Method and apparatus for aircraft low utilization maintenance interval conversion

Abstract

The application provides a method and device for converting maintenance intervals of an aircraft in low utilization, comprising the following steps: S1, obtaining an aircraft maintenance outline; S2, determining the number of months to be counted and counting the utilization of the aircraft; S3, predicting the low utilization of the aircraft; S4, converting the maintenance task intervals, including screening the maintenance tasks whose maintenance interval units are not calendar days; judging the importance of the maintenance tasks and performing conversion calculation of the maintenance task intervals; and S5, summarizing new maintenance tasks. The device comprises a database, an aircraft utilization counting module, a low utilization predicting module, a maintenance task converting module and a maintenance task output module, wherein the maintenance task converting module comprises a screening module, a weight module and a converting module. The application directly adopts the maintenance interval conversion method for unimportant maintenance tasks, reduces the number and complexity of reliability-centered maintenance analysis tasks, and can quickly obtain the maintenance tasks and their maintenance intervals under low utilization.

Description

Technical Field

[0001] This invention relates to the field of aircraft maintenance engineering, and more particularly to a method and apparatus for switching maintenance intervals when aircraft are underutilized. Background Technology

[0002] Typically, aircraft preventative maintenance tasks and their intervals are determined through Reliability-Centered Maintenance Analysis (RCMA) based on their expected utilization rates. In developing aircraft preventative maintenance tasks, the applicable aircraft utilization range is clearly defined in both the Policy and Procedure Manual (PPH) and the maintenance program. For example, the Boeing B747-400 maintenance program applies to an aircraft utilization range of 440 to 1320 FC / 1500 to 5500 FH per year, while the Airbus A330-200 maintenance program applies to an aircraft utilization range of 367 to 1100 FC / 1677 to 5667 FH per year. Within a given utilization range, preventative maintenance tasks maintain the aircraft's inherent levels of safety, reliability, and economy.

[0003] Low utilization is defined as the actual utilization rate of an aircraft operated by an aircraft user (such as an airline) falling below the prescribed minimum utilization rate. Continued operation under these conditions can lead to several problems: water vapor accumulation (e.g., in sound-absorbing and flame-retardant insulation materials, structural water drainage systems, etc.); reduced lubrication efficiency of lubricating oils or greases; potential chemical decomposition of lubricating oils or greases; aging of system or component seals, resulting in leaks of fuel, lubricating oil, etc.; internal corrosion of structures, power units, and components; corrosion affecting control cables and mechanisms; water vapor accumulation in the aircraft's structural water drainage system, rendering it inoperable; water accumulation in the fuel system, fostering microbial growth and sedimentation; and reduced reliability of electronic or electrical components due to prolonged inactivity or power outages, all of which can affect the aircraft's airworthiness. Therefore, under low utilization conditions, aircraft users should utilize low utilization condition maintenance procedures. However, due to limited understanding of the aircraft's technical specifications by the user, technical services and support from the manufacturer are required, specifying low utilization maintenance procedures and intervals.

[0004] Existing technologies typically employ reliability-centered maintenance analysis to identify low-utilization maintenance tasks and their intervals. However, in the aviation field, maintenance tasks are numerous and vary in importance. Applying reliability-centered maintenance analysis to all of them would be extremely complex. If maintenance intervals for a portion of maintenance tasks could be quickly determined under utilization conditions without relying on reliability-centered maintenance analysis, the complexity of reliability-centered maintenance analysis could be reduced, and low-utilization maintenance tasks and their intervals could be identified more quickly.

[0005] Moreover, the occurrence of low utilization is uncertain, and the degree of deviation from normal utilization is also uncertain. In this case, if a predictive method can be adopted based on the actual operating conditions, it is possible to determine when low utilization will occur and to obtain the degree of deviation from normal utilization, so as to better calculate maintenance task intervals and reduce costs and operational risks. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide maintenance tasks and maintenance intervals under low utilization conditions as quickly as possible. This invention provides a method for switching maintenance intervals when an aircraft is under low utilization, characterized by the following steps:

[0007] S1, Obtain the aircraft maintenance outline;

[0008] The aircraft maintenance program database is a data storage method for aircraft maintenance programs. The aircraft maintenance program database includes at least the aircraft normal utilization rate range, all aircraft maintenance tasks, failure impact of maintenance objects, maintenance object types, maintenance task types of maintenance objects, maintenance interval values ​​for maintenance tasks, and maintenance interval units for maintenance tasks.

[0009] S2. Determine the number of months requiring statistics and conduct aircraft utilization rate statistics:

[0010] Based on aircraft C-check or base-level maintenance intervals (I) C-check The minimum number of consecutive calendar months that need to be counted is:

[0011] n = [I C-check -1] (1)

[0012] Among them, I C-check This represents the number of C-checks or base-level maintenance intervals for aircraft, in months; n is the minimum number of consecutive calendar months to be counted.

