Case Study: HONEYWELL for the Recommissioned B-52H’s

An Innovative Approach to Cooling Jet Engine Lubricants.

Re-Manufacturered for Better Performance, Higher Resistance to Extremes & Vibration.


  • Originally Designed in the 50’s, Updated to 2016 Standards
  • Unique Design Features Make Oil Coolers Manufacturable
  • Innovative Production Techniques Improve Final Product
  • Heavy-duty Construction Insures Length of Service

The original design for the B-52 Bomber Oil Cooling system was invented more than 60 years ago. Now that the aircraft are being re-commissioned, replacements had to be created. ACE was chosen because of our reputation for excelling with difficult metal milling, forming and assembly.

Production began with the CNC, milling the fine grooves on the face on a ¾” block of pure aluminum, to shave weight. These “fins” maximize the cooling effect of air passing over the surface. This technique required some practice rounds to get to a thickness where the metal fins wouldn’t tear or crumple.

Once the panels were completed, a hard wax was used to fill-in the grooves. This prevented crushing the fins during forming the flat panel into a curved section. A back panel was attached over cells in-back through which oil flows. This panel held cells in place during the forming process.

A custom stand, or fixture, was designed and built for the curved units for final assembly work, welding, and finishing.

The B-52H Oil Coolers are curved to an exact arc, and when joined end-to-end, they wrap completely around the inside perimeter of the engine nacelle, where airflow is at its peak – cooling the oil travelling through the cells, inside.


  • A 3D print of the sophisticated shape was key in the production. We used the model for production analysis and determined that to make this part, the curved form had to start as a flat shape for CNC milling. Our 3D-modeling software enabled our manufacturing engineers to flatten the form and precisely plot the outer edges for trimming.

    Once the panel was milled, and the outer edge was trimmed, the flat 1″-thick aluminum panel was locked-down to the bed of our large CNC mill, and thin fins were created by carving grooves.