What happened
On 13 September 2010, an Agusta A-109E, registration PP-MPE, was taxiing at Congonhas Airport (SBSP) for a planned ferry flight to the Metropolitan Office helipad. The aircraft was operating at its maximum takeoff weight with two crew members on board.
As the aircraft progressed approximately 25 meters along the taxiway, it abruptly leaned to the left. Recognizing the danger of the rotor blades being positioned too close to the ground, the pilot immediately shut down the engines and applied the rotor brake. Upon exiting the aircraft, the crew discovered that the left main landing gear strut had sustained significant damage, including a deformed cylinder rod and a severed threaded rod end.
The investigation
CENIPA investigators examined the damaged components, specifically the actuating cylinder and the strut, which were analyzed by the Aerospace Technology and Science Department (DCTA). The metallurgical analysis focused on the thinnest point of the threaded rod end where the fracture occurred.
The investigation evaluated two primary hypotheses: a manufacturing defect or a structural failure caused by an external load. Investigators ruled out a manufacturing defect due to the lack of similar reported incidents for this aircraft type and the fact that the component had been in service for 850 flight hours and 2,830 landings.
Findings
- The primary cause of the failure was an overload of the landing gear component, which exceeded the material's resistance limits.
- The investigation concluded that an unreported, prior event—such as a hard landing, a collision with a pothole or obstacle, or excessive lateral force—had likely applied enough stress to weaken the part, leading to the eventual breakage during taxi.
- The aircraft was operating at its maximum allowable takeoff weight at the time of the incident.
- There were no injuries to the crew members.