[0013] Based on the number of calendar days n of the previous k-th month. day,k And the cumulative flight hours n in the current month fhm,k The monthly utilization rate for the first k months, expressed in flight hours, was obtained. for:

[0014]

[0015] Where, n fhm,k Let k be the cumulative flight hours for the first k months, where k = 1, 2, ..., n;

[0016] S3, Prediction of Low Aircraft Utilization:

[0017] Based on the monthly utilization statistics of the previous n months, the GM(1,1) model of the grey model is used to predict the monthly utilization rate for the (n+1)th month.

[0018] if The following conditions must be met

[0019]

[0020] Then, the maintenance task is switched, and step S4 is executed, where u fh-low This is the lower limit of the annual utilization rate;

[0021] S4, Maintenance Task Interval Switching:

[0022] S41 uses a selection criteria from the maintenance program database to identify maintenance tasks R whose maintenance interval units are engine replacement hours, APU hours, flight hours, and flight cycles. h h = 1, 2, ..., N, where N is the number of maintenance tasks obtained through screening;

[0023] S42, Determine maintenance task R h The importance of this, and the specific steps are as follows:

[0024] Calculate the importance factor s of the maintenance task.

[0025] s = s1 + s2 + s3 (14)

[0026] Wherein, s1 is the failure impact factor, s2 is the type factor, s3 is the task type factor, and s is the importance factor;

[0027] Determine the importance factor s. If s ≥ 8, then the importance of maintenance task R is high. h Conduct a reliability-centered maintenance analysis. If s < 8, then execute step S43 for maintenance task R. h Perform the conversion between maintenance interval values ​​and time units;

[0028] S43. Maintenance task interval conversion calculation:

[0029] First, the numerical conversion method for maintenance task intervals is as follows:

[0030] Based on the monthly utilization statistics sequence of the previous n months, U (0) The average monthly utilization rate u is obtained by combining the monthly utilization rate predicted in step S3 for month n+1.

[0031]

[0032] Obtain maintenance tasks from the aircraft maintenance syllabus. hThe maintenance interval value I0 is obtained from equation (16) as follows: The maintenance interval value I1 under low utilization is...

[0033]

[0034] Repair task R h The maintenance interval unit is directly changed to a month, resulting in maintenance task R. h The numerical value of the maintenance interval and the unit of the maintenance interval are I1 and month, respectively.

[0035] Determine whether all maintenance tasks that need to be converted have been converted. If yes, proceed to step S5; otherwise, return to step S42 and continue to convert the next maintenance task.

[0036] S5: Compile new maintenance tasks

[0037] The results of step S42, which involve converting maintenance task intervals, are summarized to form new maintenance requirements, which are then marked as applicable to low utilization rates.

[0038] Preferably, in the aircraft maintenance outline in S1, the failure impact factors of the maintenance object are classified into five categories: obvious safety, obvious mission-related, obvious economic, hidden safety, and hidden non-safety; the maintenance object type factors are divided into three categories: mechanical, electrical, and electronic; the maintenance task type factors of the maintenance object are divided into seven categories: SV / LU, VC / OP, GVI, DET, SDI, FNC, and RS / DI; and the maintenance interval units used for maintenance tasks include: engine replacement hours, APU hours, flight hours, flight cycles, and calendar days.

[0039] Preferably, the specific values ​​of the failure impact factor s1, type factor s2, and task type factor s3 in S42 are as follows:

[0040] The value of the failure impact factor s1 is determined based on the failure impact of the maintenance object. Specifically, when the failure impact is "obvious safety", s1 = 3; when the failure impact is "obvious task-related" or "hidden non-safety", s1 = 2; when the failure impact is "obvious economic", s1 = 1; and when the failure impact is "hidden safety", s1 = 4.

[0041] The value of the type factor s2 is determined based on the type of the object being repaired: s2 = 3 when the type is "mechanical"; s2 = 2 when the type is "electrical"; and s2 = 1 when the type is "electronic".

[0042] The value of the task type factor s3 is determined based on the maintenance task type of the maintenance object, specifically as follows: s3 = 1 when the maintenance task type is "SV / LU"; s3 = 2 when the maintenance task type is "VC / OP"; s3 = 3 when the maintenance task type is "GVI"; s3 = 4 when the maintenance task type is "DET"; s3 = 5 when the maintenance task type is "SDI"; s3 = 6 when the maintenance task type is "FNC"; and s3 = 7 when the maintenance task type is "RS / DI".

[0043] This invention also discloses an aircraft low-utilization maintenance interval conversion device, including a database, an aircraft utilization statistics module, a low-utilization prediction module, a maintenance task conversion module, and a maintenance task output module, specifically:

[0044] The database includes an aircraft maintenance program database and a flight database; the aircraft maintenance program database is a digitized storage of aircraft maintenance programs; the flight database stores the aircraft's flight records.

