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4、(outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AIR5914AEROSPACEINFORMATION REPORT AIR5914Issued 2014-06 Landing Gear Fatigue Spectr
5、um Development For Part 25 Aircraft RATIONALEThis document provides a means for deriving a spectrum of loads for assessing the life of a main and nose landing gear for Part 25 tricycle landing gear structural components. Many of the recommendations herein are generalizations based on data obtained f
6、rom a wide range of landing gears.FOREWORDThis SAE Aerospace Information Report (AIR) provides recommendations for the derivation of analytical fatigue spectra for the design and qualification of landing gear structural components and the relevant actuation systems for Part 25 tricycle landing gear
7、configuration. TABLE OF CONTENTS 1. SCOPE 31.1 Purpose . 32. REFERENCES 32.1 Applicable Documents 32.1.1 Military . 32.1.2 Regulatory Requirements . 42.1.3 Standards 42.1.4 Other Publications . 42.2 Terminology 53. GENERAL . 64. SERVICE LIFE 65. GENERAL REQUIREMENTS . 65.1 Typical Flight Profile 65.
8、2 Scatter Factor 65.3 Aircraft Mission Profile 75.3.1 Method 1 . 75.3.2 Method 2 . 75.3.3 Method 3 . 76. LANDING CONDITIONS 86.1 Landing Impact 86.2 Landing Impact with Drift Landing. 96.3 Torsion Due to Asymmetry of the Drag Forces 106.4 Additional Landing Conditions 10SAE INTERNATIONAL AIR5914 Pag
9、e 2 of 18 7. GROUND MANEUVERING 107.1 General . 107.2 Taxiing . 107.3 Turning 117.3.1 Turning Cases Consideration for Truck/Bogie Beam . 117.4 Braking 117.4.1 Maximum Braking Effort 117.4.2 Anti-Skid Effort 127.5 Pivoting . 127.5.1 Commercial Aircraft with Two Main Wheel Gear Shock Strut Configurati
10、on 127.5.2 Slow Turn Cases Consideration for Truck/Bogie Beam . 137.6 Engine Run-Up 137.7 Steering Spectrum 137.8 Push Back and Nose Gear Towing . 147.8.1 Conventional Towbar Towing . 147.8.2 Towbarless Towing . 158. FREE EXTENSION/REBOUND (TAKEOFF TRANSITION) 169. FLIGHT LOADINGS (GUST AND MANEUVER
11、ING LOADS) 1610. SUSTAINED ENGINE IMBALANCE CONDITIONS (IE. WIND MILLING ENGINE ANDBLADE OUT VIBRATION CONDITIONS) 1711. EXTENSION, RETRACTION, AND BRAKING WHEELS IN AIR . 1711.1 Braking Wheels in Air 1711.2 Gear Retraction and Extension . 1712. INTERNAL PRESSURES . 1713. GROUND-AIRGROUND CYCLES . 1
12、814. NOTES 18TABLE 1 DISTRIBUTION OF DESCENT RATE PER 1000 LANDINGS . 9TABLE 2 TAXING LOADS AND OCCURRENCES . 10TABLE 3 TURNING SIDE LOAD LOADS AND OCCURRENCES 11TABLE 4 MLG BRAKING LOADS AND OCCURRENCES 12TABLE 5 NLG REACTIVE LOADS AND OCCURRENCES DUE TO MLG BRAKING . 12TABLE 6 ENGINE RUN-UP . 13TA
13、BLE 7 NLG STEERING APPLICATIONS 14TABLE 8 TOWBARLESS TOWING FATIGUE SPECTRUM . 16TABLE 9 FREE EXTENSION . 16TABLE 10 GUST AND MANEUVER “G” LOADS 17SAE INTERNATIONAL AIR5914 Page 3 of 18 1. SCOPE This SAE Aerospace Information Report (AIR) provides guidelines for the development of landing gear fatig
14、ue spectra for the purpose of designing and certification testing of Part 25 landing gear. Many of the recommendations herein are generalizations based on data obtained from a wide range of landing gears. The aircraft manufacturer or the landing gear supplier is encouraged to use data more specific
15、to their particular undercarriage whenever possible. 1.1 Purpose With the ever-increasing length of aircraft operating life, design for good fatigue resistance assumes greater prominence, particularly for civil aircraft with low reaction factors where landing loads are assumed to have little signifi
16、cance. In recent years, the ability to gather field data on actual aircraft landing gear loading has allowed aircraft manufacturers todevelop large data sets for use in developing fatigue spectra for new aircraft. This spectrum generally varies with the type of aircraft such as military versus comme
17、rcial, as well as the various configurations of commercial aircraft from wide body transports to regional aircraft and business jets. In most cases, in the past the aircraft manufacturer has provided the fatigue spectrum in the design specification. This has ranged from block loads for similar maneu
18、vers to the modern flight-by-flight spectrum. In cases where the fatigue spectrum is not provided, a standardized method of developing the fatigue spectrum is needed. This methodology can be used by landing gear supplier to develop the fatigue spectrum based on a set of parameters supplied by the ai
