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University of Applied Sciences Amsterdam Aviation Studies

List of appendices

Analysis of the landing gear

Group 2A2I:

Tom Boeschoten

Anouk Elsendoorn

Mike de Jong

Vito Kluis

Thijs Kuijs

Ben van Lent

Jeroen Mulder

Bert van Woensel Amsterdam, October 15th 2009

University of applied sciences Amsterdam Project Team 2A2I

Appendix list

Appendix I Project Assignment ................................................................ 1

Appendix II Pyramid model ........................................................................ 2

Appendix III Project Group Agreements .................................................... 3

Appendix IV Air ground logic system ......................................................... 5

Appendix V Brake system .......................................................................... 6

Appendix VI Anti-skid/auto brake system .................................................. 7

Appendix VII Anti-skid transducer ............................................................... 8

Appendix VIII Nose wheel steering ............................................................... 9

Appendix IX Landing gear control panel .................................................. 10

Appendix X Selector/bypass solenoid operated valve ........................... 11

Appendix XI Truck dimensions ................................................................. 12

Appendix XII Radii taxi turns ...................................................................... 13

Appendix XIII VLS’ forces on main landing gear ....................................... 14

Appendix XIV VLS force on torque link ...................................................... 15

Appendix XV Friction force calculation ..................................................... 16

Appendix XVI MEL 32-53-01 Main Gear Steering System .......................... 18

Appendix XVII Fault Isolation Manual, task 53-22-00-810-813 ................... 20

Appendix XVIII Fault Isolation Manual, task 53-22-00-810-810 ................... 21

Appendix XIX AMM task 32-53-03-000-801/32-53-03-400-801 .................... 22

Appendix XX AMM 32-45-04-700-801 .......................................................... 28

Appendix XXI Process report ...................................................................... 33

Appendix XXII List of abbreviations ............................................................. 35

University of Applied Sciences Amsterdam Project Team 2A2I

1

Appendix I Project Assignment


2

Landing gear

H1. Analysis of

the landing gear

1.1 Introduction

landing gear

B777

1.1.1 Purpose

1.1.2 Lay-out

1.2 Materials

1.2.1 Steel

1.2.2 Aluminum

1.2.3 Titanium

1.2.4 Carbon

1.3 Structural

shock absorbing

1.3.1 Shock strut

and torque link

1.3.2 side braces

and locks

1.3.3 Air ground

logic

1.4 Deceleration

1.4.1Brakes

1.4.2 Auto

brakes

1.4.3 Anti-skid

1.4.4 Brake

temp

1.5 Taxiing

1.5.1 Nose

wheel steering

1.5.2 Main

wheel steering

1.5.3 Wheels

1.6 Retraction

and extension

1.6.1 Retraction

1.6.2 Extension

1.7 Regulations

1.7.1 CS-25

1.7.2 Minimum

Equipment List

H2. Forces on

the landing gear

2.1 Dimensions

and weight

2.2 Forces

during taxi turn

2.3 Forces on

the tires during

landing

2.3.1 Calm

2.3.2 Cross wind

H3. Possible

failures on the

landing gear

3.1 Main gear

steering

3.1.1 Cause

3.1.2

Consequense

3.1.3

Maintenance

3.1.4 Costs

3.2 Wheel

failure

3.1.1 Cause

3.1.2

Consequense

3.1.3

Maintenance

3.1.4 Costs

3.3 Conclusion

Appendix II Pyramid model

This pyramid model is made for the starting document and is the basis for the report.


3

Appendix III Project Group Agreements

During the preparation- and implementation phase there will be group meeting to determine which direction to go. It’s important to line up rules, considering these meetings (1). During the meetings every minute is taken according to certain rules composed in advance (2). These writings need to be published on the BSCW page, following rules, so that every group member can read them over when-ever they like (3). Finally some rules need to be composed, considering the circumstances in which a group member shows up to late, not at al or doesn’t make the deadlines (4).

1. Group meetings

The group meetings are the most important gatherings of the group. To make sure these meetings pass through

properly, they have to content to seven rules:

• The chairman is always in charge and makes sure that everyone has the chance to speak

• The chairman prepares every meeting, so that weakly messages, items on the agenda, an-nouncements and the planning can be presented to the group

• The secretary minutes as fully as possible every statement, question, answer, points of action and decisions during the meeting

• The secretary is positioned next to the chairman, so that the chairman can check whether every-thing is minute right

• The chairman mails the time and place to meet. If possible he can arrange a place where they can meet, for example a project room or a classroom.

• If a group member is prevented to come to the meeting he / she has to check out by phone. This can also be by mail, but then before nine o’clock the evening before, so that the chairman can take this into account for the meeting. After this time it can only be managed by telephone.

2. Minutes

The minutes are an aid in which every agreement and event within or without the group are mentioned. These

minutes need to content to seven guidelines:

• The minutes have to conclude to the Lay- out guidelines

• The minutes need to be worked out, as completely as possible

• A chronologic arrangement need to be found in the minutes

• Everything that is discussed need to be mentioned in the minutes! For example a question and answer with the initials of the concerned member that spoke

• At the end of the minutes a action- and decision- list is added

• The minutes need to be processed as quickly as possible after the meeting. Preferably the same night, if that’s not possible before six o’clock the next night

• After nine o’clock in the evening every group member needs to check his mail once All these arrangement will apply from week three, because these rules are noted down in week two.

3. BSCW

It’s necessary to make guidelines concerning the use of BSCW. The prevent chaos on this page it has to content

to four rules:

• One group member will be responsible for the arrangements of the documents at BSCW. It has the be clearly arranged and in an classification per chapter and paragraph

The documents are placed on BSCW with the following guideline example: 1.3.1 Hydraulics

• so ( paragraph number and filename )

• When a merged file is altered, it’s important to delete the previous file first and place the new doc-ument afterwards. This to prevent double versions on the document at hand.

• Documents that are not relevant need to be deleted form BSCW All these arrangement will apply from week three, because these rules are noted down in week two.


4

4. Disavow and consequences

There are three ways of disavow: showing up late, not at all or doesn’t make deadlines. Every cir-cumstance listens to certain rules which are mentioned in this chapter. When a member shows up more then ten minutes late the following rules apply:

• The second time a member is too late a warning is given by the chairman

• The fourth time, a meeting is arranged between the person in question and the chairman, in which the chairman represents the opinion of the group. This means that the group has to come to a de-cision / opinion first during a quick gathering. The responsible teacher has to be noticed by the chairman.

