Fire prevention in the air


Extreme temperatures challenge commercial engine maker to find better solution to gearbox safety.

The Challenge

A large commercial aircraft engine manufacturer needed a fire safety relief valve to automatically drain hydraulic fluid from their gearbox should the temperature in the gearbox approach the flash point of the hydraulic fluid. Of course, the valve needs to remain leak-tight during normal use.

The biggest hurdle facing our customer was that there were no commercially available mechanical thermal valves able to operate in the extreme temperature range required by the engine back-up generator ( -65°F to 450°F.)

Despite multiple safety checks and sensors, there have historically been occurrences when oil-filled gearboxes have overheated and caused fires.

The Solution

Senior Metal Bellows developed a new thermal valve design using our bellows technology in conjunction with a reliable expansion media that provided the higher temperature actuation range required. An additional benefit to the all-mechanical design was fail-safe operation without the need for electronics or controls. As in all safety products, reliability was paramount in evaluating the success of the Senior Bellows solution.

The Results

Exceeded spec for temperature extremes (-65°F to +450°F), capable of low or high cycle life depending on application need, operates without the need for electronics/controls, designed to last the life of the aircraft.