1、Comments, suggestions, or questions on this document should be addressed to Defense Logistics Agency Aviation VEB, 8000 Jefferson Davis Highway, Richmond, VA 23297-5616 or e-mailed to STDZNMGTdla.mil. Since contact information can change, you may want to verify the currency of this address informati
2、on using the ASSIST database at https:/assist.daps.dla.mil. AMSC N/A FSC 6610 INCH-POUND MIL-DTL-5421D 5 April 2011 SUPERSEDING MIL-DTL-5421C 13 July 2007 DETAIL SPECIFICATION TUBES, PITOT, ELECTRICALLY HEATED, AIRCRAFT This specification is approved for use by all departments and agencies of the De
3、partment of Defense. 1. SCOPE 1.1 Scope. This specification covers all types of two-wire electrically heated pitot tubes for use with airspeed indicators. 1.2 Classification. The pitot tubes are of the following styles and rated voltages (see 6.2): 1.2.1 Style. The styles of pitot tubes are as follo
4、ws: AN5811 - “L“ shaped, inverted AN5812 - “L“ shaped SAE AS5813 - Straight 1.2.2 Rated voltage. The rated voltage of the pitot tubes are as follows: Type 1 - 24-volt, direct current Type 2 - 115-volt, 400-Hz, single phase, alternating current Inactive for new design after 5 May 1999. Provided by IH
5、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-5421D 2 1.3 Part or identifying number (PIN). The PIN to be used for pitot tubes acquired to this specification is created as follows: 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section
6、 are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cauti
7、oned that they must meet all specified requirements of the documents cited in sections 3 and 4 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this d
8、ocument to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract (see 6.2). DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-S-7742 - Screw Threads, Standard, Optimum Selected Series: General Specification for. MIL-A-8625 - Ano
9、dic Coatings for Aluminum and Aluminum Alloys. AN3115 - Receptacle - Airspeed Tube Electrical. AN5811 - Tube, Pitot, Electrically Heated, “L“ Shaped, Inverted. AN5812 - Tube, Pitot, Electrically Heated, “L“ Shaped. 1 = Type 1 - 24-volt, direct current 2 = Type 2 - 115-volt, 400-Hz, single-phase, alt
10、ernating current AX XXXX - X Specification number (Style): 5811 - “L“ shaped, inverted 5812 - “L“ shaped 5813 - Straight AN or AS prefix Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-5421D 3 DEPARTMENT OF DEFENSE STANDARDS MIL-STD-31000 - T
11、echnical Data Packages. (Copies of these documents are available online at https:/assist.daps.dla.mil or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Non-government publications. The following documents form a part of this document
12、to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract (see 6.2). AEROSPACE INDUSTRIES ASSOCIATION (AIA) NASM35207 - Screw, Machine-Pan Head, Cross Recessed, Carbon Steel, Cadmium Plated, UNF-2A (IN./MM). NASM35338 -
13、Washer, Lock-Spring, Helical, Regular (Medium) Series. (Copies of these documents are available online at http:/www.aia-aerospace.org/ or from Aerospace industries Association, 1000 Wilson Boulevard, Suite 1700, Arlington, VA 22209.) ASTM INTERNATIONAL ASTM B 117 - Standard Practice for Operating Sa
14、lt Spray (Fog) Apparatus. (Copies of these documents are available online at http:/www.astm.org/ or from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959.) SAE INTERNATIONAL SAE AS5813 - Tube - Pitot, Electrically Heated. (Copies of these documents are avail
15、able online at http:/www.sae.org/ or from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001. 2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein (except for related
16、specification sheets), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-54
17、21D 4 3. REQUIREMENTS 3.1 Specification sheets. The individual item requirements shall be as specified herein and in accordance with the applicable specification sheet. In the event of any conflict between the requirements of this specification and the specification sheet, the latter shall govern. 3
18、.2 First article. When specified (see 6.2), a sample shall be subjected to first article inspection in accordance with 4.3. 3.3 Materials. Materials shall be specified herein. Materials that are not specifically designated shall be of the best commercial quality and suitable for the purpose intended
19、. 3.3.1 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable materials should be used to the maximum extent possible provided that the material meets or exceeds the operational and maintenance requirements and promotes economically advantag