• The sixed time a meeting about the matter is arranged with de person at hand. After the meeting the group will discuss what to do, which probably will lead to an exit of the person. This is only possible if the decision is unanimously taken, if this not the case agreements have to made about the following procedure.

• The eight time means exposal which is not discussible. When a member doesn’t make the deadline, the following rules apply

• The second time a conversation is organized with the chairman

• The fourth time the person receives a official warning from the group

• The sixed time a meeting about the matter is arranged with de person at hand. After the meeting the group will discuss what to do, which probably will lead to an exit of the person. This is only possible if the decision is unanimously taken.

When a member doesn’t show up without notifying the group, the following rules apply:

• The first time this happens, the person receives an official warning, and the responsible teacher will be notified

• The second time the person is thrown out of the group. The rules previous rules about the subject apply in this case. This looks a little harsh, but the group sees this as a serious offence.

Sometimes there are grounding reasons in which the person commits an offence. If the group is un-animous about the grounding of the rule, it can be remembered when a person reaches the critical level of a near exposal.


5

Appendix IV Air ground logic system

The air ground logic with different components are shown.


6

Appendix V Brake system

In this figure a brake system with its components is shown.

2

1

3

4

5

6

7

8

9

10

1. Rotor 2. Stator 3. Axle bushing 4. Axle sleeve 5. Conical backing plate 6. Pressure plate 7. Self-adjusting piston 8. Attachment point 9. Center brake attachment point 10. Brake rod


7

Appendix VI Anti-skid/auto brake system

In this figure the anti-skid/auto brake system with the different components is shown.


8

Appendix VII Anti-skid transducer

In this figure the anti-skid transducer is shown and how installed in the axle.

1. Anti-skid transducer 2. Support

1

2


9

Appendix VIII Nose wheel steering

The nose wheel steering system makes the aircraft movable on the ground.

1

2

3

4

5

6

7

8

9

10

1. Tiller/gearbox 2. Drum mechanism 3. Upper cable loop 4. Centering and rudder interconnect mechanism 5. Broken cable compensation 6. Pivot link 7. Centering mechanism 8. Lower cable loop 9. Summing mechanism 10. Metering valve module 11. Actuators 12. Steering collar 13. Torque link

11 12

13


10

Appendix IX Landing gear control panel

By moving the landing gear lever, the landing gear can be extended and retracted.

1

2

3

1. Landing gear lever

2. Lever lock override switch

3. Alternate gear switch


11

Appendix X Selector/bypass solenoid operated valve

This appendix shows the operation of the solenoid valves, as well as the operation of the three-way valve, within the selector/bypass valve. In this figure, the down configuration has been selected; the landing gear is extended.

1. Down solenoid 2. Up solenoid 3. Three-way valve

The landing gear lever is in the down position, meaning the down solenoid is powered (1). The up solenoid is connected to the ground (2). The down solenoid ensures the three way valve is in its cur-rent position (3).

2

1

3


12

Appendix XI Truck dimensions

In this appendix the dimensions of the main landing gear truck are displayed.

A

A

A

A

B

B

C

D

A= 0,735 m B= 1,55 m C= 2,325 m D= 3,10 m


13

Appendix XII Radii taxi turns

In this appendix the turn dimensions are shown.


14

Appendix XIII VLS’ forces on main landing gear

This figure shows the lay-out of the main landing gear, with the direction of movement indicated with the red arrow, α indicating the angle of movement over the asphalt, the radii of the turn circle for the front and aft wheels and the points A and B where all the forces are working from. Point A is the centre point of the four front wheels, point B the centre point of the two aft wheels. The three forces in point A can be separated as follows:

The same can be done for the forces in point B:

Fw, x

Fw, y Fw

A

Fc, y

Fc, x

Fc

A

Frf, x

Frf Frf, y

A

B

A Rfront

Raft

Frf

B

Frf,x

Frf,y

Fw, x

Fw

B

Fw, y

Fc, x

Fc, y Fc

B

α


15

Appendix XIV VLS force on torque link

A top view of the torque link can be seen as a vertical line, with the force working on the hinge of the torque link.

0,63m

Ftorque link


16

Appendix XV Friction force calculation

To calculate the resulting friction, the rolling friction and dynamic surface friction must be calculated. On each wheel of the landing gear a rolling friction is working, Fwr, the second friction is the dynamic friction, Fwd. This forces can be rewritten to on resulting force Fr. Because of the weight which is distri-buted over the six wheels, every wheel undertakes the same amount of friction.


17

Because of the similar forces and symmetrical landing gear, no mo-mentum is created around the shock strut. This means, the two friction force can be written as one force , acting at the end of the shock strut. The total force on one MLG has to be used in the friction equations. The rolling friction can be calculated using formula 1.

�� = 0,035 × .� �.��,� ,�� = 99418,39�

The dynamic friction can be calculated using formula 3 �� = 1803733,6 × 0,67 = 1208501,5� The resulting force can be calculated using the cosine law: �� = �� + �� − 2 × � × � × cos $

�� = ��

� + �� − 2 × �� × �� × cos $

$ = 180° − 18,4° = 161,6° �� = &201416,9� + 16600� − 2 × 201416,9 × 16600 × cos 161,6 ='()(*(+

The angle in which the resulting force acts can be determined using the sine law:

,-./∝ = 1

-./ 2 = 3-./ 4

�� -./∝ = ��

-./ �,�

∝= sin8 9�� ×-./ �,�� : = (, ;°


18

Appendix XVI MEL 32-53-01, Main Gear Steering System

May be inoperative provided:

a. Main gear steering actuators are verified locked in the center position. b. Main gear steering system is deactivated.

PLACARD None

MAINTENANCE (M) Verify that both main gear steering actuators are locked in the center position and deactivate the main gear steer-ing system (AMM 32-00-00/901). 1. Verify left and right main gear steering Power Control Actuators (PCA) are locked in the centered position.

