EASA SIB 2009-07: Resetting Tripped Circuit Breakers.

What to do

Flight crews should only reset tripped circuit breakers in flight if absolutely necessary for safe flight and landing, and only attempt one reset per breaker. On the ground, resetting should be coordinated with maintenance after identifying the cause. Operators should ensure their manuals and training programs include clear policies and procedures consistent with manufacturer guidance regarding circuit breaker resetting. Thorough inspections should follow any circuit breaker trip during operation.

Summary

EASA Safety Information Bulletin No. 2009-07 titled "Resetting Tripped Circuit Breakers" addresses safety concerns related to resetting tripped circuit breakers in all aircraft types. It highlights incidents involving aircraft such as the Reims Cessna F172, Pioneer 300, and Cessna 310R where resetting circuit breakers led to fires, landing gear malfunctions, or crashes. The bulletin provides guidance on the risks of resetting circuit breakers in flight and emphasizes the importance of following manufacturer and operational procedures.

What changed

This new Safety Information Bulletin introduces guidance discouraging the routine resetting of tripped circuit breakers in flight except when essential for safe flight and landing, and only once per breaker. It clarifies that circuit breakers are designed to protect wiring and should not be used as switches, and it recommends coordination with maintenance before resetting breakers on the ground. The bulletin also notes the trend toward electronic circuit breakers and their operational considerations.

Why it matters

This bulletin is important for aviation professionals because improper resetting of circuit breakers can lead to electrical fires, system failures, and accidents, impacting flight safety. Operators, maintenance organizations, and flight crews must understand the risks and follow appropriate procedures to prevent hazardous situations. Compliance with these recommendations helps reduce the likelihood of in-flight emergencies related to electrical faults.