Quantitative evaluation method for residual life echelon condition of fleet

Abstract

The invention provides a method for quantitatively evaluating the residual life echelon condition of an aircraft group based on an optimal echelon difference rate. The method comprises the following steps of: collecting and sorting data of residual life and specified life of a stage of each aircraft; calculating the actual residual life ratio K of the group; according to the value of K, determining the corresponding optimal echelon under the condition that the remaining life of the cluster is not changed in two situations; calculating the difference value between the actual residual life of each airplane and the residual life of the corresponding airplane in the optimal echelon; calculating the optimal echelon difference rate CP of the aircraft; and carrying out quantitative evaluation on the residual life echelon condition of the cluster based on the CP value. The method changes the defects of time and labor waste, lack of uniformity and the like based on an aircraft residual life echelon graph, overcomes the defects of complex calculation process, weak interpretability and the like in an evaluation method based on residual life echelon value variance and residual life echelon distribution uniformity, has the advantages of simplicity and convenience in calculation, easiness in understanding, wide application scene and the like, and is suitable for popularization and application. And a foundation is laid for carrying out airplane group residual life echelon condition evaluation, airplane group use control and the like.

Description

Technical Field

[0001] This invention relates to aircraft fleet operation control technology, specifically to a method for quantitatively assessing the remaining lifespan and status of an aircraft fleet. Background Technology

[0002] When an aircraft reaches a certain service life, it requires major overhaul. An aircraft overhaul is a comprehensive repair performed according to technical standards and process requirements to restore the aircraft's performance. Major overhauls typically require the aircraft to be sent to a specialized overhaul facility and can take anywhere from several months to over ten months, or even several decades. During a major overhaul, the aircraft cannot perform flight missions.

[0003] When an aircraft leaves the factory or after a major overhaul, it is given a limit on the amount of time it can fly before the next major overhaul. This limit is called the "overhaul time limit" or "stage-defined life" (hereinafter referred to as "stage-defined life"). The amount of time an aircraft can fly before the overhaul time limit is called the "stage-remaining life," or simply "life remaining."

[0004] In managing the operation of an aircraft fleet, an organization should strive to stagger the timing of major aircraft overhauls and repairs. Otherwise, multiple aircraft may be undergoing major overhauls at the factory within a certain period, leading to a reduction in the number of available aircraft and severely impacting the completion of flight missions. Therefore, effective aircraft fleet operation control is crucial, and the key is to maintain a certain lifespan reserve while ensuring a reasonable lifespan hierarchy for the aircraft fleet. The lifespan hierarchy of an aircraft fleet refers to the remaining lifespan of the same type of aircraft within an organization at a given moment.

[0005] To achieve a good remaining life sequence of aircraft fleets, an accurate assessment of the remaining life sequence is required. Two methods are typically employed: one is based on an aircraft remaining life sequence chart, and the other is based on quantitative indicators.

[0006] 1. Aircraft lifespan gradation diagram

[0007] 1.1 Aircraft Lifespan Sequence Diagram

[0008] The aircraft lifespan gradation diagram is attached. Figure 1 As shown, the elements of this diagram are as follows:

[0009] (1) Two-dimensional coordinate system. The horizontal axis is the aircraft serial number (the serial number value corresponding to each aircraft after the remaining life of the aircraft is arranged from smallest to largest, starting from 1), and the vertical axis is the remaining life of the aircraft. In actual use, for ease of reading, the aircraft number can also be marked on the horizontal axis.

[0010] (2) Life Expectancy Bar Chart. A bar chart for each aircraft, with the height of the bars representing the remaining life of the corresponding aircraft. The bars are closely connected but do not overlap.

[0011] (3) Yu Shou Standard Line. The coordinates of the left endpoint of this line are (0,0), and the coordinates of the right endpoint are...

[0013] in,

[0014] N is the number of aircraft;

[0015] It is the average of the specified lifespan of each aircraft at each stage, i.e.

