Introduction
On 6 January 2022, at 11:59 local time, a Piper PA-34-200T Seneca, registration HK5078, operating as an air ambulance, was involved in a serious incident during landing at Aeropuerto Enrique Olaya Herrera in Medellín, Colombia. The flight originated from Aeropuerto El Caraño in Quibdó, Chocó. The aircraft was on a special air work flight with six occupants: pilot, copilot, doctor, paramedic, patient, and companion.
Flight History
The flight proceeded normally. Upon arrival in the Medellín control area at 11:50 local time, the aircraft was cleared to land on runway 02. The pilot executed a normal landing. During the deceleration roll, the nose landing gear retracted, causing the nose of the aircraft to drop onto the runway. The aircraft slid approximately 20 meters (the summary states 80 meters) before coming to a stop. The pilot notified air traffic control and requested airport rescue and firefighting services, which responded immediately.
Occupants evacuated the aircraft unassisted and without injury. The incident occurred in daylight under visual meteorological conditions. No fire occurred.
Injuries and Damage
All six occupants were uninjured. The aircraft sustained substantial damage: inspection revealed damage to propeller blades, sudden stoppage of both engines, structural damage, and damage to the forward cargo compartment due to the nose gear retraction.
Investigation
The Colombian Accident Investigation Directorate (DIACC) was notified by the control tower and the operator. One investigator was dispatched to Medellín. DIACC notified the NTSB as the state of design and manufacture, which assigned an accredited representative.
The investigation found that the firewall had ruptured at the brace reinforcement. The rupture was caused by cracks that developed from the installation of rivets that did not meet manufacturer specifications. This allowed the reinforcement sheet to move rearward, which in turn allowed the nose landing gear to retract during deceleration.
Probable Cause and Contributing Factors
The probable cause was determined as: rupture of the firewall at the brace reinforcement, which cracked due to the installation of rivets that did not meet the manufacturer's specifications, causing a rearward movement of the sheet that produced the retraction of the landing gear during the deceleration of the aircraft after landing.
Contributing factors included: lack of effective maintenance processes to anticipate, prevent, or detect failures in nose landing gear mechanisms, such as the reinforcement sheet, considering Service Bulletin No. 1123D and the operational usage and stresses; and deficient maintenance practices where the reinforcement sheet was repaired without respecting manufacturer specifications and using non-specific or incorrectly placed aviation rivets.
Safety Recommendations
The investigation issued three safety recommendations to address the identified issues, but their content is not specified in the source.