1、. I INCH-POUNDI MIL-A-27670D(USAF) 15 DECEMBER 1994 SUPERSEDING 16 AUGUST 1965 MIL-A-27670C(USAF) MILITARY SPECIFICATION AMPLIFIER-INDICATOR GROUP INDICATED AIRSPEED NA24G- 1 O This specification is approved for use by the Department of the AU Force and is available for use by all Departments and Ag
2、encies of the Department of Defense. 1. SCOPE i. i Senge. This specification covers the requirements for one type of aircraft indicated airspeed amplifier- indicator group, designated NA4G- I O. 2. APPLICABLE DOCUMENTS 2.1 Government documents. 2.1.1 s- ms ificati k . The following specifications, s
3、tandards, 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 Standards (DODISS) and supplement thereto, cited in the solicitation (
4、see 6.2). SPECIFICATIONS FEDERAL PPP-B-636 Box, Shipping, Fiberboard Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Oklahoma City Air Logistics CenterTICLA, 3001 Staff Drive, Tinker AFB OK 7314
5、5-5990 by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. AMSC NfA FSC 6610 -. D Approved for public release; distribution is unlimited. Provided by IHSNot for ResaleNo reproduction or networking permitted without license fro
6、m IHS-,-,-MIL-A-27b70D ? 9999906 1995128 MIL-A-27670DQJSAF) MILITARY MIL-P- 1 16 MIL-C-675 MIL-C-50 15 MIL-E-5400 MIL-S-7742 MIL-M-779316 MIL-A-8625 MIL-T-25627 MIL-L-27 160 MIL-B-27497 MIL-C-38037 MIL-C-83488 STANDARDS FEDERAL FED-STD-595 MILITARY MIL-STD- 100 MIL-STD- 129 MIL-STD-130 MIL-STD-461 M
7、IL-STD-462 MIL-STD-470 MIL-STD-47 1 MIL-STD-704 MIL-STD-78 1 MIL-STD-8 10 MIL-STD-889 MIL-STD-970 MIL-STD-2073-1 MS3 3 5 5 8 278 Preservation, Methods Of Coating Of Glass Optical Elements (Anti-Reflection) COMCOS, Electrical, “AN“ Type Electronic Equipment, Aircrafl, General Specification For Screw
8、Threads, Standard, Optimum Selected Series, General Specification For Meter, Time Totalizing, Miniature, Digital, 115 Volts, 400 HZ Anodic Coatings, For Aluminum And Alumhum Alloys Transmitter, Synchro, Angle Of Attack Or Side Slip Lighting, Insirument, Integral, White, General Specification For Bea
9、ring, Jewel, Sapphire Or Ruby Synthetic Computer, Central AU Data CPU-43/A Coating, Aluminum, ION Vapor Deposited Colors Engineering Drawing hctices Marking For Shipment And Storage Identification Marking Of U.S. Military Property Requirements For The Control Of Electromagnetic Interference Emission
10、s And Susceptibility Measurement Of Electromagnetic Interference Characteristics Maintainability Program Requirements (For Systems And Equipments) Maintainability Demonstration Aircraft Electric Power, Characteristics Reliability Testing For Engheerhg Development Environmental Test Methods Dissimila
11、r Metals Standard manufactured by any prior alternate source d. Transmitter, Synchro, Angle of Attack or Side Slip in accordance with MIL-T-25627. 3.5.7 Jewel be-. Jewel bearings shall be in accordance with MIL-B-27497. 3.6 Performance. The amplifier-indicator group shall be capable of meeting the r
12、equirements specified herein when subjected to the following conditions: a. Temperature - Temperatures ranging from -55“ to +71 C. b. Scale error - Scale errors and tolerances specified in tables I, II, III, and IV. c. Insulation leakage - Withstand a potential of 250V dc applied between any electri
13、cal pin contact and any d. Vibration. metal part of the indicator case. (I) In accordance with Method 514.2 of MIL-STD-810. (2) In accordance with Method 5 14.2 of MIL-STD-810. e. Temperature-altitude - Amplifier operation in accordance with figure 5. f. Slew speed - Slew speed tolerances as specifi
14、ed in table III. g. Altitude - Pressures ranging from 3 1 .O to 2.1 18 inches Hg. h. Acceleration - In accordance with Method 513.2 of MIL-STD-810. i. Shock - In accordance with Method 516.2 of MIL-STD-810. j. Humidity - Relative humidity up to 100 percent. k. Fungus - Exposure to simulated fungus g
15、rowth as encountered in desert areas. 1. Salt fog - Exposure to simulated salt sea atmosphere. m. Sand (fine dust) - Exposure to sand (fine dust) particles as encountered in desert areas. n. Dielectric strength - Subjection to 250V 60 cps for five seconds. 3.6.1 -t. The amplifier-indicator group sha
16、ll not cause a free magnet to deflect more than 5“ when the unit is held in various positions on an east-west line with its nearest part 12 inches from the center of the magnet in a magnetic field with a horizontal intensity of O. 18 *0.01 oersted. 3.6.2 Electro magnetic - interference. The amplifie
17、r-indicator shall meet the electromagnetic interference requirements of MIL-STD-461 as follows: CE102 CSIOI REO 1 RS i 03 CSl14 CS115 CS116 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-27670D 9999906 1995132 7T9 3.6.3 Insulation breakdown
