Islom karimov nomidagi

Guidelines

This section is the fundamental discipline of "Safety" and more voluminous in the training material. The section studies the basic concepts and methodological foundations of ensuring flight safety, therefore, students are required to pay more attention to the study of topics heard at lectures, practical exercises, and especially self-study.

General concepts of safety and reliability.

Flight safety is a comprehensive characteristic of air transport and aviation operations, which determines the ability to perform flights without threatening human life and health. The probability of an accident occurring in flight (we call it the risk level and denote Q) is a complex function and depends on the properties of the aviation transport system (ATS), the parameters of the state and impact of the environment on the aircraft, operational factors and flight parameters. ATS properties can be represented by various parameters characterizing its individual elements (aircraft, crew, flight support services and ATM). We denote the vector of these parameters by X. The vector of state parameters and the impact on the aircraft of the external environment Y includes:

• barometric pressure, density, temperature and humidity, wind direction and speed, horizontal and vertical gusts of air and their gradients;

• electrical effects, icing, hail, etc.

Under operational factors are meant:

• composition of the crew;

• class and category of aerodromes, runway parameters and condition;

• flight duration;

• weight and alignment for all aircraft configurations provided;

• engine operating modes and duration of operation in certain modes;

• frequency and types of maintenance;

• assigned resource;

• features of the use of aircraft;

• characteristics of airways of ground-based flight support facilities;

• weather minimums;

• used fuel, oils, additives and other used special liquids and gases.

The vector of these flight parameters is denoted by Z.

The vector of flight parameters G includes:

• flight altitude;

• horizontal and vertical speeds;

• overloads, angles of attack, slip, roll and pitch.

One of the properties of the aviation transport system (ATS) is the possibility of generating in flight adverse factors that lead to airborne operations. These factors determine the functional state of the exchange from the point of view of flight safety at the moment. Denote the vector of these parameters by X (t).

Thus, the level of risk

                                   Q = F (X, Y, Z, G, X / t /). (3.1)

Reliability is understood as the property of an object to keep in time, within established limits, the values ​​of all parameters characterizing the ability to perform the required functions in the given modes and conditions of use, maintenance, repair, storage and transportation. Reliability is a complex property of an object, which, depending on its purpose and operating conditions, can include reliability, durability, maintainability, and storage for both the object and its parts. Moreover, an object can be a part, a unit, an aggregate, a system and an aircraft as a whole.

Reliability - the property of an object to continuously maintain a healthy state for some time or some operating time.

  Durability - the property of an object to maintain a healthy state until the limit state occurs with the installed system of maintenance and repair. Signs (criteria) of the limiting state are established by the normative and technical documentation for this object. Under the limit understand the state of the object in which its further operation should be stopped due to the fatal departure of the specified parameters beyond the set limits or fatal decrease in operating efficiency below the permissible.

Maintainability - the property of the object, which is adaptability to the prevention and detection of the causes of failures, damage and the elimination of their consequences through maintenance and repair. In relation to aviation technology, the term “operational manufacturability” has the most frequent use. The concept of operational manufacturability, being a broader one, also includes maintainability. The most important characteristic of an object is its operability. It is understood as the state of an object in which it is capable of performing specified functions, while maintaining the values ​​of specified parameters within the limits established by the normative and technical documentation.

Serviceability - the state of an object in which it meets all the requirements established by the regulatory and technical documentation. Depending on the type of production facility, one or more parameters (chassis release time, oil pressure in the oil system, gas temperature in the engine, etc.). Failure to comply with the relevant requirements set forth in the regulatory and technical documentation does not exclude the possibility of failures, malfunctions and damage during the operation of aircraft.

Special situations in flight and types of special situations

A special situation is any emergency situation in flight caused by exposure to a hazardous factor and requiring the crew (pilot) and flight control authorities to have unplanned, and most often immediate and extraordinary actions. In this case, any (real or potential) impact on any element of the aviation system that can lead to a special situation in flight and become the cause of an aviation (emergency) accident is considered a dangerous factor.

Special situations are classified according to the degree of danger of consequences for the crew (passengers) of the aircraft and aircraft as follows:

• complication of flight conditions;

• complex;

• emergency;

• catastrophic.

Failure is an event associated with the loss of operability of an object (system).

Dependent failure - failure of an object or element of an object due to damage or failure of other elements (objects).

Independent failure - failure of the object, not caused by damage or failure of other elements of the object.

By the nature of the manifestation, failures can be sudden or gradual (Fig. 5).

а б

Y Y




Y_доп Y_доп

0 t_отк *t=0 t 0 t₁ t₂ t

            

Fig. 5. Failures: a - sudden; b - gradual

Sudden failure is characterized by a sharp (spasmodic) decrease in performance below the permissible limit. A gradual failure is characterized by a gradual departure of the set parameters beyond the permissible limits. With a sudden failure, the time margin (* t) tends to zero, with a gradual failure - more than zero. In the "crew - aircraft" system, both sudden and gradual failures can occur. In the practice of flight operations, it is noted that sudden failures are more typical for the technical link, and gradual failures caused by personality factors are more typical for the human operator (crew members). By the nature of the causes of occurrence, all types of failures can be divided into deterministic (regular) and random. Deterministic (regular) failures are the result of defects in an object or system that were allowed in the design or manufacture of equipment, and the incompleteness or unpreparedness of the operator. Deterministic (regular) failures are characterized by the fact that, when establishing their true cause, they are eliminated with sufficiently high efficiency. In the practice of flight operation, they include the corresponding refinement of aircraft, improving the professional skills of crew members.

Random - these are system failures caused by random factors. Preventing accidental failures is difficult. This is due to the need for a wide range of measures for their forecasting and prevention.