1、MIL-S-812D 3b 977970b 0387975 MIL-S- 881 2D 3 September 1975 SUPERSEDING 16 January 1969 MIL- S-8812C MILITARY SPECIFICATION STEERING SYSTEM: AIRCRAFT, GENERAL REQUIREMENTS FOR This specification is approved for use by all Departments and Agencies of the Department of- Defense. 1. SCOPE 1.1 cyst ems
2、. This specification covers the general requirements for aircraft steering 2. APPLICABLE DOCUMENTS 2.1 for bids or requests for proposal, form a part of this specification to the The following documenp, of the issue in effect on the date of invitation extent specified herein: SPECIFICATIONS Federal
3、QQ- C- 32 O Chromium lating (Electrodepositec QQ- N- 290 Nickel Plating (Electrodeposited) QQ- P- 41 6 QQ-2-325 Mi 1 it ary MIL-D-1000 MIL-S-4040 MIL- W- 5088 MIL-E-5400 MIL-H-5440 MI L- C- 5503 MIL- P- 551 8 MI L-V- 5529 MI L-H-5606 Plating Cadmium (Electrodeposited) Zinc Coating, Electrodeposited,
4、 Requirements for Drawings, Engineering and Associated Lists Solenoid, Electrical, General Specification for Wiring, Aircraft, Selection and Installation .of Electronic Equipment, Airborne, General Specification for Hydraulic Systems, Aircraft, Types I and II, Design, Installation, and Data Requirem
5、ents for Cylinders, Aeronautical, Hydraulic Actuating, General Requirements for Pneumatic Systems, Aircraft, Design, Installation, and Data Requirements for . Valves, Hydraulic Directional Control Hydraulic Fluid, Petroleum Base, Aircraft, Missile and Ordnance A Provided by IHSNot for ResaleNo repro
6、duction or networking permitted without license from IHS-,-,-MIL- S- 88 12D MIL-R- 5757 MIL-R- 61 06 MIL-P- 8564 MIL-A-8625 MIL-H-8775 MIL- F- 8785 MIL-A-8860 MIL-H-8890 MI L-H- 8891 MIL- A- 8892 MI L-T- 1072 7 MIL- V- 2 71 62 MIL- C- 38999 MIL-W- 81381 STANDARDS Mi 1 it ary MIL-STD-100 MI L- STD- 1
7、 2 9 MIL-STD- 130 MIL-STD-143 MIL- STD- 203 MI L-STD-461 MIL-STD-462 MIL-STD-704 MIL-STD-794 MIL- STD- 810 MI L- STD- 8 3 1 MIL-STD-882 MIL- STD- 8 8 9 MIL-STD- 1523 2 Relays, Electrical (For Electronic and Communication Type Equipment), General Specification for Relays, Electric, Aerospace, General
8、 Specification for Pneumatic Systems Components, Aeronautical, General Specification for Anodic Coatings, for Aluminum and Aluminum Alloys Hydraulic System Components, Aircraft and Missiles, General Specification for Flying Qualities of Piloted Airplanes Airplane Strength and Rigidity, General Speci
9、fication for Hydraulic Components, Type III (-65 to +450F), General Specification for Hydraulic Systems, Manned Flight Vehicles, Type III, Design, Installation, and Data Requirements for Aircraft Strength and Rigidity, Vibration Tin Plating; Electrodeposited or Hot-Dipped, for Ferrous and Nonferrous
10、 Met als Valves, Servo Control, Electro-Hydraulic, General Specification for Connectors, Electrical, Circular, Miniature, High Density, Quick Disconnect, Environmental Resisting Removable Crimp Type Contacts, Reliability Assurance Program Wire, Electric, Polyimide-Insulated, Copper and Copper Alloy
11、Engineering Drawing Practices Marking for Shipment and Storage Identification Marking of US Military Property Standards and Specifications, Order of Precedence for the Selection of Aircrew Station Controls and Displays: Assignment, Location and Actuation of, for Fixed Wing Aircraft Electromagnetic I
12、nterference Characteristics Requirements for Equipment Electromagnetic Interference Characteristics, Measurement of Electric Power, Aircraft, Characteristics and Utilization of Parts and Equipment, Procedures for Packaging and Packing of Environmental Test Methods Test Reports, Preparation of System
13、 Safety Program for Systems and Associated Subsystems and Equipment - Requirements for Dissimilar Metals AGE Control of Age - Sensitive Elastomeric Materiel Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-8832D Ib 9999906 0387977 3 MIL-S-8812D
14、(Copies of specifications, standards, drawings, and publications required by suppliers in connection with specific procurement functions should be obtained from the procuring activity or as directed by.the contracting officer.) 3. REQUIREMENTS 3.1 Preproduction testing. This specification makes prov
15、isions for prepro- duction testing. The preproduction testing defined herein is the minimum testing requirement. completion of these tests and the tests specified in the detail specification including satisfactory demonstration on the intended aircraft. 3.1.1 Safety of flight. testing required befor
16、e release for first flight as specified in 4.3.2. Final design approval will be contingent upon successful Safety of flight is the minimum level of successful 3.2 Selection of specifications and standards. Specifications and standards for necessary commodities and services not specified herein shall
