MIL-HDBK-1530B(USAF)
5.4.3 Force structural maintenance documentation. Force structural maintenance documentation should be created to identify inspection and modification requirements and the estimated economic life of the airframe. Complete detailed information (when, where, how, and cost data as appropriate) should be included in the documentation. It is intended that the U.S. Air Force will use this plan to establish budgetary planning, force structure planning, and maintenance planning. To support documentation changes to account for operation beyond the design service goal, repairs, corrosion, or potential of loss of fail-safety from the onset of widespread fatigue damage, the following information should be included:
a. finite element models of the structure
b. loads and spectrum generation database c. materials database
d. crack growth analysis procedures
e. system-peculiar corrosion susceptibility database.
5.4.4 Loads/environment spectra survey. The objective of the loads/environment spectra survey is to obtain time history records of those parameters necessary to define the actual stress spectra for the critical areas of the airframe. It is envisioned that 100-percent of the operational air vehicle will be instrumented to measure such parameters as velocity, accelerations, altitude, fuel usage, temperature, strains, etc. Ten- to twenty-percent of the data will be captured by the U.S. Air Force as part of the force management task as described in 5.5 and should be used to construct the baseline operational spectrum as described in 5.4.4.2. Data acquisition should start with delivery of the first operational air vehicle. The data would also be available to detect when a significant change in usage occurs to require an update in the baseline operational spectra. If the individual air vehicle tracking program as described in 5.4.5 obtains sufficient data to develop the baseline operational spectra and detect significant usage changes, a separate survey program (or continuation thereof) as described herein may not be required.
5.4.4.1 Data processing provisions. Data processing provisions (including reformatting) and computer analysis methods should be compatible with the U.S. Air Force data analysis system. It is envisioned that facilities and personnel, except for reformatting/transcribing and other data processing and analysis functions for which capabilities exist within the U.S. Air Force and are approved for use, will be used to process data collected during a defined period beginning with delivery of the first production air vehicle. Plans for transfer of data processing provisions to U.S. Air Force facilities including training of U.S. Air Force personnel should be determined prior to contract signature.
5.4.4.2 Analysis of data and development of baseline operational spectra. These flight data will be used to assess the applicability of the design and durability test loads/environment spectra and to develop baseline operational spectra. The baseline operational spectra should be used to update the durability and damage tolerance analyses as described in 5.4.1.2 when a statistically-adequate amount of data has been recorded. Subsequent revisions of the baseline operational spectra may be required when mission requirements change.
5.4.5 Individual air vehicle tracking program. The objective of the individual air vehicle tracking program is to predict potential flaw growth in critical areas of each airframe which are key to verification damage growth limits of Sensitivity analysis (4.14) in JSSG-2006, inspection times, and economic repair times, whether driven by usage or environmental exposure. It is envisioned that 100-percent of the fleet will be instrumented with a goal that 100-percent of the data will be captured. In practice, capture of 90- to 95-percent of the data is considered reasonable. Data acquisition should start with delivery of the first operational air vehicle. The program should include serialization of major components (e.g.; wings, horizontal and vertical stabilizers, landing gears, etc.) so component tracking can be implemented by the U.S. Air Force.
5.4.5.1 Tracking analysis method. An individual air vehicle tracking analysis method should be developed to establish and adjust inspection and repair intervals for each critical area of each airframe, based on the individual air vehicle usage data. Damage tolerance and durability analyses and associated test data will be used to establish the analysis method. These analyses will provide the capability to predict crack growth rates, time to reach
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