[0016] H 规i , is the stage-specified lifespan of the i-th (i = 1, ..., N) aircraft;

[0017] K 标准 The fleet life ratio, or simply "life ratio," is the ratio of the sum of the remaining lives of all aircraft to the sum of the stage-specific lifespans of all aircraft. The formula is:

[0018]

[0019] Among them, H i This represents the remaining stage life of the i-th (i = 1, ..., N) aircraft.

[0020] K 标准 As stipulated by the aircraft management department, it is usually no more than 50%, with a typical value of 40%. The purpose of setting the fleet life ratio is to ensure that the aircraft fleet maintains a certain reserve life to prepare for the need to deplete the aircraft's lifespan in case of emergencies.

[0021] 1.2 Assessment of the tiered status based on the aircraft's remaining service life tiered chart

[0022] By analyzing the relationships between the remaining life bars and life standard lines of each aircraft on the aircraft life tier chart, a judgment can be made on the life tier status of the aircraft fleet.

[0023] (1) If the top of the bar chart corresponding to each aircraft is near the intersection of the corresponding serial number of the aircraft and the lifespan standard line, then the lifespan tier of the aircraft group is relatively good.

[0024] (2) If the top of the bar chart corresponding to an aircraft is far from the intersection of the aircraft's corresponding serial number and the lifespan standard line, then the lifespan tiering of the fleet is not good enough. The more aircraft there are and the greater the distance between them, the worse the tiering situation becomes.

[0025] For example, appendix Figure 2 (a) has a better fleet lifespan distribution than the attached fleet. Figure 2 (b) The remaining lifespan of the fleet.

[0026] The aircraft life tiered condition assessment method based on the aircraft life tiered chart has the advantage of being highly intuitive, but the process of drawing the aircraft life tiered chart is time-consuming and labor-intensive. The results of the chart need to be interpreted manually, and the interpretation results may vary from person to person. Moreover, the interpretation results are often qualitative descriptions of the tiered condition such as "good", "relatively good", "average" or similar, which are not convenient for subsequent quantitative processing.

[0027] 2. Quantitative evaluation indicators

[0028] Methods for quantitatively assessing the remaining life of aircraft fleets include indicators such as variance of remaining life tier values ​​and uniformity of remaining life tiers in relevant literature.

[0029] (1) Variance of the life ladder value

[0030] Yang Weixin proposed this indicator in his paper "Research on Quantitative Methods for Macro Management of Aviation Equipment". The basic idea is to calculate the ladder value of each aircraft; obtain the weighted average ladder value of the aircraft group; and calculate the variance of the ladder value of each aircraft.

[0031] The aircraft life gradient value reflects the average trend of the aircraft lifespan arrangement, and its value is the aircraft lifespan t. i The ratio of its index i to that of its index i is denoted as T. zai The calculation formula is:

[0032]

[0033] Aircraft life ladder variance D a This indicates the deviation between the aircraft's remaining service life and the average service life of the aircraft (or the arithmetic progression of the aircraft's remaining service life). The calculation formula is as follows:

[0034]

[0035] Among them, weighted life ladder value

[0036] By analyzing D a The value of D is used to assess the remaining lifespan of the fleet. a If the value is 0, then the remaining lifespan of the aircraft forms an arithmetic sequence, indicating that the lifespan hierarchy of the fleet is in good condition; otherwise, an arithmetic sequence has not been formed, D a The larger the value, the worse the remaining lifespan of the fleet.

[0037] (2) Uniformity of lifespan gradient

[0038] In his paper "Exploration and Reflection on the Gradual Control of Aircraft Lifespan", Yuan Hui proposed the concept of "gradual uniformity of lifespan", which was cited and applied by Liu Qing and others.

[0039] The uniformity of remaining service life, Q, is used to evaluate the uniformity of the remaining service life sequence of an aircraft at a certain moment. Its calculation formula is as follows:

[0040]

[0041] Among them, ideal interval

[0042] A higher Q value indicates a better sequence condition. The Q value is the largest, at 100%, when the remaining service life of each aircraft is equal to the ideal interval Δ. When the remaining service life of each aircraft is exactly the same, the Q value is 0, which indicates the worst sequence condition.

