What happened
On December 6, 2008, a Pipistrel Taurus 503, registration EI-ECS, was conducting a check flight at Birr Airfield, Co. Offaly, to prepare for its Permit to Fly. The flight was manned by a check pilot and the aircraft owner. During the initial climb, the Rotax 503 UL engine abruptly ceased operation.
Following the stoppage, the crew attempted several restarts. During this process, the aircraft's descent rate increased significantly because the engine and propeller remained in the extended position, creating high drag. While attempting to return to the runway, the aircraft lost sufficient altitude and the pilot attempted a forced landing in a nearby field. During the approach, the aircraft struck the upper branches of an ash tree and subsequently impacted a garden. While the occupants sustained only minor cuts, the aircraft was damaged beyond economical repair.
The investigation
The AAIU investigation focused on the sequence of events leading to the loss of altitude and the mechanical state of the aircraft. Investigators found that the engine's sudden failure may have been caused by carburetor icing, as weather conditions were conducive to such an occurrence.
Crucially, the investigation established that the crew's attention was diverted by the engine failure and the subsequent attempts to restart the powerplant. This distraction led to a failure to monitor the flight path and the aircraft's height. Furthermore, the investigation noted that the aircraft's drag profile changed drastically with the engine extended, a factor that was not adequately accounted for during the emergency maneuvering. The investigators also identified that the aircraft lacked external markings to indicate the presence of an installed ballistic parachute system, which presented a potential hazard to first responders.
Findings
- The engine stopped unexpectedly during the climb, possibly due to carburetor icing.
- The crew was distracted by repeated attempts to restart the engine, leading to inadequate monitoring of the aircraft's altitude and glide path.
- The rate of descent was effectively doubled because the engine and propeller remained extended, increasing aerodynamic drag.
- The pilot lacked specific experience with this particular high-performance motor glider type, which hindered the emergency response.
- There were no external warning placards on the aircraft regarding the ballistic parachute system.
Safety action
As a result of the investigation, several safety recommendations were issued:
- The Irish Aviation Authority, EASA, and the State of Slovenia are advised to require clear external warning placards on aircraft equipped with ballistic parachute systems to protect emergency responders.
- Pipistrel is recommended to update its Flight and Maintenance manuals to include specific warnings regarding the potential for sudden engine stoppage in the Rotax 503 UL engine.