A. Look through the lock indication window on each PCA and if you cannot see the metal pin on the PCA, the PCA is locked. B. If you can see the metal pin on either PCA, it is not locked. Use the Push Back method (preferred) or the Check Valve Bleeding method to move the unlocked PCA into the locked position.

1) Push Back Method:

a. Connect a tow vehicle to the nose landing gear or forward tow fitting on the affected main landing gear (AMM 09-11-00/201). b. Move the towing lever, on the forward side of the nose landing gear, to the TOW position. c. Release the parking brake. d. Move the manual shutoff valve handle on the unlocked PCA to the OFF position to isolate the PCA. e. Remove all chocks from around the nose landing gear tires and the main landing gear tires. f. Put a chock behind the aft axle tire that is nearest the unlocked PCA (wheel #10 on the left gear, wheel #12 on the right gear).

NOTE: Do not put a chock behind the other aft axle tire (wheel #9 on the left gear, wheel #11 on the right gear).

g. Use the tow vehicle to slowly push the airplane rearwards onto the chock. Stop airplane movement if the airplane tire moves onto the chock, the PCA locks, or the chock moves. h. Look through the lock indication window on the PCA and if you can not see the metal pin on a PCA, the PCA is locked. i. If a PCA remains unlocked, place a chock behind the aft axle tire that is farthest from the unlocked PCA, but on the same truck (wheel #9 on the left gear, wheel #11 on the right gear).

NOTE: Do not place a chock behind the other aft axle tire (wheel #10 on the left gear, wheel #12 on the right gear).

j. Use the tow vehicle to slowly push the airplane rearwards onto the chock. Stop airplane movement if the airplane tire moves onto the chock, the PCA locks, or the chock moves. k. Look through the lock indication window on the PCA and if you can not see the metal pin on the PCA, the PCA is locked.

2) Check Valve Bleeding Method:

NOTE: This method loosens the check valve on the unlocked PCA. If you do this, you may void the warranty with the supplier Parker/Abex/NWL. It is recommended that this method be used only after you have tried the Push Back Method. Use caution. The hy-draulic fluid trapped in the PCA is under pressure, even when the center hydraulic sys-tem is depressurized.


19

a. Make sure the parking brake is set. b. Lift the aft axle of the main landing gear with the unlocked PCA until the aft tires do not touch the ground (AMM 07-11-03/201).

NOTE: Make sure you use the jack pad that is part of the pivot pin for the aft axle.

c. Depressurize the center hydraulic system including the reservoir (AMM 29-11-00/201). d. Move the manual shutoff valve handle on the unlocked PCA to the OFF position to isolate the PCA. e. Use cleaner, TEC 86-2 (or equivalent) to clean the area around the check valve (anti-cavitation check valve) on the unlocked PCA. f. Remove the sealant and the lockwire from the check valve on the unlocked PCA. g. Put a rag around the unlocked PCA valve to catch the leak of fluid from the valve. h. Slowly turn the check valve 1 to 2 turns counter-clockwise until hydraulic fluid starts to leak from under the head of the check valve.

NOTE: Do not remove the check valve from the PCA.

i. Wait until the hydraulic fluid does not leak from under the check valve. j. Push on the right aft tire (wheel #10 on the left gear, wheel #12 on the right gear) in the forward direc-tion to apply a compressive force on the unlocked PCA. You can use a lever between tires #5 and #9 on the left gear and #7 and #11 on the right gear to help apply the force on the PCA.

NOTE: It may be necessary to apply the force for 30 to 60 seconds. Hydraulic fluid may leak from under the head of the check valve when you apply the force.

k. Look through the lock indication window on the PCA and if you can not see the metal pin on the PCA, the PCA is locked. l. If the PCA is not locked, wait approximately 5 minutes and then reapply the force. m. Look through the lock indication window on the PCA and if you can not see the metal pin on the PCA, the PCA is locked. n. Tighten the check valve to 175-200 pound-inches. o. Move the manual shutoff valve handle on the PCA to the STEER position to activate the PCA. p. Pressurize the center hydraulic system (AMM 29-11-00/201). q. Ensure there is no hydraulic leakage from under the head of the check valve. If the check valve leaks, replace the seals on the check valve. r. Lower the aft axle and remove the jack. s. Install lockwire on the check valve. t. Apply sealant, MIL-A-46146 around the interface between the check valve and the PCA manifold and allow to cure.

NOTE: Application of sealant may be temporarily deferred.

2. Deactivate the main gear steering system.

A. Shutoff hydraulic power to both PCAs. 1) Pull the ball-lock pin, on the handle for the manual shutoff valve, aft. 2) Move the handle for the manual shutoff valve to the OFF position. 3) Release the ball-lock pin to hold the handle in the OFF position.

B. Open and red clip P110 panel LG MAIN GEAR STEERING circuit breaker.

NOTE: Removing power from the Main Gear Steering Control Unit (MGSCU) will re-place correlated maintenance messages with correlation to maintenance message 32-68840.

OPERATIONS NOTE There is little or no change in U-turn widths if the Flight Crew Operations Manual Minimum Radius Turn procedure is used. Minimum radius turns will result in the following effects:

• Substantially increased tire scuffing.

• Increased thrust required for the turn.

• Somewhat rougher cabin ride, particularly in the area above the main gear.

• Increased risk of damage to Main Landing Gear Hydraulic Line Forward Support Link Assembly.


20

Appendix XVII Fault Isolation Manual, task 53-22-00-810-813

EICAS Message - Main Gear Steering (EICAS STATUS) (1) If the status EICAS message "MAIN GEAR STEERING" occurs intermittently without a corre-lated maintenance message, and is not present at the time of dispatch, then there is no mainten-ance action required.

(a) This fault does not present a safety concern, the airplane can be dispatched without troubleshooting. (b) To isolate the fault it is recommended that the airplane be dispatched with both left and right PCA manual shutoff levers in the "STEER" position until you can troubleshoot the PCA manual shutoff switch indication.

(2) Reference data: (a) 777-MT-32-013

Fault Isolation Procedure (1) Find the power control actuator that is causing the problem:

(a) Make sure the two shutoff levers are in the "STEER" position. (b) Use the landing gear BRKS/STRNG EICAS maintenance page to find the power con-trol actuator (PCA) that is causing the problem.

NOTE: The faulty PCA will cause the main gear steering item on the BRKS/STRNG page to display "DISABLED".

