1、The Engineering Society For Advancing Mobility Land Sea Air and Space I N T E R N A T I O N A L400 Commonwealth Drive, Warrendale, PA 15096-0001AEROSPACESTANDARDCopyright 1988 Society of Automotive Engineers, Inc.All rights reserved.Printed in U.S.ASAE Technical Standards Board Rules provide that: “
2、This report is published by SAE to advance the state of technical andengineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use ,including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE revi
3、ews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invit esyour written comments and suggestions.Submitted for recognition as an American National StandardIssued 3-1-42Revised 11-5-87Superseding AS 28AAS 28BSPARK PLUGS, AIRCRAFT ENGINET
4、HIS REVISION CONTAINS ONLY EDITORIAL CHANGES1. SCOPE : This specification covers reciprocating engine shielded and unshielded spark plugs.2. CLASSIFICATION : Spark plugs covered by this specification shall be of the following type and sizes, as specified:14MM1/2” Reach British Whitworth Thread Barre
5、l1/2” Reach 5/8”-24 Thread Barrel3/8” Reach 5/8”-24 Thread Barrel18MM13/16” Reach 5/8”-24 Thread Barrel13/16” Reach 3/4”-20 Thread Barrel1/2” Reach 5/8”-24 Thread Barrel1/2” Reach 3/4”-20 Thread Barrel1/2” Reach Unshielded3. APPLICABLE DOCUMENTS :3.1 The following documents shall form a part of this
6、 specification to the extent specified herein. The applicable issue of each shall be that in effect on the date of the Aerospace Standard unless otherwise agreed between manufacturer and purchaser. Supplementary specifications, standards, etc., which by reference in any of the following publications
7、 are indicated to be part thereof, shall not be considered as effective except as specifically stated in the manufacturers detail specification or as may be otherwise mutually agreed upon between the manufacturer and the purchaser.AS 28BPage 2DrawingsAS 368 Spark Plug Thread Form DataARP 590 Spark P
8、lug - Aircraft Reciprocating EngineAS 678 Gasket - Folded Steel Spark PlugAN 4027 Gasket - Spark PlugAND 10219 Spark Plug - 14MM British Type ShieldedSpecificationsMIL-F-5572 Gasoline Aviation, Grades 80/87, 91/96, 100/130, 115/145MIL-C-6529 Compound - Aircraft Engine Corrosion PreventiveMIL-E-25111
9、 Engines - Aircraft - Reciprocating - Qualification Tests for4. REQUIREMENTS :4.1 Strength : The spark plug shall be capable of withstanding an installation torque of 75 foot-pounds for 18MM spark plugs and 55 foot-pounds for 14MM spark plugs without permanent distortion or development of gas leakag
10、e in excess of that allowed in Paragraph 5.2.6. For this test, the threads shall be lubricated with Corrosion Preventive Compound, MIL-C-6529 Type III.4.2 Gap Design and Setting : The gap between the electrodes of the spark plug shall be as specified by the procuring agency. The gap shall not contra
11、ct or expand sufficiently at maximum engine operating temperature to interfere with engine operation. The design of the gap shall be such that electrodes can be reset when the gap becomes too wide for satisfactory operation. Electrode design shall be such that spark plugs can be satisfactorily clean
12、ed and serviced.4.3 Interchangeability : All removable parts of spark plugs of the same type and model shall be interchangeable with corresponding parts furnished by the same vendor.4.4 Screw Threads : All threaded connections used in the construction of spark plugs except internal threads shall con
13、form to screw thread standards listed in the latest issue of AS 368 and the requirements of the applicable drawing.4.5 Lubrication - Threads : Unless otherwise specified, a thin coating of corrosion preventive compound conforming to Specification MIL-C-6529, Type III, shall be applied to the threads
14、 of each spark plug before shipment.4.6 Packaging : Spark Plugs shall be so packed as to insure that no damage will accrue to the spark plug threads or internal parts during shipment.4.7 Gasket : Unless otherwise specified, each spark plug shall be furnished with a solid copper gasket of the appropr
15、iate size as listed in AN 4027 drawing. When specified, each 18MM spark plug shall be furnished with a gasket conforming to AS 678.AS 28BPage 34.8 Markings : Each spark plug shall be permanently and legibly marked to contain the following information:Manufacturers NameManufacturers Type Designationa
16、nd Latest Change LetterDate Code Indicating Date of Manufacture4.8.1 Markings may appear on either the shielding barrel or shell hexagon of shielded plugs and on the insulator, shell or shell hexagon of unshielded plugs, or packaging identification (of gap setting only).4.9 Dimensions : Spark plugs
