1、MIL-DTL-25949F = 9999906 L999328 7T9 9 INCH-POUND i MIL-DTL-25949F I MAY 1995 SUPERSEDING 25 APRIL 1978 MIL-A-25949E DETAIL SPECIFICATION ACCELEROMETER, AIRCRAFT RANGE -5 TO IOG UNITS, INTEGRALLY LIGHTED This specification is approved for use by all Departments and Agencies of the Department of Defe
2、nse. I. SCOPE 1.1 Scope. This specification covers integrally lighted -5 to + 1 Og range, aircraft accelerometers. I .2 Classification. Accelerometers covered by this specification shall be of the following types, as specified (see 6.2): ABU-4AIA - Nonhermetically sealed ABU-4BA - Hermetically seale
3、d 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are needed to meet the requirements specified in sections 3, 4, and 5 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or
4、as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cited in sections 3,4, and 5 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specificati
5、ons. standards. and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standard
6、s (DODISS) and supplement thereto, cited in the solicitation (see 6.2). SPECIFICATIONS DEPARTMENT OF DEFENSE MIL-P-I 16 Preservation, Methods Of Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: O
7、klahoma City Air Logistics CenterITICLA, 3001 Staff Drive, Tinker AFB OK 73145-5990 by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. AMSC NIA FSC 66 1 O DISTRIBUTION STATEMENT A. Approved for public release; distribution is
8、 unlimited. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-DTL-25949F 9999906 1999329 b35 MIL-C-5541 MI L-L-6085 MIL-S-7742 MI L-A-8625 MIL-C- I4806 MIL-L-25467 MI L-L-27 1 60 MIL-G-8 1704 MIL-C-83488 STAN DARDS FEDERAL FED-STD-595 MILITARY MIL
9、-STD- I O0 MIL-STD- 129 MIL-STD- 130 MI L-STD-454 MI L-STD-785 MIL-STD-810 MI L-STD-889 MS23009 MS28 105 MS33558 MS33585 MI L-DTL-25949F Chemical Conversion Coatings On Aluminum And Aluminum Alloys Lubricating Oil, Instrument, Aircraft, Low Volatility Screw Threads, Standard, Optimum Selected Series
10、: General Specification For Anodic Coatings, For Aluminum And Aluminum Alloys Coating, Reflection Reducing, For Instrument Cover Glasses And Lighting Lighting, Integral, Red, Aircraft Instrument, General Specification For Lighting, Instrument, Integral, White, General Specification For Glass, Aircra
11、ft Instrument, Lighting Wedge And Cover Coating, Aluminum, Ion Vapor Deposited Wedges Color Engineering Drawing Practices Marking For Shipment And Storage Identification Marking Of US Military Property Standard General Requirements For Electronic Equipment Reliability Program For Systems And Equipme
12、nt Development And Production Environmental Test Methods And Engineering Guidelines Dissimilar Metals Accelerometer-Aircraft, Integrally Lighted, ABU-4AA And ABU-4BA Cover Glass, Aircraft Instrument Dial Numerals And letters, Aircraft Instrument Dial, Standard Form Of Pointers, Dial, Standard Design
13、 Of Aircraft Instruments HANDBOOK MIL-HDBK-78 I Reliability Test methods, Plans And Environments For Engineering Development, Qualification And Production (Unless otherwise indicated, copies of the above specifications, standards and handbooks are available from the Standardization Document Order De
14、sk, 700 Robbins Ave, Building 4D, Iliiladelphia, PA 191 I 1-5094) 3.22 Other government docunient. drawines. and publications. The following other Governinent documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues are
15、 those cited in the solicitation. Air Force Drawing 834656 I (A copy of the Air Force drawing is available from OC-ALUTILDO, Tinker AFB OK 73 145-5990. 2.3 Order of precedence: In the event of a conflict between the text of this document and the references cited herein (except for related MS standar
16、ds), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-DTL-2
17、5949F = 999990b I1999330 357 W MIL-DTL-25949F 3.1 MS sheets. The individual item requirements shall be as specified herein and in accordance with the applicable MS sheet. In the event of any conflict between the requirements ofthis specification and the MS sheet, the latter shall govern. 3.3 First a
18、rticle. When specified (see 6.2). a sample shall be subjected to first article inspection (see 6.3) in accordance with 4.4. 3.3 Materials 3.3.1 Metals. Metals shall be of the corrosion-resistant type or treated to resist corrosion due to fuels, salt fog, or atmospheric conditions likely to occur in
19、storage or normal service. 3.3. I. I Dissimilar metals. Unless suitably protected against electrolytic corrosion, dissimilar metals shall not be used in intimate contact with each other. Dissimilar metals are defined in MIL-STD-889. 3 3.3 Nonniametic niaterials. Noniiiagnetic materials shall be used
20、, except where magnetic materials are essent ia I. 3.3.3 Lubricants. When required, the lubricant used shall be in accordance with MIL-L-6085. The amount of lubricant used shall be sufficient for at least 1,000 hours of operation. 3.3.4 Protective treatnient. When materials are used in the construct
21、ion of tlie accelerometer that are subject to deterioration when exposed to climatic and environmental conditions likely to occur during service usage, they shall be protected against such deterioration in a manner that will iii no way prevent compliance with the performance requirements ofthis spec
22、ificatioii. Tlie use of any protective coating that will crack, chip, or scale with age or extrenie of climatic and environmental conditions shall be avoided. 3.4. Desicn and construction 3.4.1 Design. The accelerometer shall be designed to indicate aircraft accelerations in maneuvers and rough air.