(2) Do one of these tasks:: (a) Do this task: MG Steering Power Control Actuator (Right) Problems - Fault Isolation, 32-53 TASK 810. (b) Do this task: MG Steering Power Control Actuator (Left) Problems - Fault Isolation,

32-53 TASK 805.


21

Appendix XVIII Fault Isolation Manual, Task 53-22-00-810-810

MG Steering Power Control Actuator (Right) Problems - Fault Isolation A. Maintenance Messages

(1) This task is for maintenance message: 32-63020. B. Initial Evaluation

(1) If the MAT shows ACTIVE for the maintenance message, then do the Fault Isolation procedure below. (2) If the MAT shows LATCHED for the maintenance message, then do these steps:

NOTE: You can use the landing gear BRKS/STRNG MAINTENANCE page to view the steered angles.

(a) Do this task: Nose Landing Gear Torsion Link Disconnection/Electrical Har-

ness Storage, AMM TASK 32-21-11-000-803. NOTE: This is done to prevent scrubbing of the tires on the nose landing gear and to prevent any side motion of the airplane.

(b) For the center hydraulic system, do this task: Main Hydraulic System Pressuri-zation, AMM TASK 29-11-00-860-801. (c) Turn the steering tiller fully counterclockwise. (d) Wait approximately 5 seconds. (e) Release the steering tiller.

NOTE: The steering tiller will go back to the neutral position.

(f) Turn the steering tiller clockwise. (g) Wait approximately 5 seconds. (h) Release the steering tiller.

NOTE: The steering tiller will go back to the neutral position.

(i) If the MAT shows ACTIVE or LATCHED for the maintenance message, then do the Fault Isolation Procedure below. (j) If the MAT shows NOT ACTIVE for the maintenance message, then there was an intermittent fault. Do these steps to complete the task:

1) For the center hydraulic system, do this task: Main Hydraulic System Power Removal, AMM TASK 29-11-00-860-808. 2) Do this task: Nose Landing Gear Torsion Link Connection, AMM TASK 32-21-11-400-803.

C. Fault Isolation Procedure

(1) Replace the right main gear steering/locking power control actuator, M32263. These are the tasks:

Main Landing Gear Steering/Locking Power Control Actuator Removal, AMM TASK 32-53-03-000-801, Main Landing Gear Steering/Locking Power Control Actuator Installation, AMM TASK 32-53-03-400-801.


22

Appendix XIX Aircraft Maintenance Manual task, 32-53-03-000-801/32-53-03-400-801

Main Landing Gear Steering/Locking Power Control Actuator Removal (1) For the center hydraulic system, do this task: Main Hydraulic System and the Re-servoir Depressurization, TASK 29-11-00-860-807 . SUBTASK 32-53-03-040-001 (2) Move the towing lever, on the forward side of the nose landing gear, to the TOW position.

NOTE: This isolates the steering system for the nose landing gear from hydraulic power and prevents input to the main gear steering.

SUBTASK 32-53-03-040-002 (3) Install the SPL-1499 NLG towing lever pin, through the towing lever.

NOTE: You use the NLG Towing Lever Lock Pin to hold the tow-ing lever in the TOW position.

SUBTASK 32-53-03-860-008 (4) Open this access panel: 117AL Main Equipment Center Access Door SUBTASK 32-53-03-860-001

(5) Open this circuit breaker and install safety tag: Left Power Management Panel, P110

• N 27 C32619 LG MAIN GEAR STEERING SUBTASK 32-53-03-480-006

WARNING: MAKE SURE THE DOWNLOCK PINS ARE IN-STALLED IN ALL THE LANDING GEAR. WITHOUT THE DOWNLOCK PINS, THE LANDING GEAR COULD RETRACT AND CAUSE INJURIES TO PERSONS AND DAMAGE TO EQUIPMENT.

(6) If the downlock pins are not installed in the nose and main landing gear, do this task: Landing Gear Downlock Pins Installation, TASK 32-00-30-480-801. SUBTASK 32-53-03-860-009 (7) Install chocks around the forward or center tires of the main landing gear.

NOTE: Do not install the chocks around the aft tires. The aft axle will turn during the test.

Main Landing Gear Steering/Locking Power Control Actuator Removal SUBTASK 32-53-03-020-007 (1) Do these steps to remove the bracket [22]:

(a) Remove the screw [21] and clamp [20]. (b) Remove the nut [19], washer [18] and bolt [17].


23

SUBTASK 32-53-03-020-001 (2) Disconnect the electrical connector [2]. SUBTASK 32-53-03-020-002

WARNING: LOOSEN FITTINGS SLOWLY AND CONTI-NUOUSLY TO RELEASE REMAINING PRESSURE IN THE HYDRAULIC LINES. HYDRAULIC FLUID UNDER PRESSURE CAN CAUSE INJURY TO PERSONS.

(3) Disconnect the hydraulic lines [4] and [7]. SUBTASK 32-53-03-480-001 (4) Install caps or plugs on the hydraulic lines [4] and [7]. SUBTASK 32-53-03-480-002 (5) Put the SPL-1852 MLG actuator sling, around the actuator [3]. SUBTASK 32-53-03-480-003 (6) Connect the SPL-1852 AMM Manual for 777-200 AMM (Rev. 43) 32-53-03-000-801 Page No. 2031 This page should not be retained for reference Created on: 24-2-2005 MLG actuator sling, to the SPL-1556 400 pound maximum capacity boom hoist. SUBTASK 32-53-03-020-003 (7) Do these steps to remove the retention pin [1] which holds the actuator [3] to the aft axle[16]:

(a) Remove the cotter pin [11], nut [12], washer [15], bolt [14], and collar [13]. (b) Remove the pin [1] which holds the actuator [3] to the aft axle [16].

1) If it is difficult to remove the pin [1], for the aft axle [16], do this task: Lift the Airplane with Axle Jacks, TASK 07-11-03-580-801.

SUBTASK 32-53-03-020-004 (8) Do these steps to remove the pin [1] which holds the actuator [3] to the steering crank [10]:

(a) Remove the cotter pin [11], nut [12], washer [15], bolt [14], and collar [13]. (b) Remove the pin [1] which holds the actuator [3] to the steering crank [10].

