What happened
On 5 November 2006, a Mainair Blade microlight, registration EI-DRH, was performing a private takeoff from the grass runway at Rathcoole Airfield in Co. Cork. During the takeoff roll, which was being conducted over rougher ground to maintain clearance from another taxiing aircraft, witnesses heard a loud bang followed by the immediate cessation of the engine. The pilot was able to abandon the takeoff and bring the aircraft to a halt, subsequently shutting down the engine. There were no injuries to the pilot, and no damage was caused to any third-party property.
The investigation
The investigation established that a spare pilot's helmet, which had been stored in a ballast bag in the unoccupied rear seat, escaped its container and was sucked into the engine's four-bladed carbon composite propeller. This impact caused one of the propeller blades to fracture and detach, and also resulted in damage to the radiator mounting.
The investigation examined the ballast bag used to carry the helmet. This bag featured a top compartment for personal items, secured by straps and a tie cord. It was noted that the tie cord had previously broken and, due to the manufacturing method, could not be replaced. The pilot indicated that he may have been distracted while securing the bag, potentially failing to ensure the top compartment was fully closed.
Findings
- The primary cause of the incident was the ingestion of a loose object into the propeller.
- The takeoff was performed over rough terrain, which likely contributed to the movement of the unsecured item.
- The pilot's attention may have been diverted while securing the ballast bag, leading to an improperly closed compartment.
- The design of the ballast bag's tie cord was a contributing factor, as the broken cord could not be easily repaired.
- The inherent design of a pusher-configuration microlight makes the propeller susceptible to foreign object damage (FOD) from items located in the open cockpit area.