787Landing Gear Structure 起落架结构

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787Landing Gear Structure

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Proprietary
The information contained herein is proprietary to The Boeing
Company and shall not be reproduced or disclosed in whole or in
part or used for any reason except when such user possesses
direct, written authorization from The Boeing Company.
Dean Hefflinger
787 Services LCPT
Maintenance Operations
May 14, 2007
Landing Gear Structure
WARNING: The technology herein is controlled by the U.S. Export
Administration Regulations (EAR). Any export or re-export of this
document must comply with these regulations. Controlled by
ECCN: _9E991__
Boeing Proprietary COPYRIGHT © 2007 THE BOEING COMPANY
787 Landing Gear Structure
Boeing Proprietary COPYRIGHT © 2007 THE BOEING COMPANY
Landing Gear Structure
􀂄 Configuration & Materials Overview
􀂄 Design Improvements / Lessons Learned
􀂄 Finishes & HVOF
􀂄 Composite Braces
􀂄 Design Life & Overhaul Interval
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Landing Gear Structure
􀂄 Configuration & Materials Overview
􀂄 Optional – part-by-part comparison to previous models
􀂄 Design Improvements / Lessons Learned
􀂄 Finishes & HVOF
􀂄 Composite Braces
􀂄 Design Life & Overhaul Interval
􀂄 Optional – details of Boeing overhaul interval sampling
program
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Main Landing Gear
􀂄 Two Post, Four Wheel Main Gear
􀂄 Dual Brace Design
􀂄 Inboard Retracting
􀂄 Similar to 777 – Forward Trunnion supported at
the Rear Spar, Aft Trunnion supported at a
Gear Beam.
Nose Landing Gear
􀂄 Dual Wheel Nose Gear
􀂄 Forward Retracting
􀂄 Similar to 757, 767, 777
Conventional Boeing Configuration
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Landing Gear Loads Summary
1g Post Loads Comparison
787-8 486.0 / 370.0 62.8 222.1
767-400 451.0 / 350.0 47.4 211.8
777-200 547.0 / 460.0 62.7 255.7
Vmain (1g)
(kips)
Vnose (1g)
(kips)
Gross Weight
MTW / MLW (kips)
Model
􀂄 The 787 landing gear fits between the 767 and 777 in size
and load bearing capability
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
787-8 Main Landing Gear
Two post, four wheel main gear
􀂄 11.5 inch piston diameter
􀂄 22 inches available stroke
􀂄 Wheel base - 897 inches
􀂄 Main gear track - 386 inches
􀂄 Wheel spacing - 51 inches
􀂄 Axle spacing – 57.5 inches
Five primary support points:
􀂄 Forward trunnion
􀂄 Aft trunnion
􀂄 Drag brace upper spindle attachment
􀂄 Drag brace lock link attachment
􀂄 Side brace upper spindle attachment
L/H Gear
Looking Outbd
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Main Landing Gear – Materials
Miscellaneous
Ultra High Strength
Steel (300M)
Brace Spindles
Pins
Aluminum
Shock Strut Internals
Tow Fitting
Axles
Ultra High Strength
Steel (300M)
Inner Cylinder
High Strength
Titanium
Drag and Side
Braces
Composite
Torsion Links
High Strength
Titanium
Brake Rods
High Strength
Titanium
Truck Beam
High Strength
Titanium
Outer Cylinder
Ultra High Strength
Steel (300M)
Extensive use of
corrosion resistant
materials
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
787 Nose Landing Gear
Dual wheel nose gear
􀂄 7.5 inch piston diameter
􀂄 20 inches available stroke
􀂄 Wheel spacing – 29.5 inches
Four primary support points:
􀂄 Drag brace trunnions
􀂄 Outer cylinder trunnions
Steering
􀂄 Accomplished by two push-pull
actuators attached to the outer
cylinder by the steering plates.