[0043] 3. The need for quantitative assessment methods for the remaining life status of aircraft.

[0044] In summary, the aircraft life tiering method is time-consuming and labor-intensive, lacks quantitative evaluation rules, and is not well-suited for scenarios such as comparing the life tiering status of aircraft fleets across different organizations. Some studies combine aircraft life tiering assessment with other related work, which has some practicality, but it is difficult to accurately examine the life tiering status of an aircraft fleet.

[0045] Meanwhile, the two quantitative indicators, the variance of the remaining life ladder and the uniformity of the remaining life ladder, have clear calculation rules and quantifiable calculation results, but their interpretability is weak.

[0046] Therefore, it is necessary to study a quantitative assessment method for the remaining lifespan of an aircraft fleet to provide strong methodological support for aircraft use control, aircraft use planning, and ultimately, the rational use of aircraft. Summary of the Invention

[0047] To address the problems existing in the prior art, this invention provides a method for quantitatively assessing the remaining service life of an aircraft fleet, specifically including the following steps:

[0048] Step 1: Collect and organize data on the remaining service life and stage-specified service life of each aircraft;

[0049] Collect the remaining life data of each aircraft and arrange them in ascending order of remaining life to form a sequence;

[0050] Assume the unit has N aircraft in service; arrange the remaining lifespan of the aircraft from smallest to largest, forming t1, t2, ..., t N The sequence; where t i For the remaining lifespan of the i-th aircraft, 1 ≤ i ≤ N;

[0051] Step 2: Actual remaining lifetime ratio K of the computer cluster;

[0052] Step 2.1: Sum of the remaining lifespan of the computer cluster t ;

[0053] Sum of remaining lifespan of the aircraft group t for:

[0054]

[0055] Step 2.2: The sum of the lifetimes S defined in the computer cluster phase H ;

[0056] The sum of the specified lifespans of the fleet phase S H for:

[0057]

[0058] Among them, H i Define the stage life for the i-th aircraft;

[0059] Step 2.3: Actual remaining lifetime ratio K of the computer cluster;

[0060] The actual remaining life ratio K of the fleet is:

[0061]

[0062] Right now,

[0063] Step 3: Determine the optimal tier when the total remaining life of the fleet remains unchanged, based on the value of K in two cases;

[0064] Distinguish between the two possible values ​​of K to determine the corresponding optimal tier;

[0065] Case 1: K ≤ 50%

[0066] At this point, the optimal gradient line and the horizontal and vertical coordinate axes form a triangle, and the area S1 of the triangle is:

[0067]

[0068] Among them, H 右端点 This represents the height of the "optimal ladder line" at position N on the horizontal axis.

[0069] According to the definition of the remaining life ratio K, we have:

[0070]

[0071] in, It is the average of the specified lifespan of each aircraft at each stage, i.e.

[0072] H 规i , is the stage-defined lifespan of the i-th aircraft, i = 1, ..., N;

[0073] thus,

[0074] Based on the principle of similarity, the remaining life of the i-th aircraft under the optimal tier configuration is obtained. for:

[0075]

[0076] Scenario 2: K > 50%

[0077] The height of the left endpoint of the "optimal ladder line" is H. 左端点 The optimal gradient line, along with the horizontal and vertical axes, forms a trapezoid. The area S2 of this trapezoid is:

[0078]

[0079] have:

[0080]

[0081] but

[0082] Based on the principle of similarity, the remaining life of the i-th aircraft under the optimal tier configuration is obtained.

[0083]

[0084] Summarized as follows:

[0085]

[0086] Step 4: Calculate the difference between the actual remaining life of each aircraft and the remaining life of the corresponding aircraft in the optimal sequence;

[0087] Let C be the absolute value of the difference between the actual remaining life of the i-th aircraft and the remaining life of the aircraft corresponding to the optimal sequence number. i ;

[0088]

[0089] Step 5: Calculate the optimal aircraft tier difference rate C P ;

[0090] Step 5.1: Summarize the optimal aircraft tier difference S c ;

[0091] Summarize the optimal tier difference S of aircraft c for:

[0092]

[0093] Step 5.2: Calculate the optimal ladder difference C P ;

[0094] Optimal tier difference C P for:

[0095]

[0096] Step 6: Based on C P The remaining service life of the fleet is quantitatively assessed.

