What happened
On February 21, 2017, an Embraer 190-200 LR, registration PR-AUO, was operating a flight from Confins (SBCF) to Vitória (SBVT) carrying 104 passengers and 5 crew members. During the descent phase at approximately 14,000 feet, a short circuit occurred within the passenger cabin on the left side, near seat 03A. The electrical failure caused overheating, sparks, and the production of smoke.
A flight attendant identified the issue and used a fire extinguisher to suppress the sparking. Due to the situation, the pilot declared an emergency and requested priority landing. The aircraft landed safely in Vitória without further incident, and all occupants remained unharmed. The aircraft sustained minor damage to the internal cabin lining.
The investigation
CENIPA investigators examined the area behind the passenger cabin sidewall, where the electrical wiring is located. The investigation focused on the wiring harness (PN 191-32836-401) and its interaction with the electromagnetic protection tray. Investigators found that the insulation on the conductors had been compromised, leading to exposed metal and evidence of melting consistent with a short circuit. Two circuit breakers related to the affected circuits had tripped during the event.
Additionally, the investigation looked into the crew's use of an axe to widen a gap in the cabin lining to access the source of the sparks. It was noted that existing regulations and training manuals did not provide specific guidance on using such tools without risking further damage to the aircraft structure.
Findings
- The short circuit was caused by the loss of wire insulation due to friction between the wiring harness and the electromagnetic protection tray.
- This friction occurred because the wiring was not properly secured, failing to meet the manufacturer's installation requirements.
- Evidence of similar wiring wear was found on other aircraft in the same production series, suggesting a potential manufacturing or assembly quality issue.
- The crew's use of an axe to access the fault area lacked specific procedural guidance in training manuals to prevent secondary damage to the aircraft.