[0045] The aircraft utilization statistics module is used to generate monthly utilization statistics data sequences, based on aircraft C-check or base-level maintenance intervals. C-check Using formula (1), we obtain the minimum number of consecutive calendar months n that need to be counted, and retrieve the cumulative flight hours n for the current month based on the k-th month from the flight database. fhm,k The monthly utilization rate of the first k months is obtained according to formula (2). The monthly utilization rate of the first n months Arranged in order, the monthly utilization statistics data sequence for the first n months is given as U. (0) ;

[0046] The low utilization prediction module is used to determine whether the maintenance task switching module needs to be activated, and receives U data from the aircraft utilization statistics module. (0) The predicted monthly utilization rate for the (n+1)th month is obtained using the GM(1,1) model function module of the grey model. Retrieved from the aircraft maintenance syllabus database fh-low The operation ends if the condition is not met, and if the condition is met, a start signal is sent to the maintenance task conversion module to start the maintenance task conversion module.

[0047] The maintenance task conversion module is used to convert maintenance tasks with maintenance intervals measured in engine replacement hours, APU hours, flight hours, or flight cycles into calendar-day maintenance tasks with low utilization rates. It includes a filtering module, a weighting module, and a conversion module, specifically:

[0048] After receiving the start signal from the low utilization prediction module, the maintenance task conversion module first uses the filtering module to select maintenance tasks R from the aircraft maintenance outline database whose maintenance interval units are engine replacement hours, APU hours, flight hours, and flight cycles. h ;

[0049] The weighting module calculates the maintenance task R according to formula (14). h The importance factor s, if s≥8, is important for maintenance task R. h No operation is performed; if s < 8, then maintenance task R is performed. h Send to the conversion module; use the weighting module to send all maintenance tasks R with s < 8. h Send to the conversion module;

[0050] The conversion module converts maintenance task intervals under normal utilization into maintenance task intervals under low utilization. It first receives data from the aircraft utilization statistics module. (0) Receive the monthly utilization rate for month n+1 from the low utilization prediction module. The average monthly utilization rate u is obtained using formula (15), and the maintenance task R is obtained from the aircraft maintenance outline database. h The maintenance interval value I0 is obtained from equation (16), and the maintenance interval value I1 under low utilization is obtained from the maintenance task R. h The maintenance interval unit is directly changed to a month. It checks whether all maintenance tasks with an importance factor s < 8 have completed the conversion; otherwise, it continues the conversion; otherwise, it sends the conversion results of all maintenance tasks to the maintenance task output module.

[0051] The maintenance task output module is used to receive the conversion results of maintenance tasks from the maintenance task conversion module and output them. The converted maintenance task R h The numerical value of the maintenance interval and the unit of the maintenance interval are I1 and month, respectively.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. This invention directly uses a maintenance interval conversion method for unimportant maintenance tasks, which eliminates the need for reliability-centered maintenance analysis. This greatly reduces the number and complexity of reliability-centered maintenance analysis tasks, and allows for faster acquisition of maintenance tasks and their maintenance intervals under low utilization.

[0054] 2. This invention changes the previous "fixed" maintenance tasks and interval requirements recommended for low utilization operation to "flexible" maintenance tasks and interval requirements that are closely aligned with actual operating conditions. This makes it more widely applicable, more flexible in method, and easier to operate in practice. Attached Figure Description

[0055] Figure 1 This is a flowchart of the aircraft low-utilization maintenance interval conversion method;

[0056] Figure 2 This is a diagram illustrating aircraft utilization.

[0057] Figure 3 This is a flowchart of the maintenance task interval switching steps:

[0058] Figure 4 This is a schematic diagram of a device for switching maintenance intervals when an aircraft is underutilized. Detailed Implementation

[0059] To better understand the technical solution of the present invention, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The same reference numerals in the drawings indicate elements with the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0060] This invention relates to a method for switching maintenance intervals when an aircraft is under low utilization, such as... Figure 1 As shown, the specific implementation steps are as follows:

[0061] S1, Obtain the aircraft maintenance outline.

[0062] The aircraft maintenance program includes various data used during aircraft maintenance. This invention utilizes data from the aircraft maintenance program database, including aircraft normal utilization range, failure impact of maintenance objects, maintenance object types, maintenance task types for maintenance objects, maintenance interval values ​​for maintenance tasks, and maintenance interval units for maintenance tasks. The aircraft maintenance program database is a data-driven storage method for aircraft maintenance programs.

[0063] In the aircraft maintenance syllabus, the Failure Impact Factors (FECs) of the maintenance object are classified into five categories: obvious safety, obvious mission-related, obvious economic, hidden safety, and hidden non-safety. The maintenance object type factors are divided into three categories: mechanical, electrical, and electronic. The maintenance task type factors are divided into seven categories: SV / LU (Lubrication / Service), VC / OP (Visual / Operational Inspection), GVI (General Visual Inspection), DET (Detailed Inspection), SDI (Special Detailed Inspection), FNC (Functional Inspection), and RS / DI (Restore / Disposal). Different maintenance tasks use different maintenance interval units, including: engine replacement hours, APU hours (Auxiliary Power Unit), flight hours, flight cycles, and calendar days.