20、eous life cycle costs. 3.3.2 Metals. Metals shall be corrosion resistant unless protected to resist corrosion during normal service life. 3.3.3 Nonmagnetic materials. Nonmagnetic materials shall be used for all parts of the tube except where magnetic materials are essential. 3.4 Standard parts. MS o
21、r AN standard parts shall be used wherever they are suitable for the purpose. They shall be identified on the drawing by their parts numbers. Commercial utility parts such as screws, bolts, nuts, and cotter pins may be used provided they possess suitable properties and are replaceable by the MS or A
22、N standard parts without alteration and provided the corresponding standard parts numbers are referenced in the parts list and, if practicable, on the contractors drawings. In the event there is no suitable corresponding standard part in effect on the date of invitation for bids, commercial parts ma
23、y be used provided they conform to all requirements of this specification. 3.5 Design and construction. The design of the tubes shall conform to AN5811, AN5812, and SAE AS5813 as specified. The tubes shall be constructed so that no parts will work loose in service. The tubes shall be built to withst
24、and the normal strains of jars, vibrations, and such other conditions as are incident to shipping, storage, installation, and service without failure. 3.5.1 Finish. Protective coatings and finishes shall not be used that will crack, chip, or scale during normal service life or due to extremes of atm
25、ospheric conditions. 3.5.1.1 Tube exterior. The tube exterior shall be finished with a durable dull color acceptable to the procuring activity. 3.5.1.2 Aluminum-alloy parts. Aluminum-alloy parts shall be covered with an anodic film conforming to MIL-A-8625. Provided by IHSNot for ResaleNo reproducti
26、on or networking permitted without license from IHS-,-,-MIL-DTL-5421D 5 3.5.2 Screw threads. Machine screw threads greater than 0.060 inch in diameter shall be in accordance with MIL-S-7742. 3.5.3 Drainage. The tube shall be designed so that when ice on the tube is melted under flight conditions, th
27、e resulting water shall drain from the tube and not be conducted into the impact pressure line where it may freeze. 3.5.4 Heating element. The tubes shall be electrically heated. The heating element placed in the nose of the tube shall have a minimum rating of 120 watts at the rated voltage with the
28、 outer shell of the tube immersed in a water-ice mixture at a temperature of 0 C (32 F). 3.5.5 Electrical circuit. The electrical circuit of the tube shall be of the two-wire type and shall be provided with an AN3115-1 snap type receptacle. 3.5.6 Sleeve assembly. The sleeve assembly shown on SAE AS5
29、813 drawing shall be furnished as a part of each SAE AS5813 tube. 3.5.7 Shipping caps. The threads of the coupling and the total pressure opening shall be suitably protected by a slip-on cap of non-strategic material. 3.6 Interchangeability. All parts having the same manufacturers part number shall
30、be directly and completely interchangeable with each other with respect to installation and performance. Changes in manufacturers part numbers shall be governed by MIL-STD-31000. 3.7 Performance. The tubes shall satisfy the performance requirements specified in section 4 when subjected to the applic
31、able tests. 3.8 Identification of product. The following information shall be etched, engraved, or stamped on each tube in a location that will not interfere with the proper operation of the tube. Name of tube (as shown on the AN or AS drawing) Rated voltage AN or AS part number National stock numbe
32、r Manufacturers part number Contract or order number Manufacturers name or trademark U.S. Property Word “TOP“ at location specified on the AN or AS drawing 3.9 Installation. 3.9.1 Installation instructions. Unless otherwise specified (see 6.2), the contractor shall furnish one printed copy of instru
33、ctions for each tube. The instructions shall contain illustrations and diagrams if necessary. Prior to printing, two copies shall be furnished to the procuring activity for approval. The instructions shall be arranged on a single sheet of paper either 8-1/2 inches X 11 inches, or 11 inches X 17 inch
34、es. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-5421D 6 3.9.2 Mounting screws. The contractor shall furnish four NASM35207-226 mounting screws and four NASM35338-41 lockwashers for installing the assembly. 3.9.3 Envelope. When required (s
35、ee 6.2), an envelope containing the installation instructions, mounting screws, and lockwashers shall be furnished with each tube. The following information shall be printed on the face of the envelope: IMPORTANT This envelope contains installation instructions and mounting screws. 3.10 Workmanship.