1) If it is difficult to remove the pin [1], for the aft axle [16], do this task: Lift the Airplane with Axle Jacks, TASK 07-11-03-580-801 .

SUBTASK 32-53-03-020-005 (9) Remove the actuator [3]. SUBTASK 32-53-03-480-004 (10) Put caps on the ports of the actuator [3]. Main Landing Gear Steering/Locking Power Control Actuator Installation SUBTASK 32-53-03-480-005 (1) For the aft axle [16], do this task: Lift the Airplane with Axle Jacks, TASK 07-11-03-580-801 to lift the airplane.

NOTE: Use the jack pad located beneath the aft axle pivot pin, not the pad attached to the aft axle.

SUBTASK 32-53-03-420-001 (2) Use the SPL-1852 MLG actuator sling , and the SPL-1556 400 pound maximum capacity boom hoist, to lower the actuator [3] into position over the landing gear truck. SUBTASK 32-53-03-420-002


24

(3) Do these steps to install the retention pin [1] which holds the actuator [3] to the steering crank [10]:

(a) Install the retention pin [1] to connect the actuator [3] and the steering crank [10].

1) If it is difficult to install the pin [1], for the aft axle [16], do this task: Lift the Airplane with Axle Jacks, TASK 07-11-03-580-801 .

(b) Install the collar [13], bolt [14], washer [15], nut [12], and cotter pin [11]. SUBTASK 32-53-03-420-006 (4) Do these steps to install the retention pin [1] which holds the actuator [3] to the aft axle [16]:

(a) Move the axle until you can install the retention pin [1]. 1) If it is difficult to install the retention pin [1], for the aft axle [16], do this task: Lift the Airplane with Axle Jacks, TASK 07-11-03-580-801.

(b) Install the retention pin [1] to connect the actuator [3] to the aft axle [16]. (c) Install the collar [13], bolt [14], washer [15], nut [12], and cotter pin [11].

SUBTASK 32-53-03-080-003 (5) Disconnect the SPL-1852 MLG actuator sling AMM Manual for 777-200 AMM (Rev. 43) 32-53-03-400-801 Page No. 2036 This page should not be retained for ref-erence Created on: 24-2-2005, from the SPL-1556 400 pound maximum capacity boom hoist. SUBTASK 32-53-03-080-004

(6) Remove the SPL-1852 MLG actuator sling . SUBTASK 32-53-03-480-007 (7) If you lifted the aft axle with a jack, lower the aft axle [16]. SUBTASK 32-53-03-480-008 (8) Remove the jack from under the aft axle [16]. SUBTASK 32-53-03-080-001 (9) Remove the caps or plugs from the hydraulic lines [4] and [7]. SUBTASK 32-53-03-420-003 (10) Connect the hydraulic lines [4] and [7]. SUBTASK 32-53-03-420-007 (11) Connect the electrical connector [2]. SUBTASK 32-53-03-020-008 (12) Do these steps to install the bracket [22]:

(a) Install the bolt [17], washer [18] and nut [19] to connect the bracket [22] to the actuator [3]. (b) Install the clamp [20] and screw [21] on the bracket [22].

SUBTASK 32-53-03-860-002 (13) Remove the safety tag and close this circuit breaker: Left Power Management Panel, P110 Row Col Number Name N 27 C32619 LG MAIN GEAR STEERING SUBTASK 32-53-03-860-010 (14) Close this access panel: Number Name/Location 117AL Main Equipment Center Access Door SUBTASK 32-53-03-860-011 (15) Remove the SPL-1499 NLG towing lever pin, from the towing lever. SUBTASK 32-53-03-020-006 (16) Do this task: Nose Landing Gear Torsion Link Disconnection/Electrical Harness Storage, TASK 32-21-11-000-803. SUBTASK 32-53-03-860-006


25

(17) Do this task: Supply Electrical Power, TASK 24-22-00-860-805. AMM Manual for 777-200 AMM (Rev. 43) 32-53-03-400-801 Page No. 2037 This page should not be retained for reference Created on: 24-2-2005 SUBTASK 32-53-03-860-007

WARNING: KEEP PERSONS AND EQUIPMENT CLEAR OF THE FLIGHT CONTROL SURFACES, THE THRUST REVERS-ERS, AND THE LANDING GEAR. THESE COMPONENTS CAN MOVE SUDDENLY WHEN YOU SUPPLY HYDRAULIC POW-ER. THIS CAN CAUSE INJURIES TO PERSONS AND DAM-AGE TO EQUIPMENT.

(18)

CAUTION: MAKE SURE THAT THE LANDING GEAR IS CLEAR OF PERSONS AND EQUIPMENT. IN THIS TEST, THE AFT AXLE WILL TURN. THIS CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT.

For the center hydraulic system, do this task: Main Hydraulic System Pressurization, TASK 29-11-00-860-801 . SUBTASK 32-53-03-710-002 (19) Do these steps 15 times to bleed the actuator [3]:

NOTE: During the first of the 15 cycles, the aft axles may not move. When the aft axles move during subsequent cycles, it can be determined as normal.

(a) Make sure the parking brake is released. (b) Rotate the Captain's tiller fully clockwise and hold for 5 seconds. (c) Make sure the left and right aft axles turn smoothly. (d) Release the Captain's tiller. (e) Make sure the left and right aft axles move back to the centered position smoothly. (f) Rotate the Captain's tiller fully counterclockwise and hold for 5 seconds. (g) Make sure the left and right aft axles turn smoothly. (h) Release the Captain's tiller. (i) Make sure the left and right aft axles move back to the centered position smoothly.

SUBTASK 32-53-03-790-001 (20) Make sure there is no leakage from the actuator [3] and hydraulic lines. SUBTASK 32-53-03-710-001 (21) Do these steps to do an installation test of the actuator [3]:

(a) Show the LANDING GEAR BRKS/STRNG maintenance page on the multi-function display (MFD) ( TASK 31-61-00-800-804 ).

NOTE: Use one of the control display units (CDUs) in the flight compartment to show the LANDING GEAR ACTN/INDN main-tenance page.


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(b) Make sure these indications show on the maintenance page: 1) The L TILLER and R TILLER angles are 1 °L - 1 °R. 2) The LEFT and RIGHT AFT AXLE angles are 0.5 °L - 0.5 °R. 3) The LEFT and RIGHT AFT AXLEs are LOCKED. 4) The LEFT and RIGHT AFT AXLEs are neither FAILED nor DIS-ABLED.