[0064] S2. Determine the number of months requiring statistics and conduct aircraft utilization rate statistics:

[0065] Based on aircraft C-check or base-level maintenance intervals (I) C-check The minimum number of consecutive calendar months that need to be counted is:

[0066] n = [I C-check -1] (1)

[0067] Among them, I C-check The interval between aircraft C-checks or base-level maintenance is in months; n is the minimum number of consecutive calendar months to be counted, rounded to the nearest integer, i.e., a sequence of monthly utilization statistics data for at least the first n months is required.

[0068] Based on the number of calendar days n of the previous k-th month. day,k And the cumulative flight hours n in the current month fhm,k The monthly utilization rate for the first k months, expressed in flight hours, was obtained. for:

[0069]

[0070] Where, n fhm,k The cumulative flight hours for the current month of the k-th month are obtained from the flight database; k = 1, 2, ..., n;

[0071] Flight databases store aircraft flight records, typically including flight duration, number of flights, flight routes, and equipment data, among other flight-related information.

[0072] S3, Prediction of Low Aircraft Utilization:

[0073] Aircraft utilization rate refers to the number of operational flight hours (FH) or flight cycles (FC) provided by an aircraft within a certain period (year, month, or day). It reflects the degree of aircraft utilization from a time perspective. Figure 2 As shown, aircraft utilization is an important top-level parameter in the aircraft design process. It serves as an input for reliability and maintainability design and analysis, and also affects the formulation and execution of aircraft maintenance tasks.

[0074] The normal utilization rate in the aircraft maintenance program database falls within a certain range and satisfies the following:

[0075] u fh -l ow ≤u fh ≤u fh-up or u fc-low ≤u fc ≤u fc-up (3)

[0076] Among them, u fh-low It is the lower limit of annual utilization rate in flight hours, ufh-up This refers to the annual utilization rate cap in flight hours, or in flight cycles. fc-low This is the lower limit for the number of flight cycles per year, u fc-up The maximum number of flight cycles per year, u fh For actual annual utilization rate, u fc This represents the actual number of flight cycles per year.

[0077] Low utilization rate refers to the occurrence of:

[0078] u fh <u fh-low or u fc <u fc-low (4)

[0079] At this point, adjustments need to be made to the aircraft maintenance tasks, including the maintenance interval values ​​and units, in order to maintain the inherent safety and reliability of the aircraft.

[0080] This application uses the lower limit of annual utilization rate to determine whether a change in maintenance tasks is necessary.

[0081] Based on the monthly utilization rate statistics for the previous n months, the GM(1,1) model of the grey model is used to predict the monthly utilization rate for the (n+1)th month. The monthly utilization rate statistics sequence for the previous n months is U. (0) , means as follows:

[0082]

[0083] Among them, U (0) Let be the statistical data sequence of monthly utilization rates for the previous n months, where each element is the monthly utilization rate obtained according to formula (2).

[0084] After one accumulation, we get U. (1)

[0085]

[0086]

[0087] in, The summation value;

[0088] Establish the whitening differential equation

[0089]

[0090] Where a is the development coefficient and b is the grey effect quantity. The corresponding grey differential equation is...

[0091]

[0092] in

[0093]

[0094] Calculate the parameter vector using the least squares method

[0095] (a,b) T = (B T B) -1 BY (9)

[0096] in

[0097]

[0098]

[0099] The predicted value of the (n+1)th accumulated value

[0100]

[0101] Restore the forecast value for month n+1.

[0102]

[0103] In practical implementation, the monthly utilization rate statistical data sequence U is used. (0) Inputting the data into the GM(1,1) model function module of the existing grey model yields the predicted monthly utilization rate for the (n+1)th month. To achieve this.

[0104] Retrieve u from the aircraft maintenance syllabus database fh-low The lower limit of annual utilization rate u fh-low Divide the data equally over 12 months and calculate the average. The following conditions must be met

[0105]

[0106] Then, the maintenance task is switched, and step S4 is executed.

[0107] S4, Maintenance task interval switching, such as Figure 3 As shown:

[0108] S41 uses a conditional filtering method to select maintenance tasks R whose maintenance interval unit is not based on calendar days from the maintenance outline database. h h = 1, 2, ..., N, where N is the number of maintenance tasks with a maintenance interval unit other than calendar days.

[0109] S42, Determine maintenance task R h The importance of this, and the specific steps are as follows:

[0110] The value of the failure impact factor s1 is determined based on the failure impact of the maintenance object. Specifically, when the failure impact is "obvious safety", s1 = 3; when the failure impact is "obvious task-related" or "hidden non-safety", s1 = 2; when the failure impact is "obvious economic", s1 = 1; and when the failure impact is "hidden safety", s1 = 4.

[0111] The value of the type factor s2 is determined based on the type of the object being repaired: s2 = 3 when the type is "mechanical"; s2 = 2 when the type is "electrical"; and s2 = 1 when the type is "electronic".

