1、1,A320前輪轉(zhuǎn)彎系統(tǒng) 介紹及維護(hù) 一車間 李輝,2,一、背景介紹,3,The steering system uses the green or yellow hydraulic system to operate a steering actuating cylinder, which changes the direction of the NLG wheels.,飛機(jī)在地面滑行時(shí)的方向控制，幾乎完全依賴于前輪轉(zhuǎn)彎系統(tǒng)NWS來(lái)操作完成。 如果前輪轉(zhuǎn)彎系統(tǒng)出現(xiàn)故障，機(jī)組將無(wú)法掌控飛機(jī)的滑跑方向，從而使飛機(jī)偏離或沖出跑道、滑行道，輕則損傷飛機(jī)設(shè)備，嚴(yán)重的甚至?xí)斐扇藛T的重大傷亡。 因此，對(duì)

2、于前輪轉(zhuǎn)彎系統(tǒng)相關(guān)故障，必須按手冊(cè)謹(jǐn)慎處置。,4,Jetblue Airbus performs a low pass for the LGB tower for a nose gear inspection, and as you can see the nose gear is in a 90-degree position. Following the flyby, the aircraft spent the next 2 hours flying over the Pacific Ocean just off Long Beach burning fuel before divert

3、ing to LAX for an emergency landing, which happily was a succesful one without injuries.,Jetblue A320-232 (N536JB) 前起落架減震支柱上支撐防轉(zhuǎn)凸耳損傷被剪切斷裂,導(dǎo)致前輪空中偏置90度，于Los Angeles airport (LAX)執(zhí)行應(yīng)急著陸。,5,JetBlue 292 BUR-JFK makes its emergency landing at LAX. The front gear was turned perpendicular to the runway caus

4、ing the sparks and smoke.,6,LTE International Airways A320-214 在著陸滑跑過(guò)程中因前輪轉(zhuǎn)彎系統(tǒng)故障，導(dǎo)致偏離跑道，前輪陷入跑道旁邊的草地。,7,二、系統(tǒng)介紹,8,SYSTEM OVERVIEW,9,The steering system receives hydraulic pressure in the following conditions:,- A/SKID & N/W STeeRinG switch is in ON position, - towing control lever is in normal positio

5、n, - at least one ENG MASTER switch is ON, - aircraft is on ground.,10,The steering system is controlled by the BSCU, which receives order from:,- the steering hand wheels (orders added algebraically), - the rudder pedals, - the autopilot.,11,前輪轉(zhuǎn)彎角度限制,12,Handwheels,During taxi, and more generally at

6、 low speed, through action on a handwheel. There are two identical handwheels: one for the Captain, one for the First Officer. In the event of simultaneous operation, the orders that the handwheels give are algebraically added. The maximum travel of the wheels is plus or minus 74 deg. The maximum co

7、rresponding travel of the handwheel is plus or minus 75 deg. The law between these two travels is not linear.,13,The steering angle is limited as a function of the aircraft speed.,（手輪偏轉(zhuǎn)角度與前輪轉(zhuǎn)彎角度比例關(guān)系）,（手輪操作時(shí)前輪轉(zhuǎn)彎角度與飛機(jī)速度的限制關(guān)系）,20KTS以內(nèi)，最大行程操作,速度高于70KTS，使用手輪轉(zhuǎn)彎無(wú)效,14,Rudder pedals,During takeoff or landing

8、, and more generally at high speed： - either through action of the Captain (or First Officer) on the rudder pedals, - or automatically through the autopilot (yaw control).,In the event of simultaneous operation, the orders that the handwheels and pedals give are algebraically added.,15,PEDALS DISC按鈕

9、可在以下情況脫開腳蹬對(duì)前輪轉(zhuǎn)彎的控制： During rudder ground check. The runway is icy. Pilot can disconnect the control through the pedals from the steering control.,When the aircraft speed is above 130 knots, the steering is not available,（腳蹬操作時(shí)前輪轉(zhuǎn)彎角度與飛機(jī)速度的限制關(guān)系）,16,Nose Wheel Steering Servo-Control (6GC) enhanced type

10、,圖示為增強(qiáng)型A320系列飛機(jī)，區(qū)別在于選擇活門位置與classic 不同,液壓使用的是黃系統(tǒng),17,Nose Wheel Steering Servo-Control (6GC) classic type,傳統(tǒng)型的6GC將選擇活門作為部件嵌入到整體中。液壓選用的是綠系統(tǒng)。,18,Nose Wheel Steering Servo-Control (6GC),Selector valve,Bleed screw,Anti-shimmy accumulator,Servovalve,19,Nose Wheel Steering Servo-Control (6GC) main component