18、. The amplifier shall withstand application of 500V for 5 seconds under the conditions specified in 4.6.10. The current leakage shall be not more than 4.5 ma. 3.7 Inter- . All parts having the same manufacturers part number shall be functionally and dimensionally interchangeable. The item identifica
19、tion and part number requirements of MIL-STD- 100 shall govern the manufacnirers part numbers and changes thereto. 3.8 Operation. 3.8.1 Aircraft mach na . The aircraft mach number moving scale shall be actuated by a servo mechanism with dual speed transmitting synchro input. The input to the instrum
20、ent control transformer synchro shall be linearly proportional to mach number over the range of 0.2 to 1 .O. The tape scale factor shall be 1.350 inches per O. 1 mach number. 3.8.1.1 Jv acht The servo-drive mechanism shall be so designed as to accurately position the moving scale at the center refer
21、ence line. Provision shall be made to prevent the moving scale fkom being driven beyond specified limits. #en the input signal is below 0.2 mach, the movable scale shall remain fued at 0.2 mach. Electrical zero of the follow-up servo-synchro shall be at mach 0.2. Electrical scale factor shall be 1,0
22、00“ per unit mach for the fuie sycnhro and 200 per unit mach for the coarse synchro. Servo slew speed shall be at least seven mach per minute. 3.8.2 Command mach nu mk. The command mach number symbol and associated numerical counter shall be actuated by the slew switch located below the mach tape. 3
23、.8.2.1 Comma nd mach number mec hanization. The mechanism shall be designed to accurately position the command mach index at the appropriate position, with respect to the aircraft mach number moving scale, and this position shall also be displayed on the command mach counter. When the commanded mach
24、 number is beyond the visible range of the instrument dial, provision shall be made to disengage the drive mechanism; the index shall assume a position at the scale extremity and remain visible in the area marked B on figure 1. When the command index is positioned to any value on the aircraft mach n
25、umber moving scale, there shall be no apparent relative motion between command index and moving scale resulting from servoed motion of the moving tape in either direction. Motion of either servoed element shall not result in interaction with the other. The reading of the command mach marker against
26、the mach tape (when the command value is within the visible range of the mach scale) shall, at all times, read within 0.005 mach of the command value as read on the counter. When the switch is released, the servo shall provide suitable braking action to prevent coasting of the-command this position
27、shall also be displayed on the command airspeed counter. When the command airspeed is beyond the visible range on the instrument dial, provision shall be made to disengage the drive mechanism and the index shall assume a position at the scale extremity and remain visible in the area marked B on figu
28、re 1. A center-lock position shall be provided on the command airspeed slewing switch which will position and retain the index on the center-reading reference line. In this position, the counter shall continuously provide numerical indication of indicated airspeed. The reading of the command airspee
29、d marker against the airspeed tape (when the command value is within the visible range of the airspeed scale) shall, at all times, read within three knots of the command value as read on the counter. The servo shall provide suitable braking action to prevent coasting of the command index upon releas
30、e of the switch. 3.8.2.5 Safe speed. The safe-speed moving scale shall be actuated by a servo mechanism with synchro input. The input to the indicator synchro control transformer shall represent a transmitting synchro angle range of +9“ to - 86“. Scale factor shall be 2.7“ per 0.3 12 inch of tape. 3
31、.8.2.5.1 Mechanization. Mechanization shall be as specified in 3.8.1.1 except that the servo mechanism shall position the moving scale in response to the angle of attack input from a remote computer. Electrical zero shall be at O“ angle of attack. Electrical zero of the indicator followup synchro sh
32、all position the tape display to the midpoint of the stall warning band. 3.8.2.5.2 Damping. A damping adjustment shall be provided, accessible externally on the amplifier, for the purpose of adjusting to optimum damping characteristics. 3.8.2.6 Counters. The command airspeed and mach counters shall
33、be of the continuous-rotation type for the counter wheel displaying only the least significant digit. Counter wheels that operate intermittently shall not be used. 3.8.2.7 Slewing switches. Manually operated slewing switches as shown on figure 1 shall be provided to operate the command symbols and a