[0112] The value of the task type factor s3 is determined based on the maintenance task type of the maintenance object, specifically as follows: s3 = 1 when the maintenance task type is "SV / LU"; s3 = 2 when the maintenance task type is "VC / OP"; s3 = 3 when the maintenance task type is "GVI"; s3 = 4 when the maintenance task type is "DET"; s3 = 5 when the maintenance task type is "SDI"; s3 = 6 when the maintenance task type is "FNC"; and s3 = 7 when the maintenance task type is "RS / DI".

[0113] Calculate the importance factor s of the maintenance task.

[0114] s = s1 + s2 + s3 (14)

[0115] Wherein, s1 is the failure impact factor, s2 is the type factor, s3 is the task type factor, and s is the importance factor.

[0116] Determine the importance factor s. If s ≥ 8, then the importance of maintenance task R is high. h Conduct a reliability-centered maintenance analysis. If s < 8, then execute step S43 for maintenance task R. h The maintenance interval values ​​are converted to time units. Reliability-centered maintenance analysis of maintenance tasks is existing technology and will not be elaborated upon in this embodiment.

[0117] S43. Maintenance task interval conversion calculation:

[0118] First, the numerical conversion method for maintenance task intervals is as follows:

[0119] Based on the monthly utilization statistics sequence of the previous n months, U (0) The average monthly utilization rate u is obtained by combining the monthly utilization rate predicted in step S3 for month n+1.

[0120]

[0121] Where m is a positive integer;

[0122] Retrieve maintenance tasks R from the aircraft maintenance syllabus databaseh The maintenance interval value I0 is obtained from equation (16) as follows: The maintenance interval value I1 under low utilization is...

[0123]

[0124] Repair task R h The maintenance interval unit has been changed to a month (MO), meaning that the original engine replacement hours, APU hours, flight hours, and flight cycles have all been changed to a month (MO).

[0125] At this time, maintenance task R h The numerical value of the maintenance interval and the unit of maintenance interval are I1 and month (MO), respectively.

[0126] Determine whether all maintenance tasks that need to be converted have been converted. If yes, proceed to step S5; otherwise, return to step S42 and continue to convert the next maintenance task.

[0127] S5: Compile new maintenance tasks

[0128] The results of step S42, which involve converting maintenance task intervals, are summarized to form new maintenance requirements, which are then marked as applicable to low utilization rates.

[0129] Furthermore, the summarized maintenance task interval conversion results, the maintenance analysis results centered on reliability, and the maintenance tasks with maintenance interval units in calendar days are combined to form a complete set of maintenance tasks and their maintenance intervals under low utilization.

[0130] The above method shows that it is still applicable to maintenance tasks with calendar days as the maintenance unit under low utilization. For maintenance tasks with an importance factor of s < 8, the present invention can be used to convert them to use calendar days as the maintenance unit. Only for maintenance tasks with an importance factor of s ≥ 8, reliability-centered maintenance analysis is carried out. This greatly reduces the number and complexity of reliability-centered maintenance analysis tasks and can obtain maintenance tasks and their maintenance intervals under low utilization more quickly.

[0131] The present invention also provides an aircraft low-utilization maintenance interval switching device, such as... Figure 4 As shown, it includes database 1, aircraft utilization statistics module 2, low utilization prediction module 3, maintenance task conversion module 4, and maintenance task output module 5, specifically:

[0132] Database 1 includes the aircraft maintenance outline database and the flight database. The aircraft maintenance outline database is a digitized storage of the aircraft maintenance outline, including various data used during aircraft maintenance; the flight database stores the aircraft's flight records.

[0133] Aircraft utilization statistics module 2 is used to generate monthly utilization statistics data series, based on aircraft C-check or base-level maintenance intervals. C-check Using formula (1), we obtain the minimum number of consecutive calendar months n that need to be counted, and retrieve the cumulative flight hours n for the current month based on the k-th month from the flight database. fhm,k The monthly utilization rate of the first k months is obtained according to formula (2). The monthly utilization rate of the first n months Arranged in order, the monthly utilization statistics data sequence for the first n months is given as U. (0) ;

[0134] The low utilization prediction module 3 is used to determine whether the maintenance task switching module needs to be activated, and receives U data from the aircraft utilization statistics module. (0) The predicted monthly utilization rate for the (n+1)th month is obtained using the GM(1,1) model function module of the existing grey model. Retrieved from the aircraft maintenance syllabus database fh-low The operation ends if the condition is not met, and if the condition is met, a start signal is sent to the maintenance task conversion module to start the maintenance task conversion module.

