What happened
On April 26, 2016, a Fairchild Swearingen SA-226T, registration N-125WG, was conducting a private VFR flight from Mutxamel, Alicante, to Andorra-La Seu d'Urgell. During the descent into the destination airport, the pilot observed flickering cockpit displays, signaling the onset of an electrical malfunction. Within two minutes, the aircraft suffered a total electrical failure.
As the aircraft approached the runway, the pilot attempted to extend the landing gear using the emergency procedure. During the landing on runway 21, the landing gear was not fully locked in the down position; it was still in the process of extending. Consequently, the propeller blades and the aircraft belly impacted the runway surface. The aircraft veered to the right, eventually coming to a stop on the runway shoulder. All 5 occupants (the pilot and four passengers) were uninjured and evacuated the aircraft on their own.
The investigation
The investigation focused on the sequence of the electrical failure and the execution of the emergency gear extension. Investigators examined the electrical system and found that while the right generator's current limiter was damaged, the left generator had likely failed approximately 30 minutes prior to the total battery depletion without triggering a cockpit warning light. This suggested a masked failure, possibly within the Generator Control Unit (GCU).
Regarding the landing gear, physical evidence and witness accounts confirmed that the gear doors were open and the gear was unlocked from the up position, but the mechanism was still in the early stages of extension upon impact. The investigation also reviewed maintenance records, noting discrepancies in the documentation and suggesting the aircraft's airworthiness certificate may not have been valid due to unconfirmed recent maintenance tasks.
Findings
- The primary cause of the accident was an error in applying the emergency landing gear extension procedure following the total electrical failure.
- A significant contributing factor was the decision to initiate a flight with a known deferred maintenance item regarding the right-side generator.
- The lack of recent training or simulation regarding emergency procedures contributed to the improper execution of the gear extension.
- The pilot's high level of versatility across many different aircraft types may have impacted the specific procedural execution required for this model.
- A failure in the left generator occurred without a visible cockpit warning, likely due to a malfunction in the GCU, which went undetected for roughly 30 minutes prior to the total loss of electrical power.