36、 Workmanship shall be in accordance with the best practice for high quality aircraft instruments. 4. VERIFICATION 4.1 Classification of inspections. The inspection requirements specified herein are as follows: a. First article inspection (see 4.3). b. Conformance inspection (see 4.4). 4.2 Inspection
37、 conditions. Unless otherwise specified, all inspections shall be performed in accordance with the test conditions specified in paragraphs 4.2.1 and 4.2.2. 4.2.1 Ambient temperature. The ambient temperature for all tests shall be 20 C to 30 C (68 F to 86 F). 4.2.2 Rated voltage. The rated voltage fo
38、r type 1 tubes shall be 24 volts direct current (VDC) and the voltage for type 2 tubes shall be 115-volt, 400 Hz, single phase alternating current. 4.3 First article inspection. First article inspection shall consist of the individual tests of 4.5 and all the tests of 4.6. 4.3.1 First article sample
39、. The first article sample shall consist of three tubes of each part number specified in the acquisition order. The sample shall be representative of production pitot tubes. The samples shall be identified with the manufacturers part number and any other information specified by the procuring activi
40、ty (see 6.2). 4.4 Conformance inspection. Conformance inspection shall consist of the individual tests of 4.5 and the tests 4.6.1 through 4.6.6. 4.4.1 Conformance inspection sample. Five tubes that have passed the individual tests shall be selected at random from each lot of 500 tubes or less. The f
41、ive selected tubes shall be subjected to the tests of 4.6.1 through 4.6.6. A lot shall consist of all the tubes of the same part number submitted for acceptance under the same acquisition order. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL
42、-5421D 7 4.5 Individual tests. Each tube submitted for acceptance under contract shall be subject to the following tests. In addition, each tube shall be subject to any additional test specified herein which the inspector considers necessary to determine conformance with the requirements of this spe
43、cification. 4.5.1 Examination of product. Each tube shall be examined to determine conformance with the requirements of this specification not covered by applicable tests. 4.5.2 Leakage. The impact pressure opening and drain holes shall be sealed and a test manometer connected to the impact connecti
44、on. A pressure of 14.73 pounds per square inch (psi) (30 inches of mercury) shall be applied. The pressure shall not drop below 14.71 psi (29.95 inches of mercury) after a one-minute period. 4.5.3 Electrical circuit. The rated voltage shall be applied across the terminals of the tube for a period of
45、 two minutes at an ambient temperature of 20 C to 30 C (68 F to 86 F). After the two-minute period the power shall be 80 watts (W) +20/-5 percent. 4.5.4 High potential. The tube shall be subjected to a high potential test with the voltages listed in table I at a commercial frequency applied between
46、each terminal and the case for a period of 60 seconds. No damage to the wiring or insulation shall result from this test. TABLE I. Potential test voltages. Tube type Sea level 50,000 feet (altitude) 1 550 VRMS 110 VRMS 2 1,250 VRMS 500 VRMS 4.6 Tests. 4.6.1 Vibration. The tubes shall be subjected to
47、 vibration such that a point on the tip of the tube will oscillate 1/4 inch. The test shall be conducted for a period of three hours consisting of one-hour periods at 1,000, 2,000, and 3,000 cycles per minute (Hz). Type I tubes shall be operated at 30 VDC and type 2 tubes shall be operated at 120 VA
48、C, 400 Hz, single phase continuously during this test. No leaks or failures of any kind shall result from this test. 4.6.2 Power consumption. Each tube shall be supported vertically and fully immersed in a water-ice mixture at a temperature of approximately 0 C (32 F) within 1/4 inch of the mounting
49、 surface. The tube shall remain in this water-ice mixture for ten minutes. The electrical connector pins shall then be connected through a test circuit containing a 7-ampere fuse for type 1 tubes or a 2-ampere fuse for type 2 tubes to a source of the applicable rated voltage. The initial current surge shall not cause the fuse to fail. After the specified potential has been applied for a period o