17、 be selected in accordance with MIL-STD-143. 3.3 Materials. high quality, suitable for the purpose intended, and shall conform to applicable Government specifications. Materials used in the steering system components shall be of 3.3.1 Dissimilar metals. The use of dissimilar metals in contact, as de
18、fined in MIL-STD-889, shall be avoided. Where complete compliance proves impractical electrolytic action shall be minimized by plating or some other suitable method of dissimilar surface isolation. 3.3.2 Corrosion resistance. Corrosion prevention shall be provided by proper material selection and tr
19、eatment. Protective treatment for hydraulic components shall be in accordance with MIL-H-8775. 3.4 Design and construction. Detail design and construction of the components and steering systems shall conform to the contractor prepared detail specifica- tion and the requirements specified herein. The
20、 components shall be suitably sealed against dust, dirt, and moisture to insure satisfactory operation in the aircraft environment. shaped to prevent water entrapment with gear extended. specified in the detail specification and shall be equal to the aircraft design life. the configuration of the ai
21、rcraft and shall be defined in the detailed specification. Where possible the external component parts shall be The useful life shall be The type of system as defined in 6.3.1 and 6.3.2 shall be compatible with 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
22、om IHS-,-,- the interface requirements of the applicable aircraft including the following: a. b. c. Dynamic characteristics including the tire(s), wheel(s), shock strut, and supporting structure Aircraft directional control response characteristics Aircraft hydraulic and mechanical installation d. D
23、imensional and envelope interface e. Aircraft operational environment. permit turning the steered wheels through the full range without the aid of motion of the aircraft or engine thrust or auxiliary power. Unless a rational alternative is approved by the procuring activity, the steering capability
24、shall be available throughout the design temperature range of the aircraft, and with the most critical combination of weight and center of gravity at engine idle thrust and a design coefficient of friction of 0.80 at the tire ground interface, The tires shall be inflated in accordance with applicabl
25、e servicing instructions, and all brakes may be assumed to be released unless normal engine idle thrust is sufficiently high to cause motion. smooth handling at landing and takeoff speeds and- minimize pilot induGd oscilla- tion. The system shall also give sufficient response at taxiing speeds to pe
26、rmit the necessary rate for small radius turns, parking, catapult spotting, and close quarters operat*ion. be demonstrated by early taxi tests and results submitted to,the procuring activity. The suitability of the selected steering rate and ratio shall shall have full time steering authority design
27、ed to obtain the maximum tire cornering angle, with a pilot selected wide authority mode available to the authority limits as specified in 3.4.2.3.1 or 3.4.2.3.2 as applicable. requirement is intended to provide more consistent aircraft directional control and to better utilize the available tire co
28、rnering forces. cornering angle shall be based upon the best available tire cornering data and shall be approved by the procuring activity. This The maximum tire Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-LZD 36 9999906 0387979 5 9 MIL-S-
29、8812D 3.4.2.3.1 Carrier based aircraft. Carrier based aircraft with nose wheel steering shall meet the powered steering angles as shown on figure 1. 3.4.2.3.2 Land based aircraft. Land based aircraft shall provide powered steering angles sufficient to enable a 180 degree turn on a runway width as de
30、fined in the aircraft detail specification. 3.4.2.4 Free swivel range. Provisions shall be incorporated on all land based aircraft to permit free swiveling to the limits of figure 1 consistent with the aircraft geometry. All carrier based aircraft shall be designed to permit 360 free swiveling. Any
31、free swiveling range shall not require manual disconnect of any parts or linkages unless otherwise directed by the procuring activity. An automatic disconnect is permitted to turn the wheel beyond the power steering range however automatic re-engaging provisions shall be provided as the wheel re-ent
32、ers the powered steering range. 3.4.2.5 Steered wheel centering. configuration shall provide wheel(s) centering before retraction. The following nose wheel centering features shall be provided for carrier-type nose wheel steering aircraft: The steering system or the landing gear a. The nose wheel sh
33、all be steerable during the runout of an arrested landing. b. The nose wheel shall remain centered unless commanded otherwise by the pilot during the roll back due to cable tension after arrestment. Actuation of steering shall be possible regardless of arresting with position to enable steering duri