11、s,An electrically-operated selector valve and its slaved valve. When the selector valve is energized, the pressure is applied to the servovalve. A servovalve of the deflection-jet type, equipped with a LVDT sensor which detects the position of the slide valve. An adjustable diaphragm located on each

12、 output line of the servovalve, this diaphragm is used to adjust the flow to each actuating cylinder chamber and consequently the wheel steering speed. A by-pass valve which interconnects the two chambers of the steering cylinder in the event of hydraulic system depressurization. An anti-shimmy accu

13、mulator with a built-in pressure-relief valve, It can supply fluid pressurized to 15 bars in case of cavitation in one chamber of the cylinder, initiated by the shimmy. A screw for the bleeding and/or depressurization of the hydraulic block.,20,對(duì)于傳統(tǒng)型A320飛機(jī)，由于前輪轉(zhuǎn)彎系統(tǒng)使用的是來(lái)自前起落架艙門關(guān)閉油路的綠系統(tǒng)液壓壓力，因此，在飛機(jī)執(zhí)行重力

14、放起落架的程序后，前輪轉(zhuǎn)彎系統(tǒng)將無(wú)法工作，需用拖車拖回停機(jī)坪。,使用重力放起落架的英航A320-214在近進(jìn)階段,21,Nose Wheel Steering Feedback Sensor (3GC, 4GC),P/N: E21336000,P/N: C24763000 (ON A/C 001-013 ),22,Nose Wheel Steering Feedback Sensor (3GC, 4GC),Two identical RVDT sensors give the position of the rotating tube. The RVDT sensor is driven by

15、 a reduction gearbox attached to the landing gear strut. 3GC is part of the electrical channel of the steering control, 4GC is part of the monitoring channel.,23,The control channel acts on the servovalve as a function of the difference in position between the handwheel (in the cockpit) and the whee

16、ls. The monitoring channel delivers in a similar manner a signal which represents the position of the slide valve in the servovalve.,3GC for control,4GC for monitoring,NWS 系統(tǒng)工作原理,24,swivel selector valve,When the landing gear starts to retract, the swivel selector valve cuts the hydraulic power supp

17、ly and connects the hydraulic block to the reservoir return line.,旋轉(zhuǎn)選擇活門與前起落架收放支點(diǎn)同軸，前起放下使活門內(nèi)部液壓流向前輪轉(zhuǎn)彎作動(dòng)系統(tǒng)。,25,steering actuating cylinder,轉(zhuǎn)彎作動(dòng)筒內(nèi)部為：活塞推動(dòng)齒條與前起落架轉(zhuǎn)動(dòng)筒的半齒輪機(jī)構(gòu)嚙合作動(dòng)，通過(guò)后部的上、下扭力臂驅(qū)動(dòng)前起落架減震器完成轉(zhuǎn)彎動(dòng)作。,anti-shimmy valve,26,減震支柱從前起落架內(nèi)拔出后，可以看出前輪轉(zhuǎn)彎作動(dòng)筒驅(qū)動(dòng)的是中間的旋轉(zhuǎn)筒。,前起落架減震支柱被拔出，扭力臂的下端仍然在位。,27,三、維護(hù)要點(diǎn),28,1、關(guān)于3

18、GC、4GC的維護(hù),由前面的介紹可知：3GC、4GC的反饋信號(hào)的準(zhǔn)確性對(duì)整個(gè)轉(zhuǎn)彎系統(tǒng)的工作起到了決定性的作用。 針對(duì)機(jī)組反映的滑行中無(wú)法保持直線（偏左或偏右）的問(wèn)題，在排除了側(cè)風(fēng)、道面狀況、機(jī)輪狀態(tài)以及機(jī)組操作方面的原因后，需要對(duì)3GC進(jìn)行微調(diào)。 調(diào)節(jié)或更換傳感器，請(qǐng)嚴(yán)格遵守AMM程序！,29,前輪轉(zhuǎn)彎不當(dāng)或系統(tǒng)故障將導(dǎo)致輪胎的過(guò)量磨損，甚至爆胎,30,AMM手冊(cè)關(guān)于前輪轉(zhuǎn)彎0位的調(diào)節(jié)提供了9種程序，其主要區(qū)別就是采用了不同的基準(zhǔn)參考數(shù)據(jù)和3GC、4GC調(diào)節(jié)工具： 基準(zhǔn)數(shù)據(jù)： 1Rudder Trim Angle as Reference 2NLG Centering Cams as Refe

19、rence 3Nose-Wheel Alignment Tool 調(diào)節(jié)工具： For P/N C24763000： F26630200 或 M46196-100F26792000 For P/N E21336000：F26792000,31,AMM 32-51-00-820-00 x,1、Adjustment of the N/WS Zero Position with the Adjusting Tool F26630200 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000, Rudder Trim Angle as Reference 2、

