Flap System Reliability: Cessna 441
Efficiently modeling the complete dynamics of large systems requires hierarchies. Here the hierarchies of the hydraulic system are reused to describe the reliability of a Cessna 441 flap system.
Cessna 441 Conquest II flap system.
Hydraulic Power & Flap Subsystem
The hydraulic power system provides pressurized fluid to the flaps and landing gear subsystems. The pumps, valves, cylinders, and filters are all assigned lifetime distributions.
Hydraulic power plant of the aircraft. The power plant pumps fluid with the right pressure to the flap system.
The hydraulic actuated flap system. The flap system enables the plane to fly at a lower speed while maintaining its lift, or allows it to land at a steeper angle of descent without any increase in speed.
The reliability for the subsytems can be computed after the parameters for the components are added to the model.
With the lifetime distributions for both the hydraulic power subsystem and the flap subsystem, a combined lifetime distribution for the full system can be created. The full system will work if both the hydraulic power and the flaps work.
Hierarchical model containing two ReliabilityDistributions combined to show the lifetime of the full system.
Creating random variates from the reliability distribution
of the combined system leads to an efficient way to simulate many runs of the system.
100 simulated runs of the full system until the first failure. The mean time to failure (MTTF) is displayed in red.
The survival function and the MTTF for the combined system. The MTTF is 40,000 flights, assuming that the flaps are active for 8 minutes per flight.