17、shall be in accordance with the dimensions shown on the applicable drawings unless otherwise specified.4.10 Performance Limits : The design of the spark plug shall be such that operation at temperatures up to those producing preignition and after firing shall be possible without material or structur
18、al failure for a period of time equal to that required during the prescribed heat rating test.5. QUALIFICATION TESTS : These tests shall be conducted by or at the direction of the purchaser unless otherwise agreed upon between the purchaser and the manufacturer.5.1 Samples : Samples for qualificatio
19、n test shall consist of three complete sets of plugs for the engines in which the manufacturer desires qualification.5.2 Tests :5.2.1 Examination of Product : Each spark plug shall be carefully examined externally to determine conformance with this specification with respect to material, workmanship
20、 and general requirements.5.2.2 Resistor Test : Each spark plug shall be checked for stability of internal resistance and/or contact by measurement of the center wire resistance by the use of a low voltage ohmmeter (8 volts or less). Center wire resistance values of any spark plug which has been sub
21、jected to engine operation shall be within the limits of plus 100% or minus 50% of the values listed by the spark plug manufacturer. Any spark plug showing a resistance value outside of the above-specified limits must pass a reference test utilizing a 1000-volt megger ohmmeter. The above limits shal
22、l apply for the referee test.5.2.3 Electrical Test of Insulator : Each spark plug insulator shall be tested before assembly for electrical breakdown at a voltage of not less than 15 KV peak. The voltage shall be impressed so that the entire periphery of the ceramic is subjected to the electrical pot
23、ential.5.2.4 Electrical Testing of Shielding Barrel Insulators - Two-Piece Insulator Only : Each insulator used in the shielding barrel of a shielded plug shall be tested before assembly in accordance with Insulator Test 5.2.3.AS 28B Page 45.2.4 Electrical Testing of Shielding Barrel Insulators - Tw
24、o-Piece Insulator Only : (Continued)In this case, a mandrel shall be used instead of the center electrode, with sufficient voltage applied to cause sparking over the insulator sleeve between the mandrel and test fixture ring; no sparking shall occur through the insulator sleeve. Any evidence of brea
25、kdown shall be cause for rejection.5.2.5 Dielectric Test : There shall be no indication of insulation breakdown when the assembled plugs are tested with the gaps extinguished for three seconds and a minimum potential equivalent to 9,000 volts (rms) is applied to the center electrode. If there is ind
26、ication of failure, further checks shall be made to determine that shielding barrel flashover has not occurred because of foreign matter or high humidity. Flashover of clean, dry, shielding barrel insulators shall not be cause of rejection.5.2.6 Gas leakage : Each spark plug shall be installed in a
27、pressure bomb at room temperature and the firing end subjected to a gas pressure of 800 psi. The rate of leakage through the plug shall not exceed 20 cc. in a five-minute period. For this test the spark plugs shall be installed with the threads lubricated with 1010 oil, and they shall be torqued in
28、at 36 ft. lb. An approved gasket shall be used at the spark plug seat.5.2.7 Heat Rating Tests :5.2.7.1 For Qualification Test : When spark plugs are submitted for Qualification Test, the number of plugs to be subjected to the heat rating test shall be at least one-half of the number required for the
29、 type of engine for which the spark plugs are to be qualified but not less than ten. The spark plugs shall be installed in a cylinder head designed for the particular thread length of spark plug to be rated. No spacers of a thickness other than that of a standard gasket may be permitted under the ga
30、sket seat. A description of the above test engine can be secured from the manufacturer (Laboratory Equipment Corporation, Mooresville, Indiana). The test procedure and engine operation conditions shall be as specified in the SAE Recommended Practice, “Preignition Rating of Spark Plugs for Ground Veh
31、icles” in the latest issue of the SAE Handbook. The individual ratings of a given lot of spark plugs shall be within 90% and 110% of the average of all the ratings of the lot. If one or more samples is not within 90% and 110% of the average, a duplicate set of specimens shall be obtained and rated.