19、rcraft manufacturer. The purpose of this document is to establish guidelines for the landing gear supplier to develop Landing Gear Fatigue Spectra (LGFS) from loads data supplied by the aircraft manufacturer or with no data supplied by the manufacturer. It is the intent to base the recommendations f
20、or the various aircraft configurations upon historical data used in landing gear design as well as input from the aircraft manufacturers and in some cases, the aircraft users. Individual landing gear units may be initially designed and qualified to fatigue requirements in excess of those stated in t
21、his report. This maybe for a variety of reasons such as: a. Simplifying analysis and testing. b. Ensure adequate life availability for future increased weight versions of the airplane. This report addresses the fatigue load spectrum requirements of the landing gear. Requirements in addition to those
22、 of this report may be imposed to verify functional and endurance aspects of the gears. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publi
23、cations shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific
24、exemption has been obtained. 2.1.1 Military 2.1.1.1 MIL-A-8866, Airplane Strength and Rigidity Requirements, Repeated Loads, Fatigue and Damage Tolerance 2.1.1.2 MIL-S-8812D, Steering System: Aircraft General Requirements For 2.1.1.3 MIL-L-8552C, Landing Gear, Aircraft Shock Absorber SAE INTERNATION
25、AL AIR5914 Page 4 of 18 2.1.2 Regulatory Requirements 2.1.2.1 FAR 14 CFR Part 25, Federal Aviation Administration, Department of Transportation Part 25-Airworthiness Standards: Transport Category Airplanes2.1.2.2 EASA CS 25, European Aviation Safety Agency Certification Specifications for Large Airp
26、lanes CS-25 2.1.2.3 NPA No. 2011-09, Notice of Proposed Amendment (NPA) No 2011-09, “Incorporation of generic SC and AMC CRIs in CS-25”, May 2011. 2.1.3 Standards2.1.3.1 ARP1383, Aerospace - Impulse Testing of Hydraulic Components 2.1.3.2 AIR1489, Aerospace Landing Gear Systems Terminology 2.1.3.3 A
27、RP5429, Landing Gear Fatigue Tests with Equivalent Damage Spectra 2.1.3.4 AS8860, Landing Gear Structural Requirements as Listed in the MIL-886X Series of Specifications 2.1.4 Other Publications2.1.4.1 Royal Aircraft Establishment Library Translation No. 1462, Cumulative Frequency Distribution of Ai
28、rcraft Landing Gear Loads, O. Buxbaurn and E. Gassner 2.1.4.2 Engineering Sciences Data Unit (ESDU) 75008, Frequencies of Vertical and Lateral Loads Factors Resulting from Ground Maneuvering of Aircraft 2.1.4.3 Advisory Group for Aeronautical Research and Development (AGARD), Report No. 118, A Revie
29、w of Landing Gear and Ground Loads Problems, J.F. McBearty 2.1.4.4 DEF-STAN-00-970, Leaflet 41, Part 1 Section 4, Issue 2, Dec 1999, Fatigue Loads Spectra for Main Undercarriage Units, Design of Undercarriages-General Requirements, Fatigue Load Spectra for Main Undercarriage Units 2.1.4.5 NASA Techn
30、ical Note TN D-4586, Trends in Repeated Loads on Transport Airplanes, Coleman, Thomas L. 2.1.4.6 Aeronautical Fatigue: Key to Safety and Structural Integrity, Loads at the Nose Landing Gears of Civil Transport Aircraft During Towbarless Towing Operations, G. Buxbaum, J.J. Cuny, H. Klatschle, H. Stei
31、nhilber 2.1.4.7 DOT/FAA/AR-97/106, Video Landing Parameter Survey Washington National Airport (DCA):June 1995 2.1.4.8 DOT/FAA/AR-00/72, Video Landing Parameter Survey - Honolulu International Airport, May 2001 2.1.4.9 18thAnnual Airport Conference, March 1995, Landing Survey Discussions of Landing P
32、arameter Data for Typical Transport Operations 2.1.4.10 UDR-TR-2002-00108, Statistical Loads Data for Bombardier CRJ200 Aircraft In Commercial Operations, University of Dayton Research Institute 2.1.4.11 DOT/FAA/AR-02/35, Statistical Loads Data for the Airbus A-320 Aircraft in Commercial Operations,
33、 April 2002 2.1.4.12 DOT/FAA/AR-00/10, Statistical Loads Data for B-767-200ER Aircraft in Commercial Operations, March 2000 2.1.4.13 DOT/FAA/AR-98-65, Statistical Loads Data for MD-82-83 in Commercial Operations, February 1999. 2.1.4.14 DOT/FAA/AR-00/11, Statistical Loads Data BE-1900D Aircraft in C
34、ommuter Operations, April 2000 SAE INTERNATIONAL AIR5914 Page 5 of 18 2.1.4.15 DOT/FAA/AR-02/129, Side Load Factor Statistics from Commercial Aircraft Ground Operations, January 2003 2.1.4.16 AGARD Conference Proceedings 484, Landing Gear Design Loads; October 1990. 2.1.4.17 DOT/FAA/AR-98/28, Statis