[0097] 6.1 Evaluation Rules;

[0098] C P The smaller the value, the better the aircraft's remaining lifespan; conversely, the larger the value, the worse. P The minimum value is 0, which indicates that the remaining life of each aircraft is in the optimal tiered condition.

[0099] 6.2 Typical evaluation scenarios;

[0100] Scenario 1: Assessment of the status of a unit's aircraft tiers;

[0101] Calculate C P Value, through C P The value provides a quantitative evaluation result of the status of a single aircraft tier.

[0102] Scenario 2: Comparison of aircraft tier status at different times within a single unit;

[0103] The corresponding C was calculated based on the aircraft tier status at different times within the same unit. P value;

[0104] If C P A smaller value indicates that the remaining lifespan of the aircraft in that unit is improving.

[0105] If C P The value remains unchanged, indicating that the remaining lifespan of the aircraft in this unit has remained basically unchanged.

[0106] If C P An increase in the value indicates that the remaining lifespan of the aircraft in that unit is deteriorating.

[0107] Scenario 3: Comparison of aircraft tiers between different units;

[0108] Directly to two units of C P Compare;

[0109] The first unit of C P The value is C P1 The second unit value of C P The value is C P2 ;

[0110] If C P1 <C P2 This indicates that the remaining lifespan of the aircraft in the first unit is better than that of the second unit.

[0111] If C P1 =C P2 This indicates that the remaining lifespan of the aircraft in the first unit is basically the same as that in the second unit;

[0112] If C P1 >C P2 This indicates that the remaining lifespan of the aircraft in the first unit is worse than that of the second unit.

[0113] This invention determines the optimal tier corresponding to the actual remaining life ratio of an aircraft fleet to be evaluated, calculates the difference between the remaining life of each aircraft in the current fleet and the remaining life of the corresponding aircraft in the optimal tier, and normalizes this difference using the number of aircraft and the stage-defined lifespan to obtain the optimal tier difference rate index. The optimal tier difference rate is simple to calculate, highly interpretable, and highly comparable. Based on the optimal tier difference rate, it is possible to quantitatively compare the remaining life tier status of aircraft in different units, fleets of different sizes, and with different average stage-defined lifespans. Attached Figure Description

[0114] Figure 1 A schematic diagram showing the aircraft's remaining life tiered chart;

[0115] Figure 2 This shows a typical aircraft life tier diagram, in which... Figure 2 (a) shows a case where the tiered structure is relatively good. Figure 2 (b) shows a situation where the tiered structure is poor;

[0116] Figure 3 A flowchart is shown for a method to quantitatively assess the fleet lifespan status of aircraft based on the optimal aircraft tier difference rate.

[0117] Figure 4 The diagram illustrates the determination of the optimal aircraft sequence based on the K value, where... Figure 4 (a) Shows the tiered status where the actual remaining life ratio K of the fleet is less than or equal to 50%; Figure 4 (b) shows the optimal ladder corresponding to Figure a; Figure 4 (c) Shows the tiered status where the actual remaining life ratio K of the fleet is greater than 50%; Figure 4 (d) shows the optimal ladder corresponding to Figure c;

[0118] Figure 5 C is shown i A schematic diagram of the calculation. Detailed Implementation

[0119] The present invention will now be described in detail with reference to the accompanying drawings.

[0120] This invention provides a method for quantitatively assessing the remaining lifespan and tiered status of an aircraft fleet. The overall process is as follows: Figure 3 As shown, the details are as follows.

[0121] Step 1: Collect and organize data on the remaining service life and stage-specified service life of each aircraft;

[0122] Collect the remaining life data of each aircraft and arrange them in ascending order of remaining life to form a sequence.

[0123] Assume the unit has N aircraft in its fleet. Arrange the remaining lifespan of the aircraft in ascending order, forming t1, t2, ..., t N The sequence. Where t i (1 ≤ i ≤ N) represents the remaining lifespan of the i-th aircraft.