􀂄 +/- 70 degrees steering available
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Nose Landing Gear - Materials
Torsion Links
High Strength
Titanium
Upper Drag
Brace
Aluminum
Lower Drag Brace
High Strength
Titanium
Steering Plates
High Strength
Titanium
Miscellaneous
Ultra High Strength
Steel (300M)
Pins
Aluminum
Shock Strut Internals
Lock Links
Tow Fitting
Inner and Outer
Cylinders
Ultra High Strength
Steel (300M)
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Optional Details
Details of MLG and NLG part comparisons to previous
models are available (17 hidden slides).
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Boeing & Messier-Dowty
Collaboration
􀂄 Boeing and Messier-Dowty are working together to ensure the
design and manufacturing experience of both companies is
understood and incorporated in the 787 landing gear design
􀂄 Establishment of the local Messier-Dowty office (Kent, Wa.)
allows for ease of communication
􀂄 Co-location of the Boeing and Messier-Dowty design
engineers during joint definition phase
􀂄 “Best Practices” reviews by Boeing and Messier-Dowty
􀂄 Weekly design reviews between Boeing and Messier-Dowty
(ongoing)
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Boeing & Messier-Dowty
Collaboration
􀂄 In the past Boeing identified the corrosion protection
requirements by utilizing design guides developed from lessons
learned and placing them on drawings
􀂄 While the 787 detailed design is being performed by Messier-
Dowty, they are still expected to meet the Boeing requirements
for the design of the structure, including corrosion protection as
defined in “Book 4” (part of the Requirements Package given to
M-D)
􀂄 Messier-Dowty materials, processes, finishes, etc. used on the
787 are being reviewed by Boeing (Standards Management
Board) to ensure that they meet our requirements.
􀂄 Boeing believes the incorporation of these requirements and
lessons learned will help assure that the 787 landing gear will
have performance similar to the rest of our fleet.
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 Increased use of titanium
􀂄 MLG – truck beam, inner cylinder, torsion
links, brake rods
􀂄 NLG – drag brace, torsion links, steering
components
􀂄 Increased use of corrosion resistant steel
􀂄 Selected main and nose landing gear pins
􀂄 Use of composites
􀂄 Main landing gear side and drag braces
􀂄 Increased use of corrosion inhibiting
compounds
􀂄 Threads, splines and selected bushing
installations
Design Improvements /
Lessons Learned
Improved Corrosion
Resistance
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 Reduced likelihood for heat damage (ladder
cracking)
􀂄 Incorporated 777 style shock strut
bearings (DU liners)
􀂄 Titanium MLG inner cylinder
􀂄 Use of WC-Co-Cr coating on inner
cylinder (applied by HVOF)
􀂄 Increased resistance to strut leakage
􀂄 Utilizing successful 777-style 3/8" cap
seal
Design Improvements /
Lessons Learned
Shock Strut
Improvements
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Cap Seal
􀂄 In older style Elastomer Contact Seals, the “rubber” element rides
directly against sliding chrome surface of inner cylinder
􀂄 In the newer “Cap Seal,” a secondary element rides against the
chrome, with an elastomer “energizer” to activate
Elastomer
Energizer
Teflon “Cap”
Backup Ring
􀂄 Excellent in-service
performance on 777
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 Reduced likelihood/susceptibility for heat
damage
􀂄 Joint optimization
􀂄 Increased bearing area
􀂄 Pivot pin “staked” to truck beam
􀂄 Improved materials
􀂄Custom 465 pivot pin
􀂄 Titanium truck beam and inner cylinder
􀂄 Inner cylinder - HVOF applied tungsten
carbide coating in bore
Design Improvements /
Lessons Learned
Improved MLG Pivot
Joint Geometry
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Inner Cylinder
Titanium
HVOF applied
tungsten carbide
coating in bore
“Staking” Pin
(no relative rotation
between truck beam and
pivot pin)
Pivot Pin
Custom 465
Truck Beam
Titanium
Pivot Pin
Custom 465 MLG truck pivot joint
bearing area increased
Truck Pivot Joint
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 Design for Environment Philosophy
􀂄 Minimized use of hexavalent chrome and
cad plating
􀂄 767 Wheel Spacers
􀂄 Extended brake sleeve configuration -
eliminating need for wheel spacer
􀂄 MLG Junction Box Migration
􀂄 Junction boxes mounted via brackets to
lugs on truck beam
􀂄 PDA (Parts Departing Aircraft)
􀂄 Additional retention means (e.g. spring
end fittings) incorporated in the design
to reduce the likelihood of PDA
787 Landing Gear - Part Comparisons
Additional
Improvements /
Lessons Learned
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Design Improvements /
Lessons Learned
􀂄 Junction box under
truck beam is hard
mounted via brackets to
lugs on truck beam
(eliminates band
clamps)
􀂄 (Wire harness is not
affected by change of
brake suppliers)
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Finish Schemes & HVOF
Finish Schemes
􀂄 Finish schemes will be similar to past Boeing landing gear with updates
to account for environmental requirements.