34、ng a field arrestment. 3.4.2.6 Input force limits. The control forces shall be in accordance with MIL-F-8785. 3.4.2.7 Dynamic stability and damping provisions. The steering system shall provide dynamic and damping stability to the nose landing gear for all ground speeds from zero to 1.3 Vsl (takeoff
35、 or landing configuration, whichever is greater) in accordance with MIL-A-8860. This shall be verified by analysis and test for all speed and vertical loading combinations of the nose landing gear, for the cases of steering power ON and with steering power failed or OFF, and for the extremes of the
36、manufacturing tolerances for those parameters defined in the detail specification. The system shimmy stability requirements shall be determined by a non-linear dynamic analysis properly accounting for deadband, friction, wheel unbalance, and realistic damping characteristics. Excitation of the shimm
37、y conditions shall include impulse, cyclic and initial displacements of the nose landing gear. The steering system shall provide sufficient damping to reduce the shimmy oscillation amplitude after three cycles to 1/4 or less of the original disturbance. If limit cycle is encountered, Provided by IHS
38、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL- S- 881 2D I I l + I i I Laai o Ins L 3- I I ;I . m m Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-L2D Lb 7997706 0387783 3 m MIL-S- 881 2D the maximum am
39、plitude is subject to approval by the procuring activity. design component parameters used for the shimmy analysis shall be verified by demonstration laboratory tests. analysis shall be verified by ground vibration test on the aircraft in accord- ance with MIL-A-8892, prior to first flight. In the e
40、vent the physical charac- teristics on the aircraft are different from those used in the shimmy analysis, the analysis shall be repeated for the corrected values. The analysis shall be continued to include freedom due to wear, with all surfaces worn to the maximum permissible amount and with the mas
41、t adverse servicing of tires and shock absorbers permitted by aircraft technical publications. motion shall decay after three cycles to 1/3 or less of the original disturbance after the excitation cited above. For USAF aircraft, these damping requirements apply to the nose landing gear and to the ma
42、in gear design criteria. 3.4.2.8 Cockpit controls. Cockpit controls including provisions for commanding the steered wheel position and a means for engaging or disengaging the steering system, if applicable, shall be provided in accordance with MIL-STD-203 as amended by this specification. 3.4.2.8.1
43、Cockpit controls - Class A control steering systems. Aircraft equipped with Class A control steering systems shall command the limited authority mode by rudder pedal position. The wide authority mode shall be commanded by a steering wheel on transport aircraft and with the rudder pedals on fighter/a
44、ttack/carrier based aircraft with suitable switching arrangement and cockpit engagement status light subject to procuring activity approval. rapidly disengage the Class A control steering system. 3.4.2.8.2 Cockpit controls - Class B control steering systems. Aircraft equip- ped with Class B control
45、steering systems shall utilize the rudder pedal to command the steered wheel position and shall be engaged at the option of the pilot. On all stick controlled aircraft, a (press to engage, press to disengage, engage when depressed) switch shall be provided and shall have a steering engaged status li
46、ght. The The system parameters used in the shimmy For these conditions the shimmy Provisions shall be made to 3.4.2.9 Steering control system. wheel at the commanded position or tire cornering force level as applicable for the system servo concept selected (defined in 6.3.3). follow-up control linka
47、ge is preferred. tronic control systems shall not be used for steering systems (defined in 6.3. i). The steering system shall maintain the steered A mechanical input and Single channel electrical and elec- 3.4.2.10 i.e. (fail operative, fail safe - inoperative), shall be compatible with aircraft req
48、uirement and as approved by the procuring activity. result in undesirable steering effects that cannot be overcome by normal and natural application of the steering cockpit controls. Failure mode and malfunction effects. The system design failure mode, No single failure shall The system design failu
49、re Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S- 88121) mode shall not require pilot interpretation and action to disengage the system upon failure. with the required motion of the rudder pedals, flight controls or prevent shimmy stability. The steering system shall be so designed that steering system mal- function, such as a failed hydraulically open selector valve can
