What happened
On the night of March 21, 2023, at approximately 00:45 local time, a Cessna 337H was performing a scheduled local night flight at Carriel Sur Aerodrome (SCIE) in Talcahuano, Chile. The crew, consisting of a pilot, a co-pilot, and a systems operator, was conducting aerial work when the aircraft attempted to land on runway 20. During the landing sequence, the pilot lost directional control, causing the aircraft to veer left of the runway centerline. The aircraft traveled approximately 35 meters across the terrain before coming to a complete stop.
All three occupants of the aircraft escaped without injury. However, the aircraft sustained significant structural damage, including a deformed fuselage, a fractured vertical stabilizer fairing, and damage to the external camera sensor. The landing gear also sustained heavy impact, with the left main gear assembly being particularly affected.
The investigation
DGAC Chile investigators examined the aircraft and its systems to determine why the pilot lost control. A primary focus of the technical inspection was the landing gear indication system, as the green light signaling that the gear was down and locked failed to illuminate when the pilot moved the selector to the down position.
Maintenance personnel and investigators conducted functional tests on the hydraulic and electrical systems. While the hydraulic lines showed no leaks and the emergency extension pump was fully operational, the electrical inspection revealed that the green indicator bulb was functional and the circuit breakers were intact. The investigation shifted focus to the mechanical components of the landing gear itself.
Findings
- The investigation established that the left main landing gear failed to lock into the down position during the landing.
- A mechanical failure was identified in the stop assembly of the left main gear, which prevented the gear from properly engaging the downlock mechanism.
- This mechanical malfunction caused the landing gear to collapse upon touchdown, leading to the loss of directional control and the subsequent runway excursion.
- The aircraft's external Trakka TC-300 sensor and various fuselage components sustained damage due to the impact with the ground.