[0135] The maintenance task conversion module 4 is used to convert non-calendar day maintenance tasks into calendar day maintenance tasks with low utilization rates. It includes a filtering module 41, a weighting module 42, and a conversion module 43, specifically:

[0136] After receiving the start signal from the low utilization prediction module, the maintenance task conversion module first uses the filtering module 41 to filter maintenance tasks R from the aircraft maintenance outline database whose maintenance interval unit is not based on calendar days. h ;

[0137] Weight module 42 calculates the maintenance task R according to formula (14). h The importance factor s, if s≥8, is important for maintenance task R. h No operation is performed; if s < 8, then maintenance task R is performed. h Send to the conversion module; use the weighting module to send all maintenance tasks R with s < 8. h Send to the conversion module;

[0138] The conversion module 43 converts the maintenance task interval under normal utilization rate into the maintenance task interval under low utilization rate. First, it receives U from the aircraft utilization rate statistics module. (0) Receive the monthly utilization rate for month n+1 from the low utilization prediction module. The average monthly utilization rate u is obtained using formula (15), and the maintenance task R is obtained from the aircraft maintenance outline database. hThe maintenance interval value I0 is obtained from equation (16), and the maintenance interval value I1 under low utilization is obtained from the maintenance task R. h The maintenance interval unit is directly changed to months (MO). It checks whether all maintenance tasks with importance factor s < 8 have completed the conversion; if not, it continues the conversion; otherwise, it sends the conversion results of all maintenance tasks to the maintenance task output module.

[0139] Maintenance task output module 5 is used to receive the conversion result of maintenance tasks from the maintenance task conversion module and output it as the converted maintenance task R. h The numerical value of the maintenance interval and the unit of maintenance interval are I1 and month (MO), respectively.

[0140] Furthermore, the maintenance task conversion module can also send maintenance tasks with s≥8 to the maintenance task output module, and directly display "Reliability-centered maintenance analysis needs to be carried out" after the maintenance task name with s≥8.

[0141] To better understand this invention, the following example of a GVI (General Visual Inspection) maintenance task for an electrical product will be used to specifically illustrate a method for switching maintenance intervals when an aircraft has low utilization. This method includes the following steps:

[0142] S1 obtains aircraft maintenance outline database

[0143] In the aircraft maintenance program database, a certain electrical product is classified as "Electrical" and its failure impact is "Obvious Task-Related". This electrical product includes multiple maintenance tasks, one of which is "GVI" (General Visual Inspection). The maintenance interval for this maintenance task is "600" and the unit of maintenance interval is "flight hours". This means that under normal utilization, the general visual inspection (GVI) maintenance task for this electrical product is performed once every 600 flight hours.

[0144] S2. Determine the number of months requiring statistics and conduct aircraft utilization rate statistics:

[0145] The interval between C tests is 12 months, i.e., I C-check =12, therefore the minimum number of consecutive calendar months to be counted is 11;

[0146] Based on the cumulative monthly flight hours and calendar days for the first 11 months, the monthly utilization statistics sequence U for the first 11 months was obtained. (0) The unit is flight hours per month, specifically...

[0147] U (0) =[80.3 66.3 50.5 62.2 70.7 33.6 20.2 44.5 52.1 19.6 33.2]

[0148] Among them, U (0) This is a series of monthly utilization statistics for the first 11 months.

[0149] S3, Prediction of Low Aircraft Utilization:

[0150] The monthly utilization statistics sequence U for the first 11 months (0) The GM(1,1) model input into the grey model predicts the utilization rate for December. The flight hours per month are 26.8.

[0151] Based on the normal utilization rate of 1500-2800 flight hours / year in the aircraft maintenance program database for this type of aircraft, the lower limit of the average 12-month utilization rate under normal utilization is 125 flight hours / month.

[0152] The forecast indicates that the utilization rate in December will be lower than the lower limit of the average 12-month utilization rate under normal utilization conditions, therefore a change in maintenance tasks is required.

[0153] S4, Maintenance Task Interval Switching:

[0154] S41 uses a conditional filtering method to select maintenance tasks R whose maintenance interval unit is not based on calendar days from the maintenance outline database. h h = 1, 2, ..., N, where N is the number of maintenance tasks with a maintenance interval unit other than calendar days. Since the maintenance interval unit for a certain electrical product's GVI maintenance task is "flight hours", the GVI maintenance task for a certain electrical product is one of the N maintenance tasks selected.

[0155] S42. Determine maintenance task R h The importance of this, and the specific steps are as follows:

[0156] The value of the failure impact factor s1 is determined based on the failure impact of the repair object. The failure impact of a certain electrical product is "obvious task-related", therefore s1 = 2.

[0157] The value of the type factor s2 is determined based on the type of the product being repaired. For a certain type of electrical product, the type is "electrical", therefore s2 = 2.

[0158] The value of the task type factor s3 is determined based on the maintenance task type of the maintenance object. Since the maintenance task type is "GVI", s3 = 3.

[0159] Calculate the importance factor s of the maintenance task.

[0160] s = s1 + s2 + s3 = 2 + 2 + 3 = 7 (14)

[0161] Determine the importance factor s. Since s < 8, execute step S43 to convert the maintenance interval value and time unit for the maintenance task.

[0162] Based on the monthly utilization statistics series of the previous 11 months, U (0) And the monthly utilization rate for December predicted in step S3 The average monthly utilization rate for 12 months is obtained using formula (15). It is 46.7 flight hours per month.

[0163] The maintenance interval value for maintenance tasks obtained from the aircraft maintenance program database is 600. According to equation (16), the maintenance interval value under low utilization is I1 = 600 / 46.7 = 12.8.

