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SAFE-LIFE LIMITS FOR LANDING GEAR STRUCTURES

2018-04-26
WIP
AIR6949
This document describes the approaches taken to define safe-life limits for the management of fatigue in landing gear structures, and the substantiation of those limits through full-scale fatigue testing. The safe-life scatter factors considered in a range of military and civil regulatory standards are also reviewed.
Standard

Landing Gear Safety Criticap Processes

2018-02-28
WIP
AIR6813
There are a number of safety critical processes that are common to landing gear systems. A safety critical process (CSP) is a landing gearmaintenance manufacturing, repair or overhaul process which if ommitted or preformed incorrectly will cause failure of a safety citical item (CSI) in operation. A CSI is a landing gear item whose failure or omission will cause more than $1M in damage, serious injury or death. This AIR will define methods and modes of failure for CSPs based on experience.
Standard

Development and Qualification of Composite Landing Gears

2016-01-04
WIP
AIR5552A
This information report provides general guidance for the design considerations, qualification in endurance, strength and fatigue of landing gear using composite components as principle structural elements. The information discussed herein includes the development and evaluation of design data considering: the potential for imbedded manufacturing defects, manufacturing process variations, the component operating environment, potential damage threats in service, rework and overhaul, and inspection processes. This AIR mainly discusses the use of thick composites for landing gear structural components. Considerations and recommendations provided in this AIR may therefore differ greatly from considerations and recommendations found in widely accepted composite design references such as CMH-17 and Advisory Circulars such as AC 20-107(B).
Standard

Information on Hard Landings

2018-02-27
WIP
AIR5938A

This document provides information on the current practices used by commercial and military operators in regards to hard landings (or overload events designated as hard landings). Since detailed information on inspections would be aircraft specific, this AIR provides only a general framework. Detailed information and procedures are available in the maintenance manuals for specific aircraft.

Because hard landings potentially affect the entire aircraft, guidelines are listed here for non-landing gear areas. But, the primary focus of the document is the landing gear and related systems. The document may be considered to be applicable to all types of aircraft.

This document does NOT provide recommended practices for hard landing inspections, nor does it provide recommendations on the disposition of damaged equipment. Refer to ARP 4915 and ARP 5600.

Standard

Information on Hard Landings

2011-01-03
CURRENT
AIR5938
This document provides information on the current practices used by commercial and military operators in regards to hard landings (or overload events designated as hard landings). Since detailed information on inspections would be aircraft specific, this AIR provides only a general framework. Detailed information and procedures are available in the maintenance manuals for specific aircraft. Because hard landings potentially affect the entire aircraft, guidelines are listed here for non-landing gear areas. But, the primary focus of the document is the landing gear and related systems. The document may be considered to be applicable to all types of aircraft. This document does NOT provide recommended practices for hard landing inspections, nor does it provide recommendations on the disposition of damaged equipment. Refer to ARP 4915 and ARP 5600.
Standard

Landing Gear Switch Selection Criteria

1999-04-01
CURRENT
AIR5024
The scope of this document is to discuss the differences between electromechanical and proximity position sensing devices when used on landing gears. It also contains information, which may be helpful, when applying either type of technology after the selection has been made. The purpose is to help the designer make better choices when selecting a position-sensing device. Once that choice has been made, this document includes information to improve the reliability of new or current designs. It is not intended to replace recommendations from sensor manufacturers or actual experience, but to provide a set of general guidelines.
Standard

CRACK INITIATION AND GROWTH CONSIDERATIONS FOR LANDING GEAR STEEL WITH EMPHASIS ON AERMET 100

1997-06-01
HISTORICAL
AIR5052
Steel alloys, such as AF1410 (AMS 6527, UNS K92571) and AerMet 100 (AMS 6532), have been developed which have improved Fracture Toughness characteristics compared to the current landing gear steel alloy, 300M (AMS 6419 and AMS 6257, MIL-S-8844, UNS K44220). The 300M steel is the most widely used material in current landing gear designs. It has been successfully used in thousands of applications. The use of the 300M material necessitates a safe life design criterion where components are retired after one-fourth to one-sixth the laboratory test life. This criterion was established in part due to the relatively low fracture toughness of low-alloy steel in the 260 to 300 ksi strength range. The high fracture tough alloys give comparable strength levels with an increase in fracture toughness and better resistance to stress corrosion cracking. These alloys may make possible the consideration of new procedures for operation, maintenance, and inspection.
Standard

Mechanical Switch Usage for Landing Gear Applications

1989-10-04
CURRENT
AIR4077
This Aerospace Information Report (AIR) will examine considerations relative to the use of mechanical switches on aircraft landing gear, and present "lessons learned" during the period that these devices have been used.
Standard

