What happened
On November 1, 2012, at approximately 12:35 p.m., a Grumman AA5 (registration HI 389) was performing a private flight after departing from runway 19 at Dr. Joaquín Balaguer International Airport. Shortly after reaching an altitude of approximately 400 feet, the pilot experienced engine roughness and a progressive loss of power.
In response to the engine failure, the pilot executed an emergency landing in a pasture located in El Higüero, Santo Domingo Norte. During the descent, the aircraft struck an electrical cable, which was severed upon impact. The aircraft subsequently encountered a dip in the terrain, causing the nose gear to collapse, and continued sliding into a barbed-wire fence. The impact caused significant damage to the airframe, including damage to the wings, horizontal stabilizer, and propeller blades, as well as the detachment of the engine mount.
All three occupants (the pilot and two passengers) escaped the wreckage uninjured.
The investigation
The CIAA investigation examined the aircraft's maintenance records, engine components, and fuel samples. Investigators found that the engine had suffered a total shutdown due to fuel contamination. Analysis of fuel samples taken from the fuel filter, carburetor, and fuel lines revealed a high concentration of water and sediment.
Additionally, the investigation looked into the operational environment at the airport. It was noted that aircraft parked on the remote ramp often have modified fuel filler necks with locks to prevent fuel theft. The investigation also reviewed the pilot's pre-flight actions, noting that the tanks had been drained to a low level during the pre-flight inspection.
Findings
- The primary cause of the engine failure was heavy contamination of the fuel with water and sediment.
- A contributing factor was the practice of leaving fuel tanks nearly empty to prevent theft, which allowed for significant moisture condensation to occur within the tanks while the aircraft was parked outdoors.
- The aircraft's damage was exacerbated by the terrain, specifically the impact with an electrical cable and the collision with a fence and a dip in the ground.