(c) Rotate the Captain's tiller clockwise until the L TILLER angle on the main-tenance page is 69 °R - 71 °R and hold it. (d) Make sure these indications show on the maintenance page:

1) The L TILLER and R TILLER angles are 69 °R - 71 °R. 2) The LEFT and RIGHT AFT AXLE angles are 7.5 °L - 8.5 °L. 3) The LEFT and RIGHT AFT AXLEs are UNLOCKED.

AMM Manual for 777-200 AMM (Rev. 43) 32-53-03-400-801 Page No. 2038 This page should not be retained for reference Created on: 24-2-2005

4) The LEFT and RIGHT AFT AXLEs are neither FAILED nor DIS-ABLED.

(e) Release the Captain's tiller. (f) Make sure these indications show on the maintenance page:

1) The L TILLER and R TILLER angles are 1 °L - 1 °R. 2) The LEFT and RIGHT AFT AXLE angles are 0.5 °L - 0.5 °R. 3) The LEFT and RIGHT AFT AXLEs are LOCKED. 4) The LEFT and RIGHT AFT AXLEs are neither FAILED nor DIS-ABLED.

(g) Rotate the Captain's tiller counter-clockwise until the L TILLER angle on the maintenance page is 69 °L - 71 °L and hold it. (h) Make sure these indications show on the maintenance page:

1) The L TILLER and R TILLER angles are 69 °L - 71 °L. 2) The LEFT and RIGHT AFT AXLE angles are 7.5 °R - 8.5 °R. 3) The LEFT and RIGHT AFT AXLE's are UNLOCKED. 4) The LEFT and RIGHT AFT AXLE's are neither FAILED nor DIS-ABLED.

(i) Release the Captain's tiller. (j) Make sure these indications show on the maintenance page:

1) The L TILLER and R TILLER angles are 1 °L - 1 °R. 2) The LEFT and RIGHT AFT AXLE angles are 0.5 °L - 0.5 °R. 3) The LEFT and RIGHT AFT AXLE's are LOCKED. 4) The LEFT and RIGHT AFT AXLE's are neither FAILED nor DIS-ABLED.

(k) After 30 seconds, make sure these EICAS messages are not shown on the EICAS.

1) MAIN GEAR STEERING (Advisory) 2) MAIN GEAR STEERING (Status)

(l) Look for the maintenance message on the Extended Maintenance, Existing Fault display (on the MAT). (m) Make sure no faults are ACTIVE in (32) Main Gear Steering System faults.

I. Put the Airplane Back to Its Usual Condition SUBTASK 32-53-03-860-004 (1) For the center hydraulic system, do this task: Main Hydraulic System Power Re-moval, TASK 29-11-00-860-808 . SUBTASK 32-53-03-640-002


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(2) Lubricate the main gear steering actuator at the grease fittings, do this task: Low-er Main Landing Gear and Actuating Mechanisms Lubrication, TASK 12-21-14-640-801-001 . SUBTASK 32-53-03-420-005 (3) Do this task: Nose Landing Gear Torsion Link Connection, TASK 32-21-11-400-803 . AMM Manual for 777-200


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Appendix XX Aircraft Maintenance Manual, 32-45-04-700-801

TIRES - INSPECTION/CHECK 1. General

A. The steps that follow are to examine the landing gear tires while they are installed on the airplane. They are to make sure that the tires used on the air-plane are in good condition for safe operation and minimum airplane mainten-ance. B. If the tires have flat spots or are blown because of a locked wheel slide (not a tire structural failure) refer to AMM 05-51-16/201 to find the cause. C. Airplane Eff. Wheel Position Tire Size 001-010 NOSE 42x17,0R18 26PR 001-010 MAIN 50x20,0R22 32PR D. The 777 aircraft (eff. 001-010) are equipped with radial tires. Both the main wheel and nose wheel tires consist of four major areas: the tread, sidewall, carcass and bead(s). The tread is a layer of reinforced rubber on the outer cir-cumference of the tire which forms its wearing surface. The tire is constructed with a cut protector between the tread and the top of belt plies to prevent damage to the tire belts. Belt plies to restrain the tire outer diameter are laid between the tread area and top carcass ply. The tread, together with the side-wall, protects the carcass from cuts and wear, and from deterioration due to moisture and sunlight. The carcass, or cord body, is composed of layers of cord bonded together by rubber. Each layer is called a ply. The beads, which are composed of steel wires embedded in rubber, form the base that holds the tire on the wheel. Figure 601 shows a cross-sectional drawing of a typical radial aircraft tire and gives the correct nomenclature for the various areas of a tire.

2. Tires Inspection

C. Procedure SUBTASK 32-45-04-KLM-XXX (

(1) Prepare for Inspection/Check (a) Check that landing gear ground locks are installed and wheels are chocked.. SUBTASK 32-45-04-KLM-XXX

WARNING: IF AN AIRPLANE HAS HAD AN ABORTED TAKEOFF OR IF HIGH WHEEL TEMPERATURE IS SUSPECTED, APPROACH WHEELS ONLY FROM FRONT OR REAR UNTIL BRAKES AND WHEELS ARE COOLED DOWN TO TOUCH BY HAND, OR AFTER AIR PRESSURE HAS BEEN RELEASED BY BLOWN FUSE PLUGS. IF POSSIBLE, PLACE BAGAGE CARTS OR SIMULAR OBJECTS AS CRASHBARRIERS OUTBOARD OF MLG WHEELS, UNTIL WHEEL ASSEMBLIES ARE SAFE TO HANDLE.


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(2) Examine Tires (a) Examine tires for wear, damage, defects, failures and contamination. Re-move from service (Ref 32-45-01/-02, Main/Nose Gear Wheel - R/I), tires ex-hibiting the following conditions and exceeding the limits mentioned. It is rec-ommended to measure the pressure of a tire, which will be removed, before starting removal, to determine if adjacent wheel on the same axle has been overloaded.

