At Duncan Aviation, we have recently come across a number of Temperature Control Valves or Low Limit Control Valves on Challenger aircraft with cracked housings. The cracks are found generally when performing the 600 hour or 180 month inspections. For the most part, the cracks are visible at the air inlet fitting and can be caused by excessive torque being applied to the fitting or the age of the unit.
With P/N 979558-8 Temp Control Valve, the cracked inlet causes loss of servo pressure, preventing proper temperature modulation. The cracked inlet on the 979580-4 Low Limit Control Valve causes loss of servo pressure from the electromagnetic control valve, which could lead to ice build-up in the water separator.
The Duncan Aviation Accessory Shop can function test, repair or overhaul both of the valves for a fraction of the cost of the OEM.
For questions about this or other Challenger accessory technical issues, contact your Duncan Aviation Accessory Tech Rep.
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