1、SOCIETV OF AUTOMOTIVE ENOINEERS. ,a. AS 441 486 LEXINGTON AVENUE A E R 0 S P A C E S TA N D A R D NEW YORK 17. N.Y. BANK AND PITCH INSTRUMENTS Issusd -20-61 (Indicating Stabilized TypexGyroscopic Horizon, Attitude GyroXTurbine-Powered Subsonic Aircraft) Rsvissd 1. PURPOSE: This Aerospace Standard es
2、tablishes the essential minimum safe performance standards for gyroscopically stabilized Bank and Pitch Indicating Instruments primarily for use with turbine-power subsonic transport aircraft, the operation of which may subject the instruments to the environmental conditions specified in Paragraph 3
3、. 3. 2. SCOPE: This Aerospace Standard covers both direct and remote display instruments. 3. GENERAL REQUIREMENTS: 3. 1 Material and Workmanship: 3.1. 1 Materials: Materials shall be of a quality which experience and/or tests have demon- str.ated to be suitable and dependable for use in aircraft ins
4、truments. 3. 1. 2 Workmanship: Workmanship shall be consistent with high-grade aircraft instrument manufacturing practice. 3. 2 Identification: The following information shall legibly and permanently be marked on the instrument or na,meplate attached thereto: (a) Name of instrument (b) SAE AS 441 (c
5、) Manufacturers part number (d) Manufacturers serial number or date of manufacture (e) Ma.nufacturers na,me and/or trademark (f) Rating (electrical, vacuum, etc.) (g) Explosion (Category) 3.3 Environmental Conditions: The following conditions have been established as minimum design requirements. Tes
6、ts shall be conducted as specified in Sections 5, 6, and 7. 3.3. 1 Temperature: When installed in accordance with the instrument manufacturers in- structions, the instruments shall function over the range of ambient temperatures as listed in Column A below and shall not be adversely affected by expo
7、sure to the tem- perature shown in Column B below. Instrument Location: A B Pressurized Areas -30 to +70 C -65 to +70 C Non-Pressurized or Externa,l Areas -55 to +70 C -65 to +70 C Copyrlht 1964 Mr Socleb of NuYomotive Ensinsrs, Ina Printd In U. t. A. A s 441 Iasued -20(7 BANK AND PITCH INSTRUMENTS
8、_ Reviaed -2- l 3. 3. 2 Altitude: When installed in accordance with the instrument manufacturers instruc- tions, the instruments shall function from sea level up to the altitudes and tempera- tures listed below. Altitude pressures are per NACA Report 1235. The instrument shall not be adversely affec
9、ted following exposure to extremes in ambient pressure of 50 and 3 inches Hg absolute respectively. Instrument Location Alt. Ft. Temp. C Pressurized Areas 15,000 50 Non-Pressurized or Externa.l Areas 60,000 40 3. 3. 3 Vibration: When installed in accorda.nce with the instrument manufacturers instruc
10、- tions, the instrument shall funetion and shall not be adversely affected when subjected to vibrations of the following characteristics. Maximum Double Maximum Frequency Amplitude Acceleration Instrument Location (cps) (inches) () Nacelle, Nacelle Mounts, Wings, 5-1000 0.036 10 Empennage and Wheel
11、Wells Fuselage Forward of Spar Area 5-500 0.036 2 Center of Spar Area 5-1000 0.036 4 Aft of Spar Area 5-500 0.036 7 500-1000 - 5 Vibration Isolated Rack 5-1000 0.030 1 Instrument Panel 5-30 0.020 - 30-1000 - 0.25 3. 3. 4 Humidity: The instrument shall funetion and shall not be adversely affected fol
12、lowing exposure to any relative humidity in the range from 0 to 95% at a temperature of ap- proximately 70 C. 3.4 Explosion Cateory: The instrument component, when intended for installation either in the uninhabited areas of non-pressurized aircraft or in the non-pressurized areas of pressurized air
13、craft, shall not cause an explosion when operated in an explosive atmos- phere. The component shall meet the requirements applicable to the explosion category below. Specifically, any instrument component which can be an ignition source and is intended for installation in an area in which combustibl
14、e fluid or vapor may result from abnormal conditions, e. g., fuel line leakage, shall meet the requirements of Category I. If the intended location is an area where combustible fluid or vapor can occur during normal operation, e. g. fuel tank, the instrument component shall meet the requirements of
15、Category II, listed below: F1 , . i U BANK AND PITCH INSTRUMENTS I Issued 1-6l1 As 441 1 Revised -3- Cateory Definition Requirements I Explosion Proofed; case not designed to prevent flame or explosion propagation. II Explosion Proofed; case de- signed to prevent flame or explosion propagation. III
16、Hermetically Sealed IV Instrument not capable of causing an explosion Test per Para. 7. 4. 1. 1 Test per Para. 7. 4. 1. 2 Test per Para. 7. 7 Shall not be capable of producing a spark with more than 1. 0 milli- joules of energy and shall not have a short circuit current of more than 100 milliamperes
17、 J 3. 5 Fire Hazard: The instrument shall be so designed to safeguard against hazards to the aircraft in the event of malfunction or failure, and the maximum operating temperature of surfaces of any instrument component contacted by combustible fuel or vapor shall not exceed 20 C due to self-heating
18、. 3. 6 Radio Interference: The instruments shall not be the source of objectionable interfer- ence, under operating conditions at any frequencies used on aircraft, either by radia- tion or feedback, in electronic equipment installed in the sa.xne aircraft as the instru- ment. 3.7 Manetic Effect: The
19、 magnetic effect of the instruments shall not adversely affect the performance of other instruments installed in the same aircraft. 3. 8 De-Compression: When installed in accordance with the instrument manufacturers in- structions the instrument shall function and not be adversely affected following
20、 exposure to a pressure decrease from 22 to 2 inches Hg in 2 seconds. 4. DETAIL REQUIREMENTS: 4. 1 Display Markins: 4. 1. 1 Finish: Unless otherwise specified by the user, matte white material shall be applied to all graduations, numerals, and indication means. , Non-functional surfaces and markings
21、 shall be durable dull black. 4. 1. 2 Graduations: The graduations shall be arranged to provide the maximum of read- ability consistent with the accuracy of the instrument. AS 441 Iasued .-20-61 BANK AND PITCH INSTRUMENTS Reviaed -4- “ 1 4. 1. 3 Numerals: The display shall include sufficient numeral
22、s to permit quick and posi- tive identification of each graduation. Numerals shall distinctly indicate the gradua- tion to which each applies. 4. 1.4 Instrument Title: The instrument title shall be of the same approximate size but no larger than the numerals. The title may be of the same finish as t
23、he numerals. The units of ineasure shall appear on the dial in lettering noticeably smaller than either the numerals or title. 4. 1. 5 Visibility: The indicating means and all markings shall be visible from any point within the frustum of a cone the side of which makes an angle of at least 30 degree
24、s with the perpendicular to the dial and the small diameter of which is the aperture of the instrument case. The distance between the dial and the cover glass shall be a practical minimum. 4. 2 Power Variation: The instrument shall properly function with +15%o variation in d-c voltage and/or +10% va
25、riation in a-c voltage and +5% variation in frequency. 4. 3 Power Malfunction Indication: Means shall be incorporated in the instrument to indi- cate when adequate power (voltage and/or current) is not being made available to all phases required for the proper operation of the instrument. The indica
26、ting means shall indicate a failure or a malfunction in a positive manner. 4. 4 Herrnetic Sealing: When hermetically sealed, the case shall be filled with an inert gas, free of dust particles, and sufficiently dry so that fogging of the indicator glass does not occur during the low temperature tests
27、 of this Aerospace Standard. 4. 5 Synchro Requirements: The synchro requirements shall be in accordance with the conditions specified in ARP 461A. 4. 6 Gyro Caing: If a gyro caging means is provided, it shall not be capable of locking the gyro in a caged position. Any failure which causes the gyro t
28、o be caged shall be indicated in a positive manner. 4. 7 Operating Range: The instrument shall be operable following maneuvers of 360 de- grees in bank and 360 degrees in pitch. Controlled precession may be employed to achieve the 360 degrees in pitch. 4. 8 Methods of Display: The method of displayi
29、ng bank and pitch attitude is specified below: Bank attitude shall be pictorially displayed so that the true relationship between air- craft bank attitude and the actual earths horizon is clearly presented over the range of indication. Pitch attitude shall be pictorially displayed so that a change b
30、etween the aircrafts pitch attitude and the actual earths horizon is clearly presented in the proper rela- tionship over the range of indication. wJ - BANK AND PITCH INSTRUMENTS lasued I-2-J AS 441 Revised -5- 4.9 Indicating R.equirements: 4. 9. 1 Indicating Range: The range of indication in pitch s
31、hall be at least +25 degrees. The range of indication in bank shall be at least +100 degrees. 4. 9. 2 Indicating Graduations: Right and left bank gradua.tions shall at least be provided at 30 degrees. 4. 9. 3 Pitch Attitude Reference: A zero pitch reference shall be provided. An adjustable pitch ref
32、erence marker or indicator may be provided to accommodate a range of pitch attitude trim. 4. 9. 4 Turn Error: The bank or pitch indicating error resulting from a coordina.ted turn of 180 degrees in one (1) minute at a true airspeed of 180 knots shall not exceed 3 de- grees. 4. 9. 5 Take-off Accelera
33、tion Error: This error shall be kept to a minimum. 5. TEST CONDITIONS: 5. 1 Atmospheric Conditions: Unless otherwise specified, all tests required by this Aero- space Standa.rd shall be made at an atmospheric pressure of approximately 29. 92 inches Hg and at an ambient temperature of approximately 2
34、5 C, and at a relative humidity of not greater than 85 percent. When tests are conducted with the atmospheric pressure or temperature substantially different from these values, allowance shall be made for the variation from the specified conditions. 5. 2 Vibration to Minimize Friction: Unless otherw
35、ise specified herein, all tests for per- formance may be conducted with the instrument subjected to a maximum vibration of 0. 001 inch double amplitude at a frequency of 10 to 60 cycles per second. The term double amplitude, as used herein, indicates the total displacemnt from positive maxi- mum to
36、negative maximum. 5. 3 Vibration Equipment: Vibration equipment shall be such as to allow vibration to be ap- plied along each of three mutually perpendicular axes of the instrument at frequencies and amplitudes consistent with the requirements of Paragraph 3. 3. 3. 5.4 Power Conditions: Unless othe
37、rwise specified, all tests shall be conducted at the power rating recommended by the manufacturer. 5. 5 Position: Unless otherwise specified herein all tests shall be conducted with the instru- ment in its normal operating position. 6. INDIVIDUAL PERFORMANCE REQIJIREMENTS: All instruments shall be s
38、ubjected to tests by the instrument manufacturer to demonstrate specific compliance with this Aero- space Standard, including the following requirements where applicable. 6. 1 Dielectric: Each instrument shall be tested by the method of inspection listed in Para- graph s 6. 1. 1 and 6. 1. 2. A S 441
39、 Iasued G-20-61 BANK AND PITCH INSTRUMENTS Rev;sed -6- 6. 1. 1 Insulation Resistance: The insulation resistance measured at 200 volts d-c for five seconds between all electrical circuits connected together and the metallic case shall be not less than 5 megohms. Insulation resistance measurements sha
40、ll not be made to circuits where the potential will appear across elements, such as windings, re- sistors, capacitors, etc., since this measurement is intended only to determine adequacy of insulation. 6.1. 2 Overpotential Tests: The instruments shall not be damaged by the application of a test pote
41、ntial between electrical circuits and between electrical circuits and the metallic case. The test potential shall be a sinusoidal voltage of a commercial fre- quency with an rms value of five times the maximum circuit voltage, or perParagraph 6. 1. 2. 1 or 6. 1. 2. 2, whichever applies. The potentia
42、l shall start from zero and be increased at a uniform rate to its test value. It shall be maintained at this value for five seconds, and then reduced at a uniform rate to zero. Since these tests are intended to insure proper electrical isolation of the circuit com- ponents in question, these tests s
43、hall not be applied to circuits where the potential will appear across elements, such as windings, resistors, capacitors, etc. 6.1. 2. 1 Hermetically sealed instruments shall be tested at five times the maximum circuit voltage up to a maximum test voltage of 200 volts rms. 6. 1. 2. 2 Circuits that o
44、perate at potentials below 15 volts are not to be subjected to over- potential tests. 6. 2 Startin: Instrument performance shall be achieved within 3 minutes after normal rated power is applied. By application of 80 percent of rated voltage, the gyro rotor shall start and continue to rotate. 6. 3 Se
45、ttlin Error: When the gyro has erected and attained equilibrium speed and the indi- cator and/or the gyro component has been oscillated on a roll, pitch and yaw simulator through an angle of + 7-1/2 degrees about each axis at a frequency of 5 to 7 cycles per minute for 30 minutes and then returned t
46、o level position, the alignment of the bank and pitch indicators with their respective zero indices shall be within one degree. 6.4 Verticality: With the instrument mounted on a level platform and the gyro running at equilibrium, an azimuth rotation of the platform of 180 degrees shall result in les
47、s than 1. 0 degree change in either the roll or the pitch indication. The rotation of the platform and the 180 degree instrument reading shall be accomplished within a time period of 10 seconds. If the gyros spin is is inclined, for purposes of turn error correction, there shall be, in addition to t
48、he tolerance, a change in pitch indication equivalent to twice the angle of inclina,tion. 6. 5 Sealin : Hermetically sealed components shall be tested for leaks by means of a mass spectrometer type helium leak detector or equivalent. The leak rate shall not exceed 76 microns per hour per cubic foot
49、of filling gas at a pressure differential of one atmos- phere. NOTE: A micron-per-hour-per-cubic-foot leak rate is defined as that gas leakage which would cha,nge the pressure of one cubic foot volume by the amount of one micron (one-millionth of a meter of inercury) in one hour. 1 !1 a19 _ BANK AND PITCH INSTRUMENTS Issued L-20-6 I/ + Revised 1J -7- 7. QUALIFICATION TESTS: As mariy instruments or components deemed necessary by the manufacturer to demonstrate that all instruments will compl