34、ssociated counters. The switch shall be spring centered. The slewing speed imparted to the command symbol shall be proportional to the amount the switch is displaced from center within the minimum and maximum speeds specified. The up position of the switch shall drive the command symbol and correspo
35、nding counter dispIay toward increasing value of the function. The slew switch shall incorporate a detent that will permit indexing of one unit on the associated counters. The slew switch dimensions shall be in accordance with figure 15. 3.8.2.8 Elaosed time indicator. A 10,000-hour four digit type
36、elapsed time indicator conforming to MIL-M- 7793/6 shall be provided and so mounted in each indicator that the dial is visible on the side or rear of the case. 3.8.2.9 necornmession. The indicator shall be so designed as to withstand explosive decompression of the surrounding atmosphere. Operation s
37、hall not be affected when a pressure difference of 16 inches of mercury is applied instantaneously between the interior and exterior of the case. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-m1L-A-27670D 999990b 3995334 573 MIL-A-27670DwSAF) 3.8
38、.2.10 Self-test circuit. A self-test circuit shall be provided in the indicator so that the mach and airspeed tapes may be positioned at a present value. 3.8.2.11 JM -. 1 Monitor circuits shall be provided that will detect malfunctions in the airspeed and mach components and in the intercabling, inc
39、luding the transmitting synchro within the air data system. Malfunction shall cause the IAS and mach warning flags to appear. A calibrated series voltage (stick-off) shall be included in the monitor circuits to provide self-test capability. This series voltage, which is equivalent to the maximum tri
40、p level, for airspeed only, shall cause the warning fiag to appear when the excitation voltage is removed from the air data transmitter. 3.8.2.12 13 failures will constitute rejection. Failure to reach an accept decision in accordance with the criteria specified shall stop all deliveries until an ac
41、cept decision is reached. Pattern failures, as defmed in MIL-STD-781, shall require corrective action for all equipment produced to date and produced subsequently regardless of an accept or reject decision. Reporting shall be in accordance with MIL-STD- 781. 25 Provided by IHSNot for ResaleNo reprod
42、uction or networking permitted without license from IHS-,-,- MIL-A-27b70D 999990b L995L52 597 = MIL-A-27670DQJSAF) 4.6.42.2 hoduction. The four systems specified in 4.5.2.5 shall be subjected to a production reliability test in accordance with MIL-STD-781, test plan I, except as modified herein, whi
43、ch shall demonsate a contractual MTBF of 600 hours. Each of the four indicators and amplifiers shall be tested a minimum of 900 hours of actual electrical operation. The cycling time of five to six minutes per cycle for each indicator function display, with a minimum of 13,200 cycles per function, s
44、hall include monitor test, self test, and operation of all slew switches. A cycle shall consist of the excursion from the function minimum value to maximum and return to minimum. The test shall begin when rated power is applied to the system. After four hours of rated power on, the power shall be tu
45、rned off for a period of two hours. This procedure of power-one, power-off shall be repeated until the test is completed. Only the power-on portion of the test shall be used in calculating the total test time required by test plan 1. The system shall be tested at room temperature for approximately 6
46、4 percent of the test time, at -10C for approximately 14 percent of the test time, and at + 50C for approximately 22 percent of the test time shown in table VI. During the fifth cycle, the indicator shall be vibrated in accordance with Method 514.2, procedure 1, part 1 (curve c), category b.1 equipm
47、ent of MIL-SD-810, except as folIows: Cycling time shall be the time of one sweep time. A range for curve c of 5 to 50 Hz and an accelemtion level of + lg from 23 to 50 Hz. Also, only the sinusoidal cycling portion will be required. The transition from the fourth to the fifth cycling period shall be
48、 completed in the shortest possible time to allow the vibration test to be conducted during the temperature change from -10C to + 25C. After each cycle period of electrical operation shown in table VI, the system shall be subjected to a scale error test of at least three stations per function. Any m
49、alfunction, including failure to meet the scale error test, shall be recorded, the test interrupted while repairs are made, and the test then continued hm the point of interruption. Upon completion of the reliability test, the system shall again be tested for scale error with a 50 percent increase in tolerances. Failure to meet the increased-tolerances scale error test shall be considered a malfunction. This test may be interrupted for normal weekend shutdown. If a reject decision is reached