35、tical Loads Data for Boeing 737-400 Aircraft in Commercial Operations, August 1998.2.2 Terminology CG Center of Gravity Dmax, Dmin Maximum/Minimum Drag Load EASA European Aviation Safety Agency FAR Federal Aviation Regulations Ftow Towing Load applied in the Horizontal Direction JAR Joint Airworthin
36、ess Requirements LGFS Landing Gear Fatigue Spectra MAC Mean Aerodynamic Chord MLG Main Landing Gear NLG Nose Landing Gear RR Tire Rolling Radius (Dynamic) TLR Tire Loaded Radius RTO Rejected Takeoff Smax, Smin Maximum/Minimum Side Loads SF Scatter Factor SSVP Shock Strut Vertical Position VAT Vertic
37、al Axle Travel VBR1NLG reaction load for the corresponding MLG Vertical and Drag Load during Medium Braking VBR2NLG reaction load for the corresponding MLG Vertical and Drag Load during Maximum Braking V Vertical Load VDMLG/NLG vertical load at the design maximum descent rate VdrAircraft Descent Rat
38、e VST MLG/NLG Static Vertical Load at the prescribed weight usage Wl Landing Weight Wr Ramp Weight SAE INTERNATIONAL AIR5914 Page 6 of 18 3. GENERAL The structural design of the landing gear is such that repeated loads do not cause failure or permanent deformation of any part of the landing gear, in
39、terfere with its mechanical operation, or affect its aerodynamic characteristics. Further, the design does not require repair, inspection, or replacement of components other than as specifically approved by the contracting activity. The above requirements apply to the planned service life of the air
40、plane for the repeated loads environment resulting from ground and flight operations.4. SERVICE LIFE The service life of the airplane should not be less than that specified by the contracting activity in terms of the following (as applicable): 1. Flight hours 2. Ground-air-ground cycle (flights) 3.
41、Taxi runs 4. Takeoff runs 5. Landings 5. GENERAL REQUIREMENTS 5.1 Typical Flight Profile The fatigue life requirements are specified in terms of airplane flights. One airplane flight is defined, in sequence of ramp-to-ramp events, which includes pushback/towing, taxi out, takeoff run, liftoff, gear
42、retraction, cruise, gear extension, touchdown, landing rollout, and taxi in.5.2 Scatter Factor The life requirements for the landing gear structure should be specified in number of airplane flight hours or flight cycles with a relationship between airplane flight hours and number of landings.Appropr
43、iate life scatter factors (SF) should be used for analysis and test.Fatigue design life implies the average life expected under average aircraft utilization and loads environment. To this design life, application of a scatter factor accounts for the typical variations from the average utilization, l
44、oading environments, and basic fatigue strength allowable. This leads to a safe-life period during which the probability of a detectable structural crack occurring is very low. Scatter factors ranging from four to five have been used to account for statistical variation in component fatigue tests an
45、d unknowns in loads. Load unknowns involve both methods of calculation and type of service actually experienced.CFR 14 Part 25 AC 25.571 and EASA AMC 25.571 present guidance in determining the scatter factor. SAE INTERNATIONAL AIR5914 Page 7 of 18 5.3 Aircraft Mission Profile The ground loading of t
46、he landing gear is a function of the weight carried by the gear. The design of the gear ought to withstand the full variation of possible gear loads during the design life of the landing gear without crack initiation. The variation of gear loads, due to the variation of the aircraft takeoff and land
47、ing weight, is such that it is not possible to define a weight that meets the design aims for all possible aircraft use. There will always be some difference in weight and CG position from mission to mission for both takeoff and landing. Unless provided by the aircraft manufacturer, three methods ar
48、e provided that cover the operational spread of aircraft weights. Method selection will need due consideration for aircraft applicability.5.3.1 Method 1 In general, it will be acceptable to use an average takeoff weight and CG position for takeoff and similarly an average landing weight and CG position for landing for aircraft that are primarily operating within a known mission. However, there will always be some difference in weight and CG position from mission to mission for both takeoff and landing. A flight mission can be short, medium
