1、IMIL-A-8867C(AS)10 June 1987SUPERSEDINGMIL-A-8867(ASG)18 May 1960?41LITARYSPECIFICATIONAIRPLANE STRENGTH AND RIGIDITYGROUND TESTSThis specification is approved for use within the NavalAir Systems Command, Department of the Navy, and isavailable for use by all Departments and Agencies of theDepartmen
2、t of Defense.1. SCOPE1.1 Scope. Thlsspecificationcontains the requirements which, incombinationwith other applicable specifications,define the ground testsrequired for structural evaluation of fixed wng piloted atrplanes. Thetypes of testing include, but are not llmited to:a. Oesign development test
3、s.b. Pre-production component tests.c. Static tests-completeairframe.d. Fatigue tests-completeairframe.e. Qrop tests of structurally complete airframe.f. Cabin pressure tests.9“ Leakage tests of integral fuel tanks.h. Structural dynamic tests.i. Proof tests for flight articles.“Beneficial comments (
4、recommendations,additions, deletions) and any pertinentdata which may be of use in improving this document should be addressed to:Naval Air EngineeringCenter, Systems Engineering and StandardizationDepartment (Code 53), Lakehurst, NJ 08733-5100, by using the self-addressedStandardizationDocument Imp
5、rovement Proposal (DD Form 1426) appearing at theend of this document,or by letter.AMSC N/A FSC 1510DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-886,X(4S),.Ai1
6、.2 Purpose. The purpose of this specification is to define the requirementsfor laboratory structural tests for development and proof-of-designof strengthand rigidity of Navy fixed wing piloted airplanes. a711.3 Modifications and amplifications. This specification will be modifiedand amplified by con
7、tracts, by type and detail specifications, and by design dataspecificationsand addenda thereto.2. APPLICABLE DOCUMENTS2.1 Government documents.2.1.1 Specifications and standards. The following specificationsandstandards form a part of this specification to the extent secified herein.Unless otherwise
8、 specified, the”issues ofin the issue of the Department of Defense(DODISS) and supplement thereto, cited inSPECIFICATIONSMILITARYMIL-L-8552MIL-D-8708these documents shall be those listedIndex of Specifications and Standardsthe solicitation.Landing Gear, Aircraft Shock Absorber (Air and Oil Type).Dem
9、onstration Requirements For Airplanes.MIL-A-8860MIL-A-8863MIL-A-8866MIL-A-8868MIL-A-8870STANDARDSMILITARYAirplane Strength and Rigidity - General Specification for.Airplane Strength and Rigidity - Ground Loads for Navy Procured Aircraft.Airplane Strength and Rigidity - Reliability Requirements,Repea
10、ted Loads, Fatigue and Damage Tolerance.Airplane Strength and Rigidity - Data and Reports.Airplane Strength and Rigidity - Vibration, Flutter, andDivergence.MIL-STD-2066 Catapulting and Arresting Gear Forcing Functions forAircraft Structural Design.(Copiesof specificationsand standards required by c
11、ontractors in connectionwith specific acquisition functions should be obtained from the contractingactivity or as directed by the contracting activity.)2Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.MIL-A-$867C(AS)e 2.1.2 Order of precedence. IrIt
12、he event of a conflict between the text ofthis soeclflcaton and the references cited herein (excet for associated detailspecifications, specification sheets, or MS standards), the text of this specifi-cation shall take precedence. Nothing in this specification,however, shallsupersede applicable laws
13、 and regulations unless a specific exemption has beenobtained.3. REQUIREMENTS3.1 General. The contractor shall furnish test specimens for performance of tests specified herein as modified and ampllfied by the contract or supportingcontractual documentation. Repairs or replacementof parts shall be ma
14、de to testspecimens as necessary to permit performanceof tests to the specified loadsherein. These repairs or replacements shall be representativeof those Installedin the flight test articles and fleet airplanes unless, for the convenience ofthe Government, the Government spec4flcallydecides otherwi
15、se. Such repairs orreplacements shall be demonstrated by test or analysls as specified by theGovernment to comply with contract test objectives.3.1.1 Terminology Definitions and symbols are in accordance with 6.5through 6.5.1S herein: MIL-A-8860, and MIL-A-8870.3.1.2 Location of tests. The contract
16、will specify whether the tests are tobe performed by the Government or by the contractor at his plant.3-1.3 Test witnesses. Before performing a required test, the contractingactivity representative shall be notified in sufficient time so that he maywitness the test and certify results and observatio
17、ns contained in the testreport. When the contracting activity representative Is notified, he shall beinformed if the test is such that interpretationof the behavior of the structureunder load is likely to require engineeringknowledge and experience so that hemay provide a qualified engineer to witne
18、ss the test and certify the observationsand results recorded during the test.3.1.4 Tests performed by the Government. In the event structural tests areperformed by the Government, the contractor shall provide test personnel to actin an advisory capacfty in connection with the planning and execution
19、of thetests. The advisory personnel shall be familiar with the stress analysis of thetest structure. All loads and analysis data and drawings that will be requiredby the Government in the planning and performanceof the tests are specified inMIL-A-8868. The responsibility for stopping any tests upon
20、indicationsof pre-mature failure and for making necessary structural alterations or reinforce-ments to preclude premature failure shall rest with the contracting activity.The contractor shall be responsible for services and material necessary toincorporatechanges In the test article to preclude prem
21、ature failure, and forrepairs after fail-ingload tests.3.2 I)esigndevelopment and pre-productiontests. For the initial phase ofthe required structural verification program, the contractor shall conduct designdevelopment and pre-production component tests as defined herein.Provided by IHSNot for Resa
22、leNo reproduction or networking permitted without license from IHS-,-,-.,MIL-A-8867C(AS)3.2.1 Design development tests. These tests are to establish design con-cepts, and to provide design information and early design validation. Designdevelopment, static and fatigue tests include but are not limite
23、dto:a. Element tests for:(1) Materials selection including crack propagation, fracturemechanics, and structural allowable.(2) Fatigue spectrum variation effects.(3) Process evaluation, including assessment of finish.(4) Fastener and bonding evaluation., (5) Manufacturing methods evaluation.b. Struct
24、ural configuration development”tests for:(1) Splices and joints(2) Panels (basic sect(3) Panels with cutout(4) Fittings.(5) Critical stucturalon).areas which are difficult to analyze dueto complexity of design.3.2.1.1 Design development tests composites. These tests are used toestablish design allow
25、able, verify analysis, and evaluate design details.Additionally, the design development tests are a part of the overall structuralcertification procedure in that the test results are used in the interpretationof the full-scale airframe static and fatigue test results. Design developmenttests range n
26、 complexity from coupon tests that are used to evaluate materialand fastener behavior to full-scale components such as wing torque box structureand landing gear backup structure. Both static and fatigue tests are required inthe design development test program. The actual number and types of tests re
27、-quired will depend upon the aircraft design. A design development test planshall be prepared by the contractor and shall require approval by the procuringactivity.3.2.1.2 Design development testing approach for composites. A building blockapproach to design development testing is essential for comp
28、osite structures,because of the mechanical properties variability exhibited by composite materials,the inherent sensitivityof composite structures to out-of-plane loads and theirmultiplicityof potential failure modes. The essence of the building blockapproach for composites is as follows:Provided by
29、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I .blIL-A-8867C(AS)ea. Perform design a?purpose of designowables testing using coupon type test specimens. Theallowable testing is to establish strength and lifearameters for structural design. In planning a desig
30、n allowable testprogram, it Is Important that ;ufficleit numbers of tests be conducted togenerate meaningful statistical parameters. In general the number ofspecimens requfred depends on the scatter of the data. The higher thedata scatter, the greater the number of specimens required. The designallo
31、wable tests should be planned to develop the strength to temperature/moisture envelope relationship for the full range of the service tempera-ture of the airplane. Tests should provide design allowable for eachfailure mode anticipated.b. Use the designlanalyslsof the airplane structure to select cri
32、tical areasfor test verification. Determine the most strength-criticalfailure modefor each area selected, and establish the test environment which willproduce this failure mode. Special attention should be given to matrixsensitive failure modes such as compression and bondline and potentialstress “h
33、ot spots” caused by out-of-plane Ioading. The sensitivityofcomposite matrix dominated failure modes to the temperature/moistureenvironment makes environmental test simulation a key Issue in a designdevelopment program. The approach for static testing should be that thetest environment used in the on
