EASA AD 26-017
Powerplant — Engine Firewalls — Modification
Summary
EASA Airworthiness Directive 26-017 is a proposed directive addressing engine firewall modifications for Airbus Helicopters SA 365, AS 365, and EC 155 models. It targets all serial numbers of SA 365 N, SA 365 N1, AS 365 N2, AS 365 N3, EC 155 B, and EC 155 B1 helicopters. The directive aims to improve engine compartment fire safety by enhancing firewall sealing.
What Changed
This new directive introduces a mandatory modification requiring the installation of angle-brackets along the engine compartment firewalls to close gaps found between seals and engine cowling. The modification is detailed in Airbus Helicopters Alert Service Bulletins AS365-71-33-0001 and EC155-71-33-0001, Revision 001 dated 01 October 2025. It is a new regulation and does not supersede any previous directives.
Why It Matters
This directive is critical for preventing fire propagation between engine compartments in the event of an engine fire, which could otherwise lead to loss of helicopter control. For operators and maintenance organizations, compliance ensures enhanced safety and effectiveness of fire extinguishing systems. It also helps maintain regulatory compliance and reduces risk of in-service incidents related to engine compartment fires.
What To Do
Operators of affected Airbus Helicopters models must modify the engine compartment firewalls by installing angle-brackets as per the specified Alert Service Bulletins. This modification must be completed within 7 months or 175 flight hours, whichever occurs first, after the directive's effective date. Stakeholders should review the ASBs and plan maintenance accordingly to meet the compliance deadline.
Your fleet's weekly compliance brief
AI-summarized regulatory changes, compliance deadlines, and action items — filtered to your aircraft, every Monday.
AI-generated summary from official EASA source document. Always verify against the original.