[0124] Step 2: Actual remaining lifetime ratio K of the computer cluster;

[0125] Step 2.1: Sum of the remaining lifespan of the computer cluster t ;

[0126] Fleet lifespan, which is the sum of the lifespans of each individual aircraft (S). t The calculation formula is:

[0127]

[0128] Step 2.2: The sum of the lifetimes S defined in the computer cluster phase H ;

[0129] The sum of the specified lifespans of the fleet phase S H This is the sum of the stage-specified lifespans of all aircraft in a unit. The calculation formula is:

[0130]

[0131] Among them, H i The stage-defined lifespan of the i-th aircraft.

[0132] Step 2.3: Actual remaining lifetime ratio K of the computer cluster;

[0133] The fleet's actual remaining life ratio K is the ratio of the sum of the stage remaining lifespans of all aircraft in the fleet to the total stage-specified lifespan. It represents the proportion of an aircraft's average stage-specified lifespan, and the calculation formula is as follows:

[0134]

[0135] Based on the aforementioned calculation formula, there is also

[0136] Step 3: Determine the optimal tier when the total remaining life of the fleet remains unchanged, based on the value of K in two cases;

[0137] By distinguishing between the two possible values ​​of K, the optimal tier can be determined.

[0138] The term "optimal tiering" refers to the optimal remaining lifespan of an aircraft fleet, assuming the total remaining lifespan remains constant. In optimal tiering, the remaining lifespans of each aircraft form an arithmetic sequence, and the common difference of this sequence should be as large as possible. The principle of optimal tiering is illustrated in the appendix. Figure 4 As shown.

[0139] Case 1: K≤50%

[0140] When K ≤ 50%, the shape formed by the optimal gradient line and the horizontal and vertical coordinate axes is a triangle, as shown in the attached figure. Figure 4 As shown in (b).

[0141] The area S1 of the triangle is:

[0142]

[0143] Among them, H 右端点 This is the height value of the "optimal ladder line" at position N on the horizontal axis (the height of the right endpoint).

[0144] According to the definition of the remaining life ratio K, we have:

[0145]

[0146] thus, That is, the height value of the "optimal ladder line" at position N on the horizontal axis (the height of the right endpoint) is

[0147] After determining the "optimal tier line", the remaining life of the i-th aircraft under the optimal tier condition can be obtained according to the similarity principle (which is well known to those skilled in the art). for:

[0148]

[0149] Scenario 2: K > 50%

[0150] When the fleet life ratio K > 50%, the maximum lifespan of each aircraft cannot exceed the actual limit of the aircraft's stage-specific lifespan. Therefore, the right endpoint of the "optimal ladder line" can only be located at... It cannot rise any further. At this point, the left endpoint needs to be raised from the origin (0,0), meaning its left endpoint height is H. 左端点 The optimal gradient line, along with the horizontal and vertical axes, forms a trapezoid. (See attached diagram.) Figure 4 As shown in (d), the area S2 of the trapezoid is:

[0151]

[0152] According to the definition of the aircraft fleet life ratio K, we also have:

[0153]

[0154] but

[0155] Based on the principle of similarity, the remaining life of the i-th aircraft under the optimal tier configuration can be obtained.

[0156]

[0157] Summarized as follows:

[0158]

[0159] Step 4: Calculate the difference between the actual remaining life of each aircraft and the remaining life of the corresponding aircraft in the optimal sequence;

[0160] Let C be the absolute value of the difference between the actual remaining life of the i-th aircraft and the remaining life of the aircraft corresponding to the optimal sequence number. i Taking the absolute value avoids the possibility of positive and negative differences between different aircraft canceling each other out during aggregation. C i The calculation process is as follows: Figure 5 As shown, its calculation formula is:

[0161]

[0162] Step 5: Calculate the optimal aircraft tier difference rate C P ;

[0163] Step 5.1: Summarize the optimal aircraft tier difference S c ;

[0164] Sum of the differences in the optimal aircraft hierarchy c The calculation formula is:

[0165]

[0166] Step 5.2: Calculate the optimal ladder difference C P ;

[0167] Calculate the optimal gradient difference C P The calculation formula is:

[0168]

[0169] In reality, it's the product of the aircraft's average stage life and the number of aircraft, divided by S. cThe aim is to eliminate the influence of the number of aircraft and the average stage specified life, so that the quantitative assessment of the tiered status under different units, different fleet sizes, and different average stage specified lifespans can make the results comparable.

