FADEC Cooling Using High Temperature Loop Heat Pipes

The Full Authority Digital Engine Control (FADEC) controls engine operation.  It is historically mounted on the engine case to minimize the routing length of the sensor and actuator wiring.  The FADEC must be maintained below 70°C, while the environment can be as hot as 170°C.  The current design uses fuel to cool the FADEC, however, this often limits the allowable ground or flight idle time before the fuel is too hot to cool the FADEC.  The Phase I program demonstrated that a Loop Heat Pipe (LHP) and heat pipes can be combined into an adaptable thermal management system.  This system will use multiple heat sinks to remove the FADEC heat, passively selecting the best sink at different flight regimes.  Fuel cooling will not longer be required during ground idle.  The goal of the Phase II program will be to design, fabricate, and test a LHP thermal system for passively cooling the FADEC.  The LHP will operate at a higher temperature than conventional aluminum/ammonia LHPs.  The current design will use a titanium LHP, as well as heat pipes incorporated into the FADEC internals. BENEFITS: In addition to the FADEC, the thermal management system that will be developed under this program has the potential to benefit essentially all aircraft electronic systems (power electronics and controls) on both military and commercial platforms.  The first application for a FADEC with advanced thermal management capability is expected to be a future derivative of the F-35 which could realize significant benefit if an alternate heat sink could replace the current fuel heat sink.  The system can also be used for cooling electronic boxes in future military and commercial aircraft, as well as retrofitting current aircraft.  A second military application would be LHP cooling of electrical actuators.  Currently, these actuators require cooling air be ducted to them in the wing, which LHPs could eliminate. As electrical actuators replace hydraulic actuators on commercial aircraft, this concept could also provide cooling.