34、e that produces the failure mode whichgives the lowest strength. That 1s, the worse case environment, or thetemperature associated with the most critical load should be used. Theenvironmental complexity necessary for fatigue design development testingwI1l depend on the projected load-temperatureprof
35、iles in service and themoisture content as a functfon of the airplane usage and compositelaminate thfckness.c. Design and test a series of specimens representing these areas, each oneto slmu?ate a single failure mode. These initial specimens wll generallybe low complexity specimens. From this point
36、a series of specimens shouldbe designed and tested which simulate progressive design complexity. Pre-mature failure or an unanticipated failure mode are indicationsof flawsin the design and/or analysis and corrective action must be taken beforeproceeding to the next level of complexity. If mixed fai
37、lure modes areobserved In a certain specimen type, more tests are required to determinethe most critical failure mode and the associated mean strength/life. Thebuilding block approach Is shown In Figure 1 which depicts a typicaldesign development program for a wing structure.3.2.2 i%e-production com
38、ponent design verification tests. These tests are toallow early verification of the static and fatigue strength capability of finalor near-final structural designs of critical structural areas. The pre-produc-tion component test program shall be proposed by the contractor and conducted asapproved by
39、 the contracting activity. These tests shall include but not belimited to:a. Splices and joints.b. Fittings.5Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.I$IL-A-8867C(AS)IBLJILIMNG BLOCK APPROACHFigure 1. Building block approach.6Provided by IHSN
40、ot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-8867C(AS).*1Q1)!Ii0c. Panels.d. Assembles, Including 3.2.2a, b, and c, above.e. Full-scale components such as wing carry-through, horizontal tailsupport, wing pivots, landlng gear and support, composites, etc.3.3
41、 Full-scale tests. The contractor shall perform tests in accordance withthe requirements soeclffed herein, as mdified and amplfied by the contract orsupporlng contracual documents, unless the contractspecifie that tests willbe performed by the Government. Three full-scale laboratory test articles sh
42、allbe used: one for the static tests; one for the fatigue tests; and one for thedrop tests. In addltlon, an empennage test article shall be used for dynamicfatigue test of 3.9.2.3.3.1 Sequence of tests. The required structural tests of thissoeciflcation shall be performed In such sequence and tmelin
43、ess, that tests totfieminimum loads and sinking speeds requrd prior to release for fltght otherthan normal flyng, release for demonstration, delivery of vehicles forprellmlmary evaluation and trials, and servfce use shall be completed at least30 days prior to the scheduled date for such release or d
44、elivery. In particular,the structural tests shall be so sequenced that the flght loads survey anddemonstration program will not be delayed. Test sequencing shall be such as tominimize the possibility of failures that would resu?t in damage and subsequentrepairs that ould significantlydelay completio
45、n or Influence the validity ofother requlrecistructural tests. All tests to design ultimate load and designsinking speeds shall be completed prior to performing failing load tests for anycondttion. In addition, loads for the failing load test shall reflect the datafrom the flight load surveys of PiI
46、L-D-8708,as applicable. In all cases, thetest sequencing shall be approved by the Government prior to starting the testprogram. The following conditions shall also apply:a. Repeated load tests of integral fuel tank structureson the testarticle shall be completed pror to performing tests for any othe
47、rconditions to loads which oulciresult in permanent deformationof theairframe structure.b. Design ultimate load tests for flight conditions shall be completedprior to performing tests for other than flight conditions to designultimate loads or to maximum design loads.c. Should the test program be de
48、layed such that fleet operations arescheduled before critical testing can be accomplished, the contractorshall revise the sequence of testing as directed by the Navy to ensurethat critical testing is accomplished tn a timely manner.3.3.2 Strenqth-test structures.a. Items such as fixed equipment and
49、useful load and their support struc-tures may be omitted from the test structure provided the omission ofthese parts does not significantlyaffect the load, stress, thermaldistributions, or deflection of the structure to be tested, and provid-ed the omitted parts would not be critically ?oaded in the tests ifthey were Installed. All equipment, bracket, etc. attachment holesmust be included.7Provided by IHSNot for ResaleNo reproduction or ne