23、 and shall conform to MSi3009 aiid FIGURE 1. 3.4.2 ResDoiise. Tlie accelerometer shall be designed to comply with the response characteristics specified in 4.5.4. 3.4.3 Construction. Tlie construction shall be reasonably simple to permit overhaul or repair with the use of tools aiid fixtures normall
24、y available commercially. The acceleronieter shall be so constructed as to withstand the nornial strains. jars. vibrations, and such other conditions as are incident to shipping, storage, installation, and service without failure. 3.4.4 Pivots. bearings and -ears. Pivots, bearings, and gears shall o
25、perate smoothly and shall be as near frictionless as practical. 3.4.5 Case. The case shall conform to MS23009. Tlie Bezel and that part ofthe case visible from the cockpit side of the instrument panel shall be finished iii lusterless black, color No. 37038 of FED-STD-595. The reiiiaiiider oftlie cas
26、e iiiay be finislied in black aiid shall be adequately protected to satisfactorily withstand the environmental test coiiditions specified Iiereiii. 3.4.5.1 Hermetic sealing ABU-4BA). The case shall be hermetically sealed and shall be so designed that the internal mechanism may be reiiioved, replaced
27、, and tlie case resealed without the use of special tools and fixtures unless they are approved by the procuring activity. Hermetic sealing shall be such that the sealing will not be affected by the action of any atmosphere to which the indicator iiiay be subjected. The case shall meet the necessary
28、 pressure requirements when tested 10r leaks by means ofa iiiass spectrometer-type ofheliuiii leak detector. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L-DTL-25949F 3.4.5.2 Filling medium ABU-4B/A). The filling medium shall be of at least 9
29、8 percent purity, free of dust particles, and shall contain not more than 0.006 milligram of water vapor per liter (dewpoint -65C) at the filling pressure. The filling medium shall be a mixture of 88 to 92 percent nitrogen and the remainder helium. The absolute pressure of the filling medium in the
30、case shall be 12 to 14.7 psi. 3.4.5.3 Filling medium tube. The filling medium tube for the hermetically sealed unit shall be located on the rear of the case and shall not interfere with the locking knob operation or the electrical connection. 3.4.6 Cover glass. The cover glass shall conform to MS28
31、105 and MIL-G-8 1704. 3.4.6.1 Reflection-reducing coatinz. All cover glass and lighting wedges shall be provided with a reflection reducing coating that meets the requirements of MIL-C- 14806. This requirement can be accomplished by obtaining a certificate of compliance from the manufacturer of the
32、anti-reflective coating that states the coating meets the requirements of MIL-C-14806. 3.4.7 Dial. The dial shall conform to FIGURE 1 and shall be fastened securely to the case or upon the frame of the mechanism by not less than two screws in such manner that it will not loosen or turn when the acce
33、lerometer is vibrated. 3.4.7.1 Distance from dial to cover glass. The distance between dial and cover glass shall be not greater than 0.250 inch. 3.4.8 Pointers. The accelerometer shall have three pointers; one main pointer for indicating instantaneous acceleration, and two auxiliary pointers, one f
34、or indicating maximum positive acceleration, and one for indicating maximum negative acceleration. The pointers shall conform to FIGURE 1. They shall be light and sufficiently rigid to prevent oscillation under vibration. They shall be firmly attached to the mechanism, yet shall be readily adjustabl
35、e. 3.4.9 Ratchet mechanism. Each auxiliary pointer shall be provided with a ratchet device, in order that indication of the maximum plus and minus deflections of the main pointer will be maintained until the auxiliary pointers are reset to obtain a new reading. 3.4.9.1 Auxiliary pointer return mecha
36、nism. A mechanism shall be provided for resetting the auxiliary pointers into juxtaposition with the main pointer. A knob, located as shown on MS23009, shall be provided for operating the return mechanism. The shaft of this knob shall be capable of withstanding a load of 15 I 1 pound applied perpend