[0170] C P The meaning is: on average, the ratio of the difference between the remaining life of each aircraft and the remaining life of the corresponding aircraft in the optimal tier corresponding to the current aircraft fleet's remaining life, to the average stage-defined life of the fleet.

[0171] If the average phase life of an aircraft is specified as 1000 flight hours, then at a certain moment C... P If it is 1%, it means that, on average, the remaining life of each aircraft at this unit at this moment differs from the remaining life of the aircraft in the corresponding optimal tier by 1000 × 1% hours, or 10 hours.

[0172] Step 6: Based on C P The remaining service life of the fleet is quantitatively assessed.

[0173] 6.1 Evaluation Rules;

[0174] C P It reflects, on average, the ratio of the remaining life difference between each aircraft and its corresponding optimal tier to the average specified stage life.

[0175] C P The smaller the value, the better the aircraft's remaining lifespan; conversely, the larger the value, the worse. C P The minimum value is 0, which indicates that the remaining life of each aircraft is in the optimal tiered condition.

[0176] Based on the above rules, the remaining lifespan of a unit's fleet can be quantitatively assessed; or the remaining lifespan of two or more units can be quantitatively compared.

[0177] 6.2 Typical evaluation scenarios;

[0178] Scenario 1: Assessment of the status of a unit's aircraft tiers.

[0179] Calculate C P Value, through C P The value provides a quantitative evaluation result of the status of a single aircraft tier.

[0180] Scenario 2: Comparison of aircraft tier status at different times within a single unit.

[0181] For the same unit, the aircraft tier status at different times can be calculated separately to obtain the corresponding C. P value.

[0182] If C PA smaller value indicates that the remaining lifespan of the aircraft in that unit is improving.

[0183] If C P If the value remains unchanged, it means that the remaining lifespan of the aircraft in that unit has remained basically unchanged.

[0184] If C P An increase in the value indicates that the remaining lifespan of the aircraft in that unit is deteriorating.

[0185] Scenario 3: Comparison of aircraft tiers between different units.

[0186] For different units, because C P In the value calculation, the influence of the average stage specified life and aircraft size was eliminated, so the C values ​​of the two units were directly calculated. P Compare them.

[0187] That is, the first unit of C P The value is C P1 The second unit value of C P The value is C P2 .

[0188] If C P1 <C P2 This indicates that the remaining lifespan of the aircraft in the first unit is better than that of the second unit.

[0189] If C P1 =C P2 This indicates that the remaining lifespan of the aircraft in the first unit is basically the same as that in the second unit;

[0190] If C P1 >C P2 This indicates that the remaining lifespan of the aircraft in the first unit is worse than that of the second unit.

[0191] This invention, by determining the optimal tier under the condition that the remaining life of the aircraft fleet remains unchanged, and measuring the difference between the actual remaining life and the remaining life of the aircraft corresponding to the optimal tier, represents the remaining life tier status of the aircraft fleet using the optimal tier difference rate. This invention overcomes the shortcomings of time-consuming and labor-intensive methods based on aircraft remaining life tier charts, which lack uniformity, and the shortcomings of assessment methods based on the variance of remaining life tier values ​​and uniform distribution of remaining life tiers, which have complex calculation processes and weak interpretability. It has the advantages of simple calculation, easy understanding, and wide applicability, laying the foundation for the assessment of the remaining life tier status of the aircraft fleet and the control of aircraft fleet use.