20、Adjustment of the N/WS Zero Position with Adjusting Tool M46196-100 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000, Rudder Trim Angle as Reference 3、Adjustment of the N/WS Zero Position for A/C with N/WS Sensor Box (3GC, 4GC) P/N E21336000, Rudder Trim Angle as Reference 4、Adjustment of the N/WS

21、Zero Position with the Adjusting Tool F26630200 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000, NLG Centering Cams as Reference 5、Adjustment of the N/WS Zero Position with the Tool M46196-100 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000, NLG Centering Cams as Reference 6、Adjustment of the N/

22、WS Zero Position for A/C with N/WS Sensor Box (3GC, 4GC) P/N E21336000, NLG Centering Cams as Reference 7、Adjustment of the N/WS Zero Position with the Adjusting Tool F26630200 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000 with the Nose-Wheel Alignment Tool 8、Adjustment of the N/WS Zero Position

23、 with Adjusting Tool M46196-100 for A/C with N/WS Sensor (3GC, 4GC) P/N C24763000 with the Nose-Wheel Alignment Tool 9、Adjustment of the N/WS Zero Position for A/C with N/WS Sensor Box (3GC, 4GC) P/N E21336000 with the Nose-Wheel Alignment Tool,32,前起落架支撐主結(jié)構(gòu)與旋轉(zhuǎn)筒之間有一個(gè)前輪定中的目視指示標(biāo)記，上下刻度標(biāo)志線對(duì)齊的時(shí)候?yàn)轱w機(jī)支線滑行（前輪

24、轉(zhuǎn)彎0位）。注意：此標(biāo)記僅僅作為維護(hù)中的快速參考標(biāo)記，在對(duì)轉(zhuǎn)彎系統(tǒng)的調(diào)節(jié)中不作為前輪定中的參考標(biāo)準(zhǔn)，AMM無(wú)此標(biāo)志線作為定中參考的調(diào)節(jié)程序！,33,轉(zhuǎn)彎系統(tǒng)測(cè)試對(duì)輔助設(shè)備的要求,注意：在AMM和TSM中，關(guān)于在地面對(duì)前輪轉(zhuǎn)彎進(jìn)行操作測(cè)試時(shí)都必須使用輔助設(shè)備以減小輪胎與地面的摩擦力矩對(duì)轉(zhuǎn)彎操作精準(zhǔn)性的影響。可以采用： 1、用兩塊平面鋼板，中間涂抹足量潤(rùn)滑油脂，之后鋪入前輪與機(jī)坪地面之間。此法方便實(shí)用，比較常用。 2、使用千斤頂?shù)慕M合，將前輪推離地面。此法較為復(fù)雜，對(duì)設(shè)備要求較高，較少使用。,34,P/N C24763000傳感器的調(diào)節(jié),傳感器齒輪箱調(diào)節(jié)工具：F26630200 安裝于傳感器與齒輪

25、箱之間，通過(guò)微調(diào)減速齒輪的位置來(lái)得到正確的傳感器0位（通過(guò)F26792000傳感器電壓測(cè)試裝置得出的U1、U2電壓值在合適的比例范圍內(nèi)）,傳感器電壓測(cè)試裝置：F26792000 安裝于BSCU線路與傳感器3GC或4GC之間，借助電壓表可讀出RVDT內(nèi)部U1、U2兩級(jí)線圈的電壓值，調(diào)0工作就是圍繞這兩個(gè)電壓差值進(jìn)行齒輪箱內(nèi)傳動(dòng)齒輪的微調(diào),35,傳感器齒輪箱調(diào)節(jié)工具：M46196-100 調(diào)節(jié)原理與前面所提工具相同，但無(wú)法與傳感器3GC（4GC）同時(shí)安裝，調(diào)節(jié)齒輪箱后需要拆下，才能用電壓測(cè)試裝置讀取U1、U2,36,P/N E21336000傳感器的調(diào)節(jié),傳感器電壓測(cè)試裝置F26792000 安裝

26、于BSCU線路與傳感器3GC或4GC之間，借助電壓表可讀出RVDT內(nèi)部U1、U2兩級(jí)線圈的電壓值。傳動(dòng)齒輪的調(diào)節(jié)也是在位調(diào)節(jié)。,37,CAUTION:IF THE SENSOR BOX HAS P/N E21336000, NEVER REMOVE THE SENSOR FROM THE GEARBOX. THE SENSOR AND THE GEARBOX ARE AN ASSEMBLY THAT YOU MUST NