1、.= NIL-P-81655 66 7799906 019351L T I F-o6-/3 MIL-P-81655 (AS) 3 December 1970 MILITARY SPECIFICATION PITOT STATIC TUBE, L-SHAPED, COMPENSATED, ELECTRICALLY HEATED, GENERAL SPECIFICATION FOR This specification has been approved by the Naval Air Systems Command, Department of the Navy. 1. SCOPE / i S
2、cope - This specification covers the general requirements - 1.1 for aerodynamically compensated, Lshaped, pitot static tubes. 2. APPLICABIE DOCUMENTS L 2.1 General - The following documents of the issue in effect on the date of invitation for bids or request for proposal, form a part of this specifi
3、- cation to the extent specified herein. SPECIFICATIONS Military MIL-P-116 MIL-D-lOOO/l MI L-E -5400 MIL-F-5509 - MILC-5541 MIL-C -5778 MIL-S -7742 Preservation, Methods of Drawings, Engineering and Associated Data Electronic Equipment, Aircraft, General Specification for Fittings, Flared Tube, Flui
4、d Connection Chemical Films and Chemical Film Materials for Covers, Aircraft Components Aluminum and Aluminum Alloys Screw Threads, Standard, Optimum Selected Series: General Specification for Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-P-8Ib
5、55 66 M 777770b 0143512 I M MIL-P-816SS(AS) S PE C IF IC A TION S Military (Continued) MIL-A-8625 MIL -N -1 8 307 STANDARDS Military MIL-STD-143 MIL-STD-46 1 MIL-STD- 704 MIL-STD- 781 MIL-STD-785 MIL-STD-794 MIL-STD-81 O MIL- STD- 1247 MS 33586 MS 33656 Anodic Coating, for Aluminum and Aluminum Allo
6、ys Nomenclature and Nameplates for Aeronautical Electronic and Associated Equipment Specifications and Standards, Order of Precedence or the Selection of Electromagnetic Interference Characteristics Requirements for Equipment Electric Power, Aircraft, Characteristics and Utilization of Reliability T
7、ests, Exponential Distribution Requirements for Reliability Program (for Systems and Equipments) Parts and Equipment, Procedures for Packaging and Packing of Environmental Test Methods Identification of Pipe, Hose, and Tube Lines for Aircraft, Missiles, and Space Systems Metals, Definition of Dissim
8、ilar Fitting End, Standard Dimensions for Flared Tube Connection and Gasket Seal Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL -P -816H AS) 2.2 Availability of Documents - When requesting any of the applicable documents, refer to both title and
9、 number. Copies of this specification and appi- cable documents may be obtained upon application to the Commanding Offlcer, Naval Publications and Forms Center, 5801 Tabor Avenue, Philadelphia, Pennsylvania 19120. 3. REQUIREMENTS 3.1 Detail Specifications - The individual item requirements shall be
10、as specified herein and in accordance with the applicable slash sheet detail specifications. 3.2 Qualification - The Pitot-static tubes furnished under this specification shall be products which have been tested and meet the quality assurance provisions specified herein and have been listed on or ap
11、proved for listing on the applicable qualified products list at the time set for opening of bids. 3.3 Selection of Government Documents - Specifications and standards for necessary commodities and services not specified herein shall be selected according to MIL-STD-143, except as provided in 3.3.1 a
12、nd 3.3.2. 3.3.1 Commercial Parts - Commercial parts having suitable properties may be used where, on the date of invitation for bids, there are no suitable standard parts. in any case, commercial utility parts, such as screws, bolts, nuts, cotter pins, having suitable properties may .be used provide
13、d: a. They can be replaced by the standard parts (MS or AN) without alteration. b. The corresponding standard part numbers are referenced in the parts list and, if practicable, on the contractors drawings. 3.3.2 Standard Parts - With the exception of 3.3.1, MS and AN standard parts shall be used whe
14、re they suit the purpose. They shall be identified on the drawings by their part numbers. 3.4 Materials - Materials that are not specifically designated herein shall be of the best commercial quality, of the lightest practicable weight, and suitable for the purpose intended. 3.4.1 Non-magnetic Mater
15、ials - Non-magnetic materials shall be used for all parts of the tube except where magnetic materials are essential. The extent to which magnetic materials are required shall be reported to the procuring activity. * :.?- 3 . . a Provided by IHSNot for ResaleNo reproduction or networking permitted wi
16、thout license from IHS-,-,-MIL-P-81655 bb m 79777Ob 0143514 5 W MIL-P -81655( AS) 3.4.2 Protective Treatment - When materials are used in the construc- tion of the pitot tube that are subject to deterioration when exposed to climatic and environmental conditions likely to occur during service life,
17、they shall be protected against such deterioration in a manner that will in no way prevent com- pliance with the performance requirements of this specification. The use of any protective coating that will crack, chip, or scale with age or extremes of climatic and environmental conditions shall be av
18、oided. 3.4.3 liberate deleterious or corrosive fumes. This shall-include any fungicidal agents that are used. Toxic and Corrosive Fumes - The materials of the tube shall not 3.4.4 Aluminum Alloy Parts - Aluminum alloy parts shall be covered with an anodic film conforming to MILA-8625. Parts which do
19、 not anodize satisfactorily may be coated in accordance with MIGC-5541. 3.4.5 Nonferrous Materials - Nonferrous materials shall be used in all parts of the tube, except where ferrous materials are essential. 3.4.6 Fungus Resistance - Materials that are nutrients for fungi shal not be used where it i
20、s practicable to avoid them. Where used and not hermet- ically sealed, they shall be treated with a fungicidal agent acceptable to the pro- curing activity. However, if used in a hermetically sealed enclosure, fungicidal treatment will not be necessary. 3.4.7 Dissimilar Metals - Dissimilar metals as
21、 defined in MS 33586 shall not be used in intimate contact with each other, unless protection against elec- trolytic corrosion is provided. 3.4.8 Components - The electronic and mechanical components of the tube shall be in accordance with MIL-E-5400. 3.5 Design and Construction - The design of the
22、tube shall be such that the tube wilI sense pitot and static pressures within the accuracies specified in the detail specification. Fixed aerodynamic compensation shall be achieved by pro- viding an appropriate contour on the nose or by a method whereby the accuracy required in the detail specificat
23、ion will be achieved over the specified speed range without the use of a Mach switch. The static pressure position error (in the region where the tube will be installed) is shown in the detail specification. The supplier shall investigate the effects of angle of attack and sideslip on the sensed pre
24、ssures at this location. Based upon these considerations, a suitable compen- sating contour and suitable location of static ports shall be determined. The tuPi shall be installed on the aircraft as shown in the detail specification. When two 4 Provided by IHSNot for ResaleNo reproduction or networki
25、ng permitted without license from IHS-,-,- MIL-P-1655 66 W 7777906 OLLi3515 7 W MIL-P-81655( AS) tubes are utilized, provisions shall be made to prevent misinstallation of right and left hand units if they are not interchangeable. The tube dimensions shall conform to the detail specification and sha
26、ll be so constructed as to withstand the strains, jars, vibrations, and other conditions incident to shipping, storage, installation and service. 3.5.1 Electrical Connector - The electrical connector shall be as specified in the detail specification. 3.5.2 Heater - The tube shall have one heater whi
27、ch shall be located in the head of the tube and in the strut, Power distribution through the heater during the deicing operation shall conform to the minimum wattage densities specified in the detail specification. The total overload wattage at any time shall not exceed 1, 325w. Heater elements shal
28、l be placed as near as practicable to the heated surfaces. The heater shall be regulated automatically in such a manner that the power dissipated through the heater will be an inverse function of the heater ele- ment temperature. in still air at an ambient temperature between 20“ and 30“ C, the heat
29、er output shall not exceed one half the stabilized deicing power after 5 minutes of heater operation. 3.5.3 Pressure Lines - The pitot pressure exit line shall consist of 1/4 inch outside diameter tubing having a wall thickness of O, 022 inch. The line fitting shall conform to MIL-F-5509 and MS33656
30、-4. The static pressure line shall consist of tubing no smaller than 1/4 inch outside diameter having a wall thickness of O. 022 inch. The static pressure line fitting shall conform to MIL-F-5509 and MS33656-5 or MS33656-6, as applicable. The minimum area of the pitot and static internal pressure li
31、nes shall be not less than that of equivalent 1/4 inch tubing. 3.5.4 Pitot Pressure Chamber - A pitot chamber shall be provided, the volume of which shall not exceed 4 cubic inches. The pressure lines shall be so connected to the plenum chamber that no moisture can enter the Unes. 3.5.5 Static Press
32、ure Chamber - The cross section of the static pres- sure chamber shall be not less than the cross section of 1/4 inch outer diameter tubing (0.022 inch wall thickness) over the entire length of the static pressure chamber. 3.5.6 Concentricity - The cylindrical portion of the tube body shall be conce
33、ntric and uniform within O. O01 inch. There shall be no surface irregularities forward of, or within 1 inch aft of, the static pressure orifices. 3.5.7 Drainage - The tube shall be so designed that water cannot directly enter the pressure line under any service condition, One or two drain holes 5 Pr
34、ovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-shall be provided in the pitot pressure chamber to clear any moisture that may collect. Drain holes shall be O. 029 : inch in diameter. The drain holes shall be located in a heated area. 3.5.8 to MIL-S-77
35、42. Screw Threads - The threads of all machine screws shall conform 3.5.9 Weight - The weight of the tube, including the electrical connector and mounting screws, shall not exceed that specified in the detail specification. 3.5.10 Finishes - Finishes and protective coatings that will crack, chip or
36、scale during normal life or due to extremes of atmospheric conditions shall not be used. The outside of the tube shall have a durable dull finish acceptable to the procuring activity. The cylindrical portion of the tube shall have a machined surface of 32 microinches or better. 3.5.11 Protective Cov
37、ers - The pitot and static pressure openings shall be protected by a full length cover, The pitot and static pressure line coupling threads shall be protected by slip-on covers of nonstrategic material. The design of all protective covers shall conform to MIL-C-5778 and shall be subject to the appro
38、val of the procuring activity. 3.5.12 Interchangeability and Replaceability - All tubes furnished under this specification having the same manufacturers part number shall be functionally and dimensionally interchangeable. Maximum commonality between airplane parts shall be a design objective. If par
39、ts are not common on each model, positive indexing shall be utilized to prevent incorrect installation. Changes in manufacturers part numbers shall be governed by the drawing number requirements of MIL-D-1000/1. be so designed that it will not be a source of electromagnetic interference. The require
40、ments of MIESTD-461 shall govern. 3.5.13 Electromagnetic Interference - The heating element of the tube shall 3.6 Performance - When installed at the location specified in the detail specification, the tube shall sense pitot and static pressures. When installed on the aircraft, the static pressure s
41、ensed by the tube shall be such that the residual. errors will not exceed the limits as specified in the detail specification. The tube shall perform as specified when subjected to the enronmental conditions specified herein. 6 I Provided by IHSNot for ResaleNo reproduction or networking permitted w
42、ithout license from IHS-,-,- - MIL-P-Lb55 bb 9777906 0243537 O 3.6.1 Primary Performance Characteristics - The tube shall be capable of meeting the following primary performance characteristics: a. Nominal aircraft static pressure altitude error requirement - When the tube is installed on the aircra
43、ft at the specified location, the nominal or mean residual pressure error at a particular Mach number shall not exceed the values shown in Table I at any altitude or aircraft weight except between Mach O. 95 and 1.05. TABLE I Flight Mach No. o. 20 0.30 0.40 O. 50 O. 60 0.70 O. 80 0.90 o. 95 1.05 1.1
44、0 1.20 1.40 1.60 1.80 2.00 A H (Feet) 20 40 60 100 140 200 270 360 450 750 750 750 750 750 1000 1 O00 b. Variation allowance for nominal or mean residual pressure error - The combined error effect of reproducibility, installation, aircraft weight, altitude, aircraft configuration, and flight Mach nu
45、mber in level flight shall be within the tolerances specified in Table II. TABLE II Flight Condition - Allowable* Tolerance, Ft Power Approach i20 Maximum Endurance Cruise i50 Maximum Range Cruise 150 Maximum Mach Number Obtainable Basic Engine (Continuous Power Operation) *50 Military Power Operati
46、on Il00 * Allowable tolerance may be defined as the variation around a nominal or mean. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. - . - . . . - . MIL-P-Lb55 66 799790b 0343538 2 W MIL -P -816SS(AS) c. Static pressure reproducibility require
47、ment between Pitot-static tubes - The static pressure reproducibility of I25 feet at maximum range cruising altitude and Mach number shdl be substantiated by aerodynamic testing of each Pitot-static tube. The test method with substantiating data shall be submitted to the procuring activity for appro
48、val. d. Pitot and static pressure errors - The tube shall sense pitot and static pressures within the tolerance specified in the detail specification. e. Deicing and anti-icing - The tube and strut heater shall remove and completely clear accumulated ice from heated areas when subjected to the envir
49、onmental conditions specified in the detail specification. 3.6.2 Secondary Performance Characteristics - The tube shali be cap- able of meeting the following secondary performance characteristics: a. Rated voltage - Operation from single phase power, 115V 400Hz, category “B“ of MIL-STD-704. Normal voltage fluctuation shall have no effect on the unit. b. Insulation - Voltage potential of 550 VAC 400 Hz between electrical co
