Outflow valve of civil aircraft controls the flow out of the cabin by adjusting the angle, and then achieves the purpose of controlling the pressure of aircraft cabin. In order to research the factors affecting the normal control of civil aircraft cabin pressure and provide reference for the design of cabin pressure control system (CPCS), a digital electric CPCS model was built by SIMULINK, in which the cabin pressure acquisition delay time, outflow valve movement delay time and outflow valve maximum move speed are changed respectively. The change trend of cabin pressure altitude, cabin pressure altitude change rate, outflow valve speed and angle are obtained. The results show the pressure acquisition delay time and outflow valve movement delay time have a great influence on the CPCS normal control. When the pressure acquisition delay time and outflow valve movement delay time are small, different outflow valve maximum movement speed have less impact on the CPCS normal control. When the pressure acquisition delay time or outflow valve movement delay time is large, the outflow valve maximum movement speed should also increase accordingly.
The model-based safety analysis(MBSA)has become increasingly mature since its inception and is more suitable for complex civil aircraft systems.On the basis of current research and ARP4761A draft,the MBSA method is used to study the failure assessment method of civil aircraft during the operation phase.Compared to tra-ditional methods,integrating operational data,functional failures,and equipment failures into the same model is more convenient for conducting operational failure assessment.Firstly,this paper defines the basic elements of the operational failure assessment model and sorts out the model construction process,and establishes equipment level,system level,and aircraft level models containing failure modules based on Simulink.The external lighting sub-sys-tem of a certain aircraft model was taken as an example to build the model,and a numerical analysis was conducted on the operational data of a certain fleet.The results show that the the error between MBSA and FTA results is with-in an acceptable range.At the same time,the FMEA analysis was performed,and the probability of loss of landing lighting function hazard was calculated and simulated using operational data.30 simulation results indicate that the probability of occurrence based on operational data fluctuates around the design value,slightly exceeding the overall design value,but still meeting the safety requirements.
Aiming at the traditional similarity analysis method, which is difficult to accurately and quantitatively assess the degree of difference in the reliability level between the target product and the similar product and the problem of low credibility, this paper establishes a similarity assessment table based on the level of the product parameters, which can intuitively determine the level of similarity between the products, as well as introduces a method of determining the similarity factor of the products with the help of the handbook or physics of failure (PoF) model of the failures in a quantitative way, and at the same time clarifies the correlation of the level of the equipment's importance and the level of confidence, so as to achieve the reliability prediction of the civilian electronic equipment in the graded classification, and to enhance the use of the value of the historical data and the credibility of the method of the similar products.
In order to study the friction characteristics of the spherical plain bearings of the civil aircraft high lift devices, a test equipment for friction performance of spherical plain bearings was proposed. The structural characteristics of the test equipment and the measuring principle of friction torque were introduced. A self-lubricating spherical plain bearing with a structure similar to that of the spherical plain bearing used in the high lift device was used in the test. The starting friction torques of self-lubricating spherical plain bearings were tested by this test equipment, and the friction torques of different types of self-lubricating spherical plain bearings under different rotational speeds, swing angles and radial loads were tested. The influence of these factors on the friction performance of the self-lubricating spherical plain bearings was analyzed. The results show that the speed in the low speed range has little effect on the friction performance of self-lubricating spherical plain bearing, and the equivalent friction coefficient decreases with the increase of load, and increases with the increase of swing angle and bearing size.
试飞相比一般航线飞行要面对更复杂的飞机构型状态、更加严苛的飞行环境、超常规的飞行包线和飞行动作等,同时也具有特定的资源条件,在试飞中应用机组资源管理方法,对保障试飞安全和提高试飞效率都有重要意义.通过对比航线飞行和试飞活动,从人的资源、机上资源、程序资源、监控资源和保障资源等五个方面分析试飞资源特点,从情景意识、沟通和决策等方面分析试飞中的机组资源管理要素,研究在试飞中应用机组资源管理方法.以颤振和发动机操纵特性试飞科目为例,说明如何在试飞实施中考虑人员配置、监控条件、机组分工、通信标准等CRM要素,实际试飞经验表明机组管理方法可有效促进机组沟通协作,有助于优化试飞资源配置,降低试飞成本和风险.