37、icular to the shaft at the extreme outward end of the knob without permanent deformation. Stops shall be provided in order that the auxiliary pointers, when reset, shall not indicate a lower or higher reading than that indicated by the main pointer. Stops shall be a part of the mechanism connecting
38、the pointers and shall not directly engage them. Operation of the return mechanism shall require 3 to 8 pounds of force on the knob. 3.4.9.2 Main pointer mechanism. The main power mechanism shall not engage the mechanism of the auxiliary pointers when the imposed acceleration is less than the accele
39、ration indicated by the auxiliary pointers. 3.4.1 O Stoiis for acceleration-responsible element. Mechanical stops shall be provided for arresting the motion of the acceleration-responsive element and the pointers when the accelerometer is subjected to accelerations beyond the limits specified. One s
40、top shall engage the element at an acceleration of not less than -5.1 g and not more than - 5Sg, and the other at an acceleration of not less than +lO.lg and not more than +10.5g. 3.4.1 1 LockinP device. A device for manually locking the position of the acceleration-responsive element shall be provi
41、ded in order to protect the mechanism of the accelerometer from possible damage during shipment. The device shall be controlled by means of a suitable knurled knob, located at the rear of the case and marked as shown on MS23009. The force required to lock and unlock the unit shall be 4.5* 1 pound. 4
42、 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-25949F W 9999906 1997332 12T W MI L-DTL-25949F 3.4.12 Adiustment. The mechanism shall be provided with means to adjust or correct the indications. This means of adjustment shall be reasonably s
43、imple to manipulate and of a type that adjustment can be accomplished with tools ordinarily possessed by an instrument repairman. 3.4.13 Indication and range. The accelerometer shall indicate vertical accelerations when the plane of the mounting lugs is vertical and the +5.0 graduation is at top cen
44、ter. When in this position, norinal gravity shall be indicated at +I g. The accelerometer shall be designed to indicate accelerations in the range -5 to + I Og. 3.4.14 Integral lightinq. The indicator shall incorporate two separate parallel integral lighting circuits. The red lighting shall be in ac
45、cordance with MIL-L-25467 and the white lighting shall be in accordance with MIL-L-27 160. In the event of conflict between this specification and either MIL-L-25467 or MIL-L-17160, this specification shall govern. Lighting shall operate on 5V ac or dc. Lighting acceptability of production indicator
46、s shall be based on visual comparison with a prime standard. The method of lighting shall be approved by the procuring activity prior to fabrication. 3.4.14.1 Prime standard. The prime standard lighting reference instrument shall be prepared as follows: A minimum of 20 areas covering the entire face
47、 of the indicator shall be measured in foot-lamberts for brightness. A minimum of IO areas covering the entire face of the indicator shall be measured for color. The prime standard instrument and its recorded coverall brightness and color measurements shall be approved by the procuring activity. The
48、 standard shall be checked at least every 50 hours of operation or 120 days, whichever occurs first, to determine any change in brightness or color. Variations greater than *20 percent in two or more areas shall require return of the standard for corrective action. The data and, if required by the p
49、rocuring activity, the prime standard shall be submitted for evaluation and reapproval or corrective action, or both. 3.4. I5 Reliability 3.4.15.1 Reliabilitv program. The contractor shall establish a reliability program in accordance with MIL- STD-785, task I O I. 3.4.15.2 Reliability in mean time between failure MTBFI. The acceleronieter shall have a minimum of 1,000 hours of mean (operating) time between failures when tested and accepted as outlined under the requireiiients 014.6. 3.4.1 5.3
