Retrofitting control systems in aircraft manufacturing demands a careful approach, especially in environments like painting facilities, where reliability, safety, and maintainability are paramount. This manufacturer’s decision to modernize aging PLC-5 systems in two paint hangars led to enhanced operational stability, improved safety, and simplified maintenance, setting the stage for the future support of new aircraft models. Integrating Rockwell’s ControlLogix system and R. Stahl’s intrinsically safe (IS) components offered a sustainable solution aligned with the facility’s stringent standards.

Aircraft painting facilities rely on a series of interconnected systems—from paint application platforms and regulated air systems for temperature and airflow control to support systems for water, solvents, and waste management. For years, these facilities depended on Allen-Bradley’s PLC-5 platform, a technology from 1986 that was discontinued in 2017. Faced with potential issues due to age, limited parts availability, and reduced expertise, the manufacturer pursued a retrofit to modernize controls, replace outdated components, and enhance capabilities.

Key Reasons to Update the PLC-5 System

While the PLC-5 had a strong reliability record, aging systems posed unique challenges:

• Increased risk of component failures due to the age of the equipment
• Replacement parts no longer available, and limited availability of repair services
• Limited pool of support specialists for the product

To address these challenges, the manufacturer standardized on Rockwell Automation’s ControlLogix controllers, PowerFlex VFDs, and FactoryTalk View SE HMIs. By aligning with Rockwell’s Integrated Architecture, the company achieved benefits including:

• Simplified support through a familiar platform for both internal and external resources
• Reduced spare parts inventory requirements by using standardized components already utilized elsewhere in the facility
• Opportunities to reuse code modules across systems, providing a consistent look and feel for the onsite maintenance team

Safety and System Components in Hazardous Environments

The manufacturer faced a challenge: most systems in the paint facility included components that had to operate within a Class 1 Division 1 hazardous environment, requiring specific component selections and installation techniques to meet code requirements for this setting. A preference was given to intrinsically safe (I.S.) components and wiring practices, which ensure that energy levels within electronics and associated wiring do not spark or create sufficient energy to ignite. When appropriate I.S. devices were not available, explosion-proof devices and installation techniques were employed.

With I.S. systems, wiring circuits are conditioned before transitioning from “safe” areas to hazardous environments through energy-limiting devices known as intrinsic safety barriers (ISBs). This approach requires control enclosures that house the ISBs, running wiring from the safe area to devices within the hazardous zone. However, some I/O control equipment manufacturers offer products that can be installed directly in the hazardous zone, allowing I/O racks to be placed close to field devices and minimizing conduit and wiring needs. While many I.S. I/O solutions are limited to Class 1 Division 2 environments, the R. Stahl IS1+ product line, compatible with Class 1 Division 1 environments, was selected.

The IS1+ capabilities were reviewed for compatibility with Rockwell controllers and a broad range of field devices, and bench testing was performed before final product selection.

This updated configuration reduced complexity while enhancing safety, ultimately streamlining both initial installation and long-term maintenance.

Choosing a Future-Ready Control Platform

The selection of components during the retrofit was carefully considered to ensure not only reliable operation but also long-term supportability. Beyond the suitability of the components for effective system performance, important factors included the product lifecycle, the availability of skilled support resources, ensuring knowledgeable assistance for future maintenance; and spare parts compatibility, which helps reduce inventory needs by standardizing parts across the system.

Lasting Benefits of a Strategic Retrofit

The approach to modernizing the airline manufacturer’s painting facilities showcases how strategic system upgrades can extend the life of essential manufacturing assets. Through thoughtful component selection, hazard-conscious design, and alignment with Rockwell’s Integrated Architecture, the facility is now equipped to meet both current and future production demands. Retrofitting key systems in such complex environments not only enhances immediate operational capabilities but also safeguards the manufacturer’s investment well into the future.