[0164] The maintenance interval unit for maintenance tasks will be changed to a month (MO).

[0165] It was found that the maintenance interval for a general visual inspection (GVI) repair task of a certain electrical product is 12.8 MO.

[0166] S5: Compile new maintenance tasks

[0167] The results of step S42, which involve converting maintenance task intervals, are summarized to form new maintenance requirements, which are then marked as applicable to low utilization rates.

[0168] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for switching maintenance intervals when an aircraft is under low utilization, characterized in that: It includes the following steps: S1, Obtain the aircraft maintenance outline; The aircraft maintenance program database is a data storage method for aircraft maintenance programs. The aircraft maintenance program database includes at least the aircraft normal utilization rate range, all aircraft maintenance tasks, failure impact of maintenance objects, maintenance object types, maintenance task types of maintenance objects, maintenance interval values ​​for maintenance tasks, and maintenance interval units for maintenance tasks. S2. Determine the number of months requiring statistics and conduct aircraft utilization rate statistics: Based on aircraft C-check or base-level maintenance intervals (I) C-check The minimum number of consecutive calendar months that need to be counted is: n=[I C-check -1] (1) Among them, I C-check This represents the number of C-checks or base-level maintenance intervals for aircraft, in months; n is the minimum number of consecutive calendar months to be counted. Based on the number of calendar days n of the previous k-th month. day，k And the cumulative flight hours n in the current month fhm，k The monthly utilization rate for the first k months, expressed in flight hours, was obtained. for: Where, n fhm，k Let k be the cumulative flight hours for the first k months, where k = 1, 2, ..., n; S3, Prediction of Low Aircraft Utilization: Based on the monthly utilization statistics of the previous n months, the GM(1,1) model of the grey model is used to predict the monthly utilization rate for the (n+1)th month. if The following conditions must be met Then, the maintenance task is switched, and step S4 is executed, where u fh-low This is the lower limit of the annual utilization rate; S4, Maintenance Task Interval Switching: S41 uses a selection criteria from the maintenance program database to identify maintenance tasks R whose maintenance interval units are engine replacement hours, APU hours, flight hours, and flight cycles. h h = 1, 2, ..., N, where N is the number of maintenance tasks obtained through screening; S42, Determine maintenance task R h The importance of this, and the specific steps are as follows: Calculate the importance factor s of the maintenance task. s = s1 + s2 + s3 (14) Wherein, s1 is the failure impact factor, s2 is the type factor, s3 is the task type factor, and s is the importance factor; Determine the importance factor s. If s ≥ 8, then the importance of maintenance task R is high. h Conduct a reliability-centered maintenance analysis. If s < 8, then execute step S43 for maintenance task R. h Perform the conversion between maintenance interval values ​​and time units; S43. Maintenance task interval conversion calculation: First, the numerical conversion method for maintenance task intervals is as follows: Based on the monthly utilization statistics sequence of the previous n months, U (0) The average monthly utilization rate is obtained by combining the monthly utilization rate predicted in step S3 for month n+1. Obtain maintenance tasks from the aircraft maintenance syllabus. h The maintenance interval value I0 is obtained from equation (16) as follows: The maintenance interval value I1 under low utilization is... Repair task R h The maintenance interval unit is directly changed to a month, resulting in maintenance task R. h The numerical value of the maintenance interval and the unit of the maintenance interval are I1 and month, respectively; Determine whether all maintenance tasks that need to be converted have been converted. If yes, proceed to step S5; otherwise, return to step S42 and continue to convert the next maintenance task. S5: Compile new maintenance tasks The results of step S42, which involve converting maintenance task intervals, are summarized to form new maintenance requirements, which are then marked as applicable to low utilization rates.

2. The method for switching maintenance intervals when an aircraft has low utilization as described in claim 1, characterized in that: In the aircraft maintenance outline in S1 The failure factors affecting the maintenance object are classified into five categories: obvious safety, obvious task-related, obvious economic, hidden safety, and hidden non-safety. The maintenance object type factor is divided into three categories: mechanical, electrical, and electronic. The maintenance task type factors for maintenance objects are divided into seven categories, specifically: SV / LU, VC / OP, GVI, DET, SDI, FNC, and RS / DI; The maintenance interval units used for maintenance tasks include: engine replacement hours, APU hours, flight hours, flight cycles, and calendar days.

3. The method for switching maintenance intervals when an aircraft has low utilization, as described in claim 1, is characterized in that: In step S3, based on the monthly utilization rate statistics of the previous n months, the GM(1,1) model of the grey model is used to predict the monthly utilization rate of the (n+1)th month, specifically as follows: The monthly utilization rate statistics sequence for month n is U (0) , means as follows: Among them, U (0) Let be the statistical data sequence of monthly utilization rates for the previous n months, where each element is the monthly utilization rate obtained according to formula (2). After one accumulation, we get U. (1) in, The summation value; Establish the whitening differential equation Where a is the development coefficient, b is the gray action quantity, and the corresponding gray differential equation is... in Calculate the parameter vector using the least squares method (a,b) T =(B T B) -1 BY (9) in The predicted value of the (n+1)th accumulated value Restore the forecast value for month n+1. Obtain the predicted monthly utilization rate for the (n+1)th month.