Wear Surfaces (inner cylinder, pin surfaces, etc.)
􀂄 Where practical, chrome plate is replaced with high performance
thermal spray coatings (e.g. tungsten-carbide based) on the wear
surfaces of the landing gear.
High Velocity Oxygen Fuel (HVOF) Coatings
􀂄 Improved wear performance
􀂄 Improved fatigue performance
􀂄 Improved corrosion protection of steel substrates
􀂄 Improved overhaul flow time for large parts
􀂄 Successfully introduced on 767-400ER
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
HVOF - Information
Thermal Spray Process
Feedstock
Powder, Wire or Rod
Energy Source
Thermal energy/heat
‘Molten’
Accelerated
Particle
Kinetic energy
Particle Splat
Splat Build-up
into a Coating
Substrate
􀂄Thermal Spray Process
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
HVOF – Corrosion Protection
Corrosion Protection
􀂄 Chrome plating contains numerous micro cracks that can link together and
traverse through the thickness of the plating. When this happens, a path is
created for moisture to reach the substrate, which will lead to corrosion
􀂄 Thermal spray coatings are applied as overlapping layers, with the final
structure being free from internal micro cracks.
􀂄 Repeated loading of HVOF coated parts can induce coating cracks;
however, these cracks typically do not reach the coating/substrate
interface. Cracks stop at the first or second deposited layer and travel
parallel to the substrate interface.
− This behavior results in an intact layer of HVOF coating that continues
to protect the steel base metal.
􀂄 Long term corrosion testing of HVOF coupons after fatigue testing has
demonstrated significantly improved corrosion resistance compared to Cr
plating
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
HVOF – Corrosion Protection
􀂄Chrome plating more susceptible to cracking than HVOF
coatings
HVOF
(pre-finished)
Chrome
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
HVOF – Corrosion Protection
Salt Spray Testing Results
􀂄 Boeing Cd-Ti Plating: 500 hours minimum with no base metal attack
􀂄 Boeing Cd-Ti + 1 coat primer: 2500 hours minimum with no base metal
attack
􀂄 Chrome plating: No requirement, but lab testing shows evidence base
metal corrosion 4 – 96 hours
􀂄 Boeing BMS 10-67 Type 17 HVOF: testing stopped after nine months
with no evidence of base metal attack
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
HVOF – Corrosion Protection
9 Month Salt Spray Exposure – Type 17
Salt Spray Test Results
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Side and Drag Braces
􀂄 The 787 is introducing
composite braces for
weight savings
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Braces
Drag Brace
Side Brace
LDB UDB
USB LSB
61
15
27
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 The bushings will be installed in a permanent (Ti) sleeve
􀂄 The permanent sleeve will be installed using adhesive and a
traditional thermal-fit installation method
􀂄 A traditional thermal-fit installation method has also been
selected to install the bushings in the permanent sleeve
􀂄 Instructions for overhaul will be provided in CMM with reference
to applicable Boeing SOPM
Composite Brace Bushing Installation
Composite lug
Permanent sleeve
(Ti)
Standard Al-Ni-
Bronze bushings
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
􀂄 Only the bushings are scheduled to be removed and replaced
during overhaul. (The permanent sleeve will not have to be
removed or replaced.)