NOTE: In some cases different limits are provided for home base ver-sus line stations, this in order to prevent replacements on line stations. When deemed necessary, deviation from the recommended “home base limit” is allowed provided that the “line station limit” is not ex-ceeded. NOTE: When in special cases a worn/damaged tire is released for fur-ther flight (within the described limits herefore), enter the condition of the tire into the Aircraft Maintenance Log (AML) for action at next sta-tion or home base.

(3) Damage and wear types:

(a) Normal Tread wear. 1) Home base

a) In order to reduce replacements on line stations, it is recom-mended to remove tires at home base at a remaining groove depth of 0.8 mm or less. b) With the current tread designs the cut protector may become exposed in the center part of the tread, while the remaining depth of the adjacent grooves has not reached their removal limit yet. (see figure 601). Cut protector exposure in any portion of the tread section is no reason for tire removal.

2) Line station a) In general a tire must be removed from service when the tread has been worn down to the bottom of any groove at any circum-ferential location. b) With the current tread designs the cut protector may become exposed in the center part of the tread, while the remaining depth of the adjacent grooves has not reached their removal limit yet. (see figure 601). Cut protector exposure in any portion of the tread section is no reason for tire removal.

NOTE: At transit stops an aircraft may be released for flight with one tire on each axle at wear limit if not more than 5 landings will be accumu-lated before landing at another line station or home base. Enter remark in A/C log that the concerned wheel must be replaced at that station or home base.

(b) Shoulder wear 1) The main wheel tires may exhibit an unusual wear phenomenon where the tread on the shoulders wears much faster than the tread on


30

the crown (Ref. to Fig. 602). This phenomenon is called shoulder wear or step wear. NOTE: At transit stops an aircraft may be released for flight with one tire on each axle at wear limit if not more than 5 landings will be accumu-lated before landing at another line station or home base. Enter remark in A/C log that the concerned wheel must be replaced at that station or home base.

(c) Flat spots and rubber reversion. 1) A flat spot is an oval-shape area in the tread, which may extend to or into the carcass plies. This condition is caused by a skid (Ref Fig. 603, view A.). 2) Tread rubber reversion is an oval shape area in the tread similar to a skid flat spot, but where the rubber shows burning due to hydro planing during landing (Ref. Fig. 603 view B.). This condition is usually caused by wet or ice-covered runways. 3) Flat spot and rubber reversion in the tread is acceptable, provided that no groove bottom is worn away in a continuous length greater than the tread width and that there are no crew complaints indicating vibra-tion by concerning wheels.

(d) Cuts 1) The cuts that may be found on a tire are divided into four groups, namely: • - Circumferential cuts • - Transverse cuts • – Sidewall cuts • – Multiple cuts a) General limit

1. In general, a tire must be removed from service immediately, if one or more belt plies are cut or broken.

NOTE: Do not confuse cut protector with carcass plies (Ref Fig. 601). b) Circumferential cuts

1. Refer to Fig. 603 view C for general limits. 2. At home base, a tire with a circumferential cut may remain in service provided the cut protector is not exposed. 3. At line stations such a tire may remain in service provided that the limits in Fig. 603 view C are not exceeded.

c) Transverse cuts 1. Refer to Fig. 603 view D for limits. Under no circumstances should these limits be exceeded.

d) Sidewall cuts 1. At home base sidewall cuts are acceptable to any length only if the carcass plies are not exposed. 2. At line stations such cuts are allowed to any length even if the carcass plies are shown. If one or more carcass plies are broken or cut, the tire has to be removed immediately.

e) Multiple cuts 1. At home base no more than one cut to the maximum accepta-ble limits as mentioned under "circumferential cuts", “transverse


31

cuts” and "sidewall cuts" is permitted in any 90° segment of the tire. 2. At line stations three cuts to these maximum limits are permit-ted in any 90° segment of the tire, provided that not one cut is closer than 200 mm to the other.

(e) Punctures 1) A puncture is a hole penetrating through the tread into the car-cass. 2) At home base tires with holes that penetrate into the belt plies should be removed from service. 3) At line stations tires with holes more than 3 mm in diameter or holes penetrating more than 2 belt plies in the tread area, should be removed from service.

(f) Bulges and blisters. 1) Bulges or blisters (Ref Fig. 603, view E) are indications of tire tread separation. 2) Tires with bulges or blisters must be removed immediately ; tread separation may occur on next take-off. 3) Before the tire is deflated and removed, mark the location of the bulge or blister.

(g) Chevron cutting. 1) Chevron cuts (Ref. Fig. 603, view F) are usually caused by grooved runways. When an aircraft touches down, the tires are rotated rapidly and damaged by the runway groove edges. 2) Cuts across a tread rib (groove to groove) or cuts exposing the reinforcement plies are reason for tire removal.

(h) Groove cracking and rib undercutting. 1) Groove cracking is a circumferential crack or split at the base of a tread groove. Rib undercutting is an extension of groove cracking under the tread rib (Ref. Fig 603, view G). 2) At home base any tire with groove cracking or rib undercutting shall be removed from service. 3) At line-stations a tire with groove cracking, no longer than 50 mm, may be released for flight, providing that no belt plies are broken or out. A tire with rib undercutting of 3 mm or more under the tread rib has to be removed from service.

(i) Bead damage 1) Heat damage.

a) Heat damage to a tire may be found just around the wheel flange area. This bead damage requires an immediate tire replacement (See WARNING, par. 3.). 2) Bead wire protrusion.

a) A bead wire protruding the tire through the sidewall or bead area is an indication of a failed wire bead (bundle). Such a tire must be replaced before next flight.


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(j) Tire defects/failures 1) The wheel and tire assy has to be replaced immediately and sent together with as much tire remainders as possible to base shop for inspection/investigation and overhaul after experiencing one of the following defects and failures:

a) Burst tire. b) Completely or partly thrown tread. c) Tire overloaded by rolling the aircraft with neighbour tire collapsed. Total loss of inflation pressure. d) Tire overloaded by rolling the aircraft with neighbour tire collapsed.

2) Mark reason of removal on the tire. (with chalk or label) (k) Contamination of tires.