Claims

1. A method for quantitatively assessing the tiered status of fleet lifespan, characterized in that, Specifically, the following steps are included: Step 1: Collect and organize data on the remaining service life and stage-specified service life of each aircraft; Collect the remaining life data of each aircraft and arrange them in ascending order of remaining life to form a sequence; Assume the unit has N aircraft in service; arrange the remaining lifespan of the aircraft from smallest to largest, forming t1, t2, ..., t N The sequence; where t i For the remaining lifespan of the i-th aircraft, 1 ≤ i ≤ N; Step 2: Actual remaining lifetime ratio K of the computer cluster; Step 2.1: Sum of remaining lifespan of the computer cluster t ; Sum of remaining lifespan of the aircraft group t for: Step 2.2: The sum of the lifetimes S defined in the computer cluster phase H ; The sum of the lifespans specified in the fleet phase is: Among them, H i Define the stage life for the i-th aircraft; Step 2.3: Actual remaining lifetime ratio K of the computer cluster; The actual remaining life ratio K of the fleet is: Right now, Step 3: Determine the optimal tier when the total remaining life of the fleet remains unchanged, based on the value of K in two cases; Distinguish between the two possible values ​​of K to determine the corresponding optimal tier; Case 1: K ≤ 50% At this point, the optimal gradient line and the horizontal and vertical coordinate axes form a triangle, and the area S1 of the triangle is: Among them, H 右端点 This represents the height of the "optimal ladder line" at position N on the horizontal axis. According to the definition of the remaining life ratio K, we have: in, It is the average of the specified lifespan of each aircraft at each stage, i.e. H 规i , is the stage-defined lifespan of the i-th aircraft, i = 1, ..., N; thus, Based on the principle of similarity, the remaining life of the i-th aircraft under the optimal tier configuration is obtained. for: Scenario 2: K > 50% The height of the left endpoint of the "optimal ladder line" is H. 左端点 The figure enclosed by the optimal tier line, the horizontal axis, and the vertical axis is a trapezoid, and the area S2 of this trapezoid is; have: but Based on the principle of similarity, the remaining life of the i-th aircraft under the optimal tier configuration is obtained. Summarized as follows: Step 4: Calculate the difference between the actual remaining life of each aircraft and the remaining life of the corresponding aircraft in the optimal sequence; Let C be the absolute value of the difference between the actual remaining life of the i-th aircraft and the remaining life of the aircraft corresponding to the optimal sequence number. i ; Step 5: Calculate the optimal aircraft tier difference rate C P ; Step 5.1: Summarize the optimal aircraft tier difference S c ; Summarize the optimal tier difference S of aircraft c for: Step 5.2: Calculate the optimal ladder difference C P ; Optimal tier difference C P for: Step 6: Based on C P The remaining service life of the fleet is quantitatively assessed. 6.1 Evaluation Rules; C P The smaller the value, the better the aircraft's remaining lifespan; conversely, the larger the value, the worse. P The minimum value is 0, which indicates that the remaining life of each aircraft is in the optimal tiered condition. 6.2 Typical evaluation scenarios; Scenario 1: Assessment of the status of a unit's aircraft tiers; Calculate C P Value, through C P The value provides a quantitative evaluation result of the status of a single aircraft tier. Scenario 2: Comparison of aircraft tier status at different times within a single unit; The corresponding C was calculated based on the aircraft tier status at different times within the same unit. P value; If C P A smaller value indicates that the remaining lifespan of the aircraft in that unit is improving. If C P The value remains unchanged, indicating that the remaining lifespan of the aircraft in this unit has remained basically unchanged. If C P An increase in the value indicates that the remaining lifespan of the aircraft in that unit is deteriorating. Scenario 3: Comparison of aircraft tiers between different units; Directly to two units of C P Compare; The first unit of C P The value is C P1 The second unit value of C P The value is C P2 ; If C P1 <C P2 This indicates that the remaining lifespan of the aircraft in the first unit is better than that of the second unit. If C P1 =C P2 This indicates that the remaining lifespan of the aircraft in the first unit is basically the same as that in the second unit; If C P1 >C P2 This indicates that the remaining lifespan of the aircraft in the first unit is worse than that of the second unit.

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