􀂄 Inner diameter of the permanent sleeve will include a rework
allowance for repair/overhaul
􀂄 In the unlikely event the permanent sleeve needs to be replaced,
a rework allowance is also included in the composite brace lug
Composite Braces Rework Allowances
Additional Allowance in
Composite Lug (if needed)
Primary Allowance in
Ti Sleeve
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Braces Bushing Installation
􀂄Bushing Components
Inner Sleeve
Al-Ni-Br bushings
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Braces Bushing Installation
􀂄 Titanium sleeve and one Al-Ni-Br bushing
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Brace Bushing Installation
􀂄 Completed Demonstrator Part
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Composite Braces Lubrication Fittings
Drag Brace Apex
shown (typical)
􀂄 No lube fittings in composite structure
􀂄 Lubrication through pins / metal structure only
􀂄 BMS 3-33 grease (Std. for most of landing gear)
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Design Life
Safe-Life Limited Structure
􀂄 The landing gear is designed for a safe-life limit
commensurate with the airframe structure Design Service
Objective (DSO)
􀂄 787-3 - 55,000 cycles
􀂄 787-8 - 44,000 cycles
􀂄 787-9 - 44,000 cycles
􀂄 The composite braces will not be life-limited
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Overhaul Interval - Plan
􀂄 FAA, ISC and Boeing have reached agreement on a conditional
plan for 12 yr / 24,000 FC LG overhaul interval (Feb ‘07 ISC Mtg.)
􀂄 Plan will involve Boeing working with a select number of
airlines to accomplish a limited sampling program.
􀂄 Operators not part of the program do not need to
accomplish the sampling inspections/restorations.
􀂄 Intent is to validate the design / corrosion protection schemes
are working as designed
􀂄 Finalization of the 12 yr / 24,000 cycle LG overhaul in MRB
Report will be contingent upon normal findings from the
inspections
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Overhaul Interval – Documentation &
Reporting
􀂄 Details of sampling program will be added to the 787 MSG-3 ISC
Policy & Procedures Handbook, and will be referenced in the
FAA MRB Report
􀂄 The FAA and Boeing recognize that normal/routine findings
may occur. Reduction of overhaul interval would be necessary
in the event of “significant” corrosion or wear findings.
􀂄 Definition of “significant” findings will be established prior
to implementation
􀂄 Results of all inspections will be reported to the ISC/FAA
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Optional Details
Details of sampling program are available
(11 hidden slides).
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
LG - Work Breakdown by Sites
Seattle
MLG & NLG
Final
Assembly
(Initial
Production)
MLG Test
MLG Truck
Assembly
& Truck
Beam
Messier-Dowty
Gloucester
England
NLG
Outer Cylinders
MLG
Outer Cylinders
Messier-Dowty
Montreal
Canada
NLG
Inner Cylinders
MLG
Inner Cylinders
Messier-Dowty
Bidos
France
Brake Rods
Messier-Dowty
Suzhou
China
Messier-Dowty
Kent / Evt
USA
MLG & NLG
Final
Assembly
(2009+)
LCPT Team
Boeing
Everett
USA
MLG
Installation
Boeing
Wichita
USA
NLG
Installation
NLG Test
Messier-Dowty
Toronto
Canada
NLG Test
COPYRIGHT © 2007 THE BOEING COMPANY Boeing Proprietary
Landing Gear Structure
􀂄 Parts are on their way!

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787Landing Gear Structure 起落架结构

zhangdamu

787Landing Gear Structure 起落架结构