1) Landing gear tires will be severely damaged by Fuels, Mineral Oils, Solvents such as White Spirit, Aceton, MEK, Chlorothene, Greases, Turbo Oils and Hydraulic Fluids. Contamination of tires with any one of these fluids must be avoided at all times. 2) Do not place an aircraft with tires into spilled fluid. Protect the tires during maintenance with covers made of resistance cloth. 3) Cleaning Method.

a) If a tire becomes contaminated, the tire should be wiped off with soap and water or a mild detergent or an approved water-base aircraft cleaning-compound (e.g. Guminatol-S, Turco Jet Clean B). b) Wash the contaminated tires thoroughly, rinse with clean water and preferably dry with pressurized air.

4) Damage caused by Hydraulic Fluid. a) If the surface of the tire appears soft, spongy, or there are bulges present, the tire should be removed from ser-vice as soon as practical.

D. Marking of Removed Wheel and Tire Assies

(1) The reason for removal of the removed wheel and tire assies must be ac-curately recorded on the applicable tag, e.g. :

(a) Worn. (b) Damaged by cuts, cracks, blisters, overheating, etc. (c) Underinflation/leak. (d) Overloaded (due to flat/underinflated tire on the same axle). (e) Melted fuses on wheel. (f) Rejected take-off etc. NOTE: This will be most helpful for shop and engineering people and the retreader to control and evaluate these tires for possible perfor-mance improvement.


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Appendix XXI Process report

After finishing the report, of project landing gear, the group will give a group evaluation. In this evalua-tion the course of the project will be clarified. In the first meeting of group 2A2I the first personal details were explained. After brainstorming different subjects were formulated and subdivided between the group members. Because of this start the basic information for the starting document where quickly found and perso-nated to the group. At the end of the second week this resulted in a “go”, given by the project lecturer, Bob Hogervorst. In this start document a work schedule and a chairman and minutes secretary schedule where added. On those schedules the meetings where based, which were always prepared by the chairman and noted by the minutes secretary. This resulted in efficient meetings whereby all appointments were recorded in the end of the minute. Because of a good schedule there were only short and efficient meetings during the writing of chapter one. During those meeting it became clear that the calculations in chapter two were more difficult than expected, and that it could not be written in the planned time. This resulted in a delay and extra meetings. It was also very difficult to find the right en specific infor-mation about the, material, forces and dimensions of the landing gear. During a meeting in week five the group decided to split in four groups of two, in case two groups could focus on chapter two and two groups on chapter three. After this decision the group was able to write the chapters rapidly, and finish on time. This decision also concluded in changes in the work schedule. During the planned beamer sessions it became clear that Thijs Kuijs was not capable enough to write a subchapter on his own, due to his dyslexia. Therefore the group has attended him trough, by assist-ing him with writing. After several discussions with Thijs and a official warning for the late finishing of his subchapter, his writing level increased. Further no friction occurred. An improvement point for the next projects is to increase the research and avoid calculation problems. The group was forced to work hard and in the end got the project finished on time. As a last opinion, all the group members left a positive and motivated impression. Herby the distribution of task: Task Performed by Comment 1 Analysis of the landing gear

Anouk

1.1 Introduction landing gear B777 Ben

1.1.1 Purpose Ben

1.1.2 Lay-out Ben

1.2 Materials: Jeroen

1.2.1 Material: Steel Jeroen 1.2.2 Material: Aluminum Jeroen 1.2.3 Material: Titanium Bert 1.2.4 Material: Carbon Bert

1.3 Structural shock absorbing Tom

1.3.1 Shock strut and torque links Tom

1.3.2 Side braces and locks Tom

1.3.3 Air ground logic Thijs

1.4 Deceleration Thijs

1.4.1 Brakes Anouk

1.4.2 Auto brake Thijs

1.4.3 Anti-skid Ben

1.4.4 Brake temperature indication Thijs

1.5 Taxiing Anouk

1.5.1 Nose wheel steering Anouk


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1.5.2 Main gear steering Anouk

1.5.3 Wheels Anouk

1.6 Retraction and extension Mike

1.6.1 Retraction Mike

1.6.2 Extension Mike

1.7 Regulations Vito

1.7.1 CS-25 Vito

1.7.2 MEL Tom

2. Forces and moments on the landing gear.

Ben

2.1 Dimensions and weight Jeroen

2.2 Forces during taxi turn Jeroen, Mike (Tom, Thijs) Tom en Thijs overgezet naar H3

2.2.1 Calm Jeroen, Mike (Tom, Thijs) Tom en Thijs overgezet naar H3

2.3 Forces on the tires during land-ing

Anouk, Ben (Vito, Bert) Vito en Bert overgezet naar H3

2.3.1 Calm Anouk, Ben (Vito, Bert) Vito en Bert overgezet naar H3

2.3.2 Crosswind Anouk, Ben (Vito, Bert) Vito en Bert overgezet naar H3

3. Failures and involved costs Mike

3.1 Main gear steering Tom

3.1.1 Cause Tom

3.1.2 Consequence Tom

3.1.3 Maintenance Tom

3.1.4 Costs Thijs

3.2 Wheel failure Bert, Vito

3.2.1 Cause Bert, Vito

3.2.2 Consequence Bert, Vito

3.2.3 Maintenance Bert, Vito

3.2.4 Costs Bert, Vito

3.3 Conclusion Bert, Vito


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Appendix XXII List of abbreviations

AES Alternate Extension System

AIMS Aircraft Information Management System

ALA Amsterdam Leeuwenburg Airlines

AML Aircraft Maintenance Log

AMM Aircraft Maintenance Manual

AOG Aircraft On Ground

B772 Boeing 777-200

BSCU Brake System Control Unit

BTMS Break Temperature Monitoring System

CS-25 Certification Specifications-25

EASA European Aviation Safety Agency

EICAS Engine Indicating Crew Alerting System

ELMS Electronic Load Management System

FAA Federal Aviation Administration

Ft/sec Feat per second

HIL Hold Item List

Kg Kilogram

Kts Knots

LG Landing Gear

MAX Maximum

MEL Minimum Equipment List

MGSCU Main Gear Steering Control Unit

MLG Main Landing Gear

MMEL Master Minimum Equipment List

MTOW Maximum Take-Off Weight

MLW Maximum Landing Weight

MTW Maximum Taxi Weight

NLG Nose Landing Gear

PCA Power Control Actuator

PSEU Proximity Switch Electronics Unit

Psi Pressure per square inch

RH Right Hand

RTO Retracted Take Off

Sec Seconds

WOW Weight On Wheels