EASA SIB 2012-16R1
Hydraulic Systems — Implementation of automatic Power Transfer Unit inhibition logic
Summary
EASA Safety Information Bulletin 2012-16R1 is an informational bulletin addressing hydraulic system improvements on Airbus A318, A319, A320, and A321 aircraft. It informs operators about the implementation of automatic Power Transfer Unit (PTU) inhibition logic designed to prevent overheating and failure of a second hydraulic system following a single hydraulic system failure with fluid loss. The bulletin references Airbus Service Bulletins that provide retrofit and activation instructions for this safety enhancement.
What Changed
This revision of EASA SIB 2012-16 includes reference to Airbus Service Bulletin A320-29-1156, which offers an optimized retrofit solution for automatic PTU inhibition. The bulletin updates previous guidance by incorporating this new service bulletin alongside earlier ones (A320-29-1115 and A320-29-1126) that introduced and activated the PTU inhibition logic. It highlights the availability of these design improvements and encourages their implementation.
Why It Matters
The automatic PTU inhibition logic reduces the risk of a secondary hydraulic system failure caused by PTU overheating after an initial hydraulic fluid loss. This enhancement improves hydraulic system reliability and safety, ensuring continuous availability of at least two hydraulic systems, which is critical for safe aircraft operation. Operators and maintenance organizations benefit from reduced risk of hydraulic system failures and associated operational disruptions.
What To Do
Operators should review their Airbus A318, A319, A320, and A321 fleets to determine if the PTU inhibition logic is installed and activated. For aircraft without the optional design, operators are recommended to either install and activate the logic using Airbus SB A320-29-1115 and SB A320-29-1126 or retrofit using SB A320-29-1156. For aircraft with the design installed but not activated, activation per SB A320-29-1126 is advised. No mandatory compliance deadline is specified.