, the use of carburetor heat during the maneuver did not align with the manufacturer's recommended procedures for the prevailing atmospheric conditions.
Findings
- The crew performed an engine-out stall approach maneuver without maintaining the required safety altitude specified in the flight manual.
- The engine failure occurred during the maneuver and could not be recovered due to the insufficient altitude.
- The use of carburetor heat was not in accordance with the established flight manual procedures.
- The low altitude prevented the pilot from attempting an engine restart or successfully returning to the aerodrome.
Safety action
- It is recommended that AESA develop written protocols for flight inspections to standardize procedures across all Flight Safety Offices.
- It is recommended that AESA define specific zones for conducting flight tests to ensure that safety altitudes are respected during maneuvers.