AIRCRAFT TAIL BUMPERS

1984-09-01
HISTORICAL
AIR1800
This document covers the field of civilian, commercial and military airplanes and helicopters. This summary of tail bumper design approaches may be used by design personnel as a reference and guide for future airplanes and helicopters that require tail bumpers. Those described herein will consist of simple rub strips, structural loops with a wear surface for runway contact, retractable installations with replaceable shock absorbers and wear surfaces and complicated retractable tail landing gears with shock strut, wheels and tires. The information will be presented as a general description of the installation, its components and their functions.
Standard

Aircraft Tail Bumpers

1997-07-01
CURRENT
AIR1800A
This SAE Aerospace Information Report (AIR) covers the field of civilian, commercial and military airplanes and helicopters. This summary of tail bumper design approaches may be used by design personnel as a reference and guide for future airplanes and helicopters that require tail bumpers. Those described herein will consist of simple rub strips, structural loops with a wear surface for runway contact, retractable installations with replaceable shock absorbers and wear surfaces and complicated retractable tail landing gears with shock strut, wheels and tires. The information will be presented as a general description of the installation, its components and their functions.
Standard

Design, Development and Test Criteria - Solid State Proximity Switches/Systems for Landing Gear Applications

2001-10-01
HISTORICAL
AIR1810B
This document will examine the more important considerations relative to the utilization of "one piece", or integral electronics proximity switches, and "two piece", or separate sensor and electronics proximity switches, for applications on aircraft landing gear. In general, the recommendations included are applicable for other demanding aircraft sensor installations where the environment is equally severe.
Standard

DESIGN, DEVELOPMENT AND TEST CRITERIA - SOLID STATE PROXIMITY SWITCHES/SYSTEMS FOR LANDING GEAR APPLICATIONS

1986-07-09
HISTORICAL
AIR1810A
This document will examine the more important considerations relative to the utilization of "one piece", or integral electronics proximity switches, and "two piece", or separate sensor and electronics proximity switches, for applications on aircraft landing gear. In general, the recommendations included are applicable for other demanding aircraft sensor installations where the environment is equally severe.
Standard

Design, Development and Test Criteria - Solid State Proximity Switches/Systems for Landing Gear Applications

1983-09-01
HISTORICAL
AIR1810
This document examines the most important considerations relative to the use of proximity sensing systems for applications on aircraft landing gear. In general, the recommendations included are applicable to other demanding aircraft sensor installations where the environment is equially severe. The purpose of this SAE Aerospace Information Report (AIR) is to suggest specification, application, performance, and validation criteria for solid-state proximity sensing systems used for environmentally severe applications on aircraft landing gear.
Standard

Landing Gear Integrity Program

2016-03-17
WIP
ARP6412
The scope of the Landing Gear Integrity Programs (LGIP) Aerospace Recommended Practice (ARP) is intended to assist in the safe-life structural integrity management of the landing gear system and subsystems components. In addition, component reliability, availability, and maintainability is included in a holistic LGIP.
Standard

Gland Design: Scraper, Landing Gear, Installation

2001-04-01
HISTORICAL
AS4052A
This SAE Aerospace Standard (AS) covers an alternate gland design for the installation of scraper/wiper rings in the lower end of landing gear shock struts for the purpose of contaminant exclusion. The defined scraper gland covered by this document, as shown in Table 1, is a variant of AS4716, the accepted gland standard for MS28775, O-ring packing seals. Piston diameters, gland internal diameters, groove sidewall angles and the surface finish are all defined by AS4716, but the gland outer retaining wall diameter is changed. AS4088 is similar to this document, but was developed by SAE A-6 for flight control and general-purpose cylinders. It differs from this document primarily by the clearance between the rod (piston) and outer gland wall. Since landing gears are more susceptible to dirt contamination, the additional clearance provides a larger path to allow excessive dirt accumulation to exit the gland.
Standard

Gland Design: Scraper, Landing Gear, Installation

2008-11-24
CURRENT
AS4052B
This SAE Aerospace Standard (AS) covers an alternate gland design for the installation of scraper/wiper rings in the lower end of landing gear shock struts for the purpose of contaminant exclusion. The defined scraper gland covered by this document, as shown in Table 1, is a variant of AS4716, the accepted gland standard for MS28775, O-ring packing seals. Piston rod diameters, gland internal diameters, groove sidewall angles and the surface finish are all defined by AS4716, but the gland outer retaining wall diameter is changed. The traditional scraper design installed into the glands detailed in Table 1 typically utilize components made from urethane or nitrile materials. These scraper designs, while still acceptable, must be reviewed in consideration to deicing, cleaners and disinfectant fluids applied to or in contact with the landing gear, as the materials of construction for the installed scrapers may not be compatible to these fluids.
Standard

Guide for Installation of Electrical Wire and Cable on Aircraft Landing Gear

1989-11-28
HISTORICAL
AIR4004
Recent field experience has indicated significant problems with some types of wire and cable as routed on aircraft landing gear. This Aerospace Information Report (AIR) is intended to identify environmental concerns the designer must consider, materials that appear to be most suitable for use in these areas, routing, clamping, and other protection techniques that are appropriate in these applications.
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