EASA SIB SAIB-2025-05: Aircraft Fuel Indicating Systems

What to do

Operators of helicopters equipped for part 133 sideward-pulling Class C RLC operations should verify that their flight manual supplements specify the maximum bank angle, minimum useful fuel including a safety margin, and safe operating procedures for these conditions. If such information is missing, operators should contact the design approval holder to confirm whether these factors were considered and encourage amendments to the design approval if necessary. No compliance deadlines are specified.

Summary

The Special Airworthiness Information Bulletin SAIB: 2025-05 is an FAA informational bulletin addressing fuel starvation risks in helicopters, specifically MD Helicopters Model 369-series, during Title 14 CFR part 133 Class C Rotorcraft Load Combination (RLC) sideward-pulling operations. It highlights that fuel unporting at high bank angles can cause engine shutdown even when fuel quantity indicators show usable fuel levels. The bulletin provides guidance but does not mandate regulatory action.

What changed

SAIB: 2025-05 introduces awareness of fuel starvation hazards during extended high bank angle operations in sideward-pulling Class C RLC helicopter missions. It recommends updates to flight manual supplements to include maximum demonstrated bank angles, minimum useful fuel levels accounting for unporting, and safe operating procedures. The FAA plans to update advisory circulars 27-1B and 29-2C to reflect these concerns.

Why it matters

This bulletin is important for rotorcraft operators and maintenance teams because it identifies a previously unaddressed risk of fuel starvation during specific external load operations, which can lead to engine shutdown despite apparent sufficient fuel. Understanding these risks helps improve flight safety and operational planning, ensuring compliance with safe fuel management practices during Class C RLC operations.