RAT Deployment Incident
On October 4, 2025, Air India flight AI-117, a Boeing 787-8 aircraft (VT-ANO), experienced an unexpected Ram Air Turbine (RAT) deployment while approaching
Birmingham. The incident occurred at a low altitude, 400 feet, during landing. Despite the uncommanded deployment, the pilot reported no immediate issues, and the aircraft landed safely. This event, however, triggered a thorough investigation by the Directorate General of Civil Aviation (DGCA), the Indian aviation regulator, due to the critical function of the RAT as an emergency power source.
DGCA's Response Actions
Following the mid-flight RAT deployment, the DGCA took swift action. They ordered Air India to reinspect the RAT stowage on all potentially affected aircraft. Emphasis was placed on planes where the power conditioning modules (PCMs) had been recently replaced. Furthermore, the DGCA sought a comprehensive report from Boeing, the aircraft manufacturer. The report was to include preventative measures, global data of similar incidents in the Boeing 787 fleet, and details from any service difficulty reports related to PCM changes from operators worldwide. This directive reflects the aviation regulator’s commitment to maintaining stringent safety standards.
Boeing's Role and Report
The DGCA requested a detailed report from Boeing in response to the uncommanded RAT deployment incident. This report was expected to provide an in-depth analysis of the situation. It should detail the preventive steps Boeing would implement to avoid similar incidents. Alongside, the report was to present global data on related events involving the Boeing 787 fleet, as documented in the company's Fleet Team Digest. Additionally, it was crucial for Boeing to supply insights from any service difficulty reports (SDRs) submitted by operators worldwide that were linked to PCM replacements. This approach highlights the importance of manufacturer collaboration in aviation safety investigations.
PCM Replacement Impact
The DGCA's investigation gave specific attention to aircraft with recently replaced Power Conditioning Modules (PCMs). The regulator's concern stemmed from the potential link between these module replacements and the unexpected RAT deployment. Air India was specifically directed to review the 'D' Check work package, guaranteeing all necessary actions related to the PCM module replacement had been properly executed. This emphasis reveals the crucial role of maintenance procedures and their influence on flight safety. PCM, or Power Control Module, replacements are a regular maintenance task, making it essential to ensure all aspects are correctly performed.
The RAT's Critical Function
The Ram Air Turbine (RAT) is a critical safety feature in aircraft design. It is an emergency system that activates automatically when an aircraft experiences a loss of main power, typically due to engine, hydraulic, or electrical system failures. The RAT deploys into the airstream and uses the airflow to generate emergency backup power. This backup power is vital to ensure the aircraft retains essential functions, allowing pilots to maintain control and safely land the plane. The deployment of a RAT is thus a significant event, triggering thorough investigations and safety protocols.
Ongoing Investigation Details
The DGCA's investigation into the RAT deployment incident is still underway. The main focus is to understand the precise cause of the unexpected activation. Officials stated that they would re-inspect RAT stowage on all Boeing 787 aircraft where the PCM module was replaced recently. Boeing confirmed that post-incident maintenance checks had been performed, and the aircraft was deemed airworthy and returned to service on October 5, 2025. The investigation aims to implement proactive measures to prevent similar incidents in the future, protecting aviation safety and passenger well-being.
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