32、If the second group of samples is within 90% and 110% of the average ratings, the spark plugs may be accepted. If samples of the second lot are not within 90% and 110% of the average of all the ratings, the procuring agency will consult with the manufacturer to determine the action to be taken. When
33、 the average rating of the new spark plug is being established during the Qualification Test, that rating shall be agreed upon by the testing agency and the manufacturer.AS 28BPage 55.2.7.2 For Inspection Tests : Samples selected in accordance with Paragraph 7.1 shall be subjected the heat rating te
34、st. Test procedure and requirements for individual ratings shall be the same as described in Paragraph 5.2.7.1 above.5.2.8 Tests After Heat Rating : Upon completion of the Heat Rating Tests, the plugs shall be subjected to the following tests in the order shown:Paragraph 5.2.5 . . . . . . . . . . .
35、. . . . . . . . . . . . . . Dielectric TestParagraph 5.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . Resistor TestParagraph 5.2.6 . . . . . . . . . . . . . . . . . . . . . . . . . Gas Leakage TestParagraph 5.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . Examination of ProductBefore t
36、he above tests are conducted, the spark plugs should be examined to see that the firing ends are not covered with carbon or oil deposits. If deposits are present, the spark plugs should be cleaned before these tests. Failure of the spark plugs to satisfactorily pass the above tests may be cause for
37、rejection.5.3 Ground Endurance Test : A Ground Endurance Test of at least 150 hours shall be completed with plugs installed in approximately one-half the cylinders of a service engine. Plugs of an approved type shall be installed in the remaining cylinders. All spark plugs, both for which qualificat
38、ion is desired and the approved spark plugs, shall either have the gaps set accurately to .001“ tolerance or a record shall be made of all gaps at the time of installation. The tests shall be conducted in accordance with the 150-hour endurance run for the particular type of engine as outlined in Spe
39、cification MIL-E-25111 using fuel recommended for the particular engine being used. The fuel shall contain the maximum amount of tetraethyl lead as permitted under Specification MIL-F-5572. The specific fuel consumption shall be maintained within limits of plus 3, minus 0 percent of the minimum guar
40、anteed values specified in the engine model specification for the corresponding powers and speeds. After the Ground Endurance Test, the average increase in the gap between the electrodes shall be determined at room temperature. If this increase is greater for the test plugs than for the approved plu
41、gs, the plug model under test may be rejected. If engine malfunction is experienced which is attributable to premature failure of the spark plug prior to the completion of the 150-hour model test, this shall be reason for rejecting the test spark plugs.5.3.1 Tests After Ground Endurance : Upon compl
42、etion of ground endurance testing, plugs shall be subjected to the following tests in the order shown:Paragraph 5.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . Dielectric TestParagraph 5.2.2 . . . . . . . . . . . . . . . . . . . . . . . . . Resistor TestParagraph 5.2.6 . . . . . . . . . . .
43、. . . . . . . . . . . . . . Gas Leakage TestParagraph 5.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . Examination of ProductFailure of the plugs to satisfactorily pass the above tests may be cause for rejection.AS 28BPage 65.4 Fouling Tests : Fouling characteristics shall be determined by ma
44、king comparative tests in an aircraft engine under conditions conducive to fouling. Qualification test samples and spark plugs of an approved design shall be installed in the same engine. Spark plug fouling may be determined by the use of an ignition analyzer. If the qualification test samples indic
45、ate a greater amount of fouling than the approved spark plugs of a comparable heat rating, the spark plugs may be rejected.5.5 Flight Service Tests : If the engine selected by the purchaser for the flight service tests is used in only one type of airplane, this test shall be made in that installatio
46、n only. If the engine is used in different types of airplanes, tests may be made in more than one type of airplane at the discretion of the purchaser. If engine malfunction is experienced which is attributable to premature failure of the spark plug prior to the time specified in 5.5.1(b), this shall
47、 be reason for rejecting the plugs.5.5.1 Flight Operating Conditions : A complete set of new plugs shall be installed in one or more engines of each aircraft in which the flight test is to be conducted. Each flight test shall consist of two phases as follows:(a) A rated-power climb of five minutes t
48、o the attained altitude, one-half hour of cruising at this altitude to allow engine operating conditions to stabilize, a glide with throttle closed for approximately two minutes, followed by level flight at cruising output to check the plugs. (b) Routine flights or modifications of the type of fligh
49、t described in “a” above until a total time of flight endurance has been completed as specified by the purchaser. A record shall be kept of the performance of the plugs, and fouled or defective plugs shall be replaced.If performance is abnormal or if excessive malfunctioning of the qualification test plugs is encountered, the model undergoing test may be rejected.5.5.2 Tests After Flight Service Tests : Upon completion of the Flight Service Tests, spark plugs shall be subjected to the following tests in the order shown:Paragraph 5.2.5 . . . . . . . . . . . . . . . . . . . . . . . . . Die