4. The method for switching maintenance intervals when an aircraft has low utilization as described in claim 1, characterized in that: The specific values ​​of failure impact factor s1, type factor s24, and task type factor s3 in S42 are as follows: The value of the failure impact factor s1 is determined based on the failure impact of the maintenance object. Specifically, when the failure impact is "obvious safety", s1 = 3; when the failure impact is "obvious task-related" or "hidden non-safety", s1 = 2; when the failure impact is "obvious economic", s1 = 1; and when the failure impact is "hidden safety", s1 = 4. The value of the type factor s2 is determined based on the type of the object being repaired: s2 = 3 when the type is "mechanical"; s2 = 2 when the type is "electrical"; and s2 = 1 when the type is "electronic". The value of the task type factor s3 is determined based on the maintenance task type of the maintenance object, specifically as follows: s3 = 1 when the maintenance task type is "SV / LU"; s3 = 2 when the maintenance task type is "VC / OP"; s3 = 3 when the maintenance task type is "GVI"; s3 = 4 when the maintenance task type is "DET"; s3 = 5 when the maintenance task type is "SDI"; s3 = 6 when the maintenance task type is "FNC"; and s3 = 7 when the maintenance task type is "RS / DI".

5. An aircraft low-utilization maintenance interval conversion device, comprising a database, an aircraft utilization statistics module, a low-utilization prediction module, a maintenance task conversion module, and a maintenance task output module, specifically: The database includes an aircraft maintenance program database and a flight database; the aircraft maintenance program database is a digitized storage of aircraft maintenance programs; the flight database stores the aircraft's flight records. The aircraft utilization statistics module is used to generate monthly utilization statistics data sequences, based on aircraft C-check or base-level maintenance intervals. C-check Using formula (1), we obtain the minimum number of consecutive calendar months n that need to be counted, and retrieve the cumulative flight hours n for the current month based on the k-th month from the flight database. fhm，k The monthly utilization rate of the first k months is obtained according to formula (2). The monthly utilization rate of the first n months Arranged in order, the monthly utilization statistics data sequence for the first n months is given as U. (0) ,in, Formula (1) is: n=[I C-check -1] (1) Among them, I C-check This represents the number of C-checks or base-level maintenance intervals for aircraft, in months; n is the minimum number of consecutive calendar months to be counted. Formula (2) is: Where, n fhm，k Let k be the cumulative flight hours for the first k months, where k = 1, 2, ..., n; The low utilization prediction module is used to determine whether the maintenance task switching module needs to be activated, and receives U data from the aircraft utilization statistics module. (0) The predicted monthly utilization rate for the (n+1)th month is obtained using the GM(1,1) model function module of the grey model. Retrieved from the aircraft maintenance syllabus database fh-low The operation ends if the condition is not met using formula (13), and if the condition is met, a start signal is sent to the maintenance task conversion module to start the maintenance task conversion module. Formula (13) is as follows: The maintenance task conversion module is used to convert maintenance tasks with maintenance intervals measured in engine replacement hours, APU hours, flight hours, or flight cycles into calendar-day maintenance tasks with low utilization rates. It includes a filtering module, a weighting module, and a conversion module, specifically: After receiving the start signal from the low utilization prediction module, the maintenance task conversion module first uses the filtering module to select maintenance tasks R from the aircraft maintenance outline database whose maintenance interval units are engine replacement hours, APU hours, flight hours, and flight cycles. h ; The weighting module calculates the maintenance task R according to formula (14). h The importance factor s, if s≥8, is important for maintenance task R. h No operation is performed; if s < 8, then maintenance task R is performed. h Send to the conversion module; use the weighting module to send all maintenance tasks R with s < 8. h Send to the conversion module; where formula (14) is: s = s1 + s2 + s3 (14) Wherein, s1 is the failure impact factor, s2 is the type factor, s3 is the task type factor, and s is the importance factor; The conversion module converts maintenance task intervals under normal utilization into maintenance task intervals under low utilization. It first receives data from the aircraft utilization statistics module. (0) Receive the monthly utilization rate for month n+1 from the low utilization prediction module. The average monthly utilization rate is obtained using formula (15). Retrieve maintenance tasks R from the aircraft maintenance syllabus database h The maintenance interval value I0 is obtained from equation (16), and the maintenance interval value I1 under low utilization is obtained from the maintenance task R. h The maintenance interval unit is directly changed to a month; it is determined whether all maintenance tasks with importance factor s < 8 have been converted. If not, the conversion continues. If yes, the conversion results of all maintenance tasks are sent to the maintenance task output module. Formula (15) is: Formula (16) is: The maintenance task output module is used to receive the conversion results of maintenance tasks from the maintenance task conversion module and output them. The converted maintenance task R h The numerical value of the maintenance interval and the unit of the maintenance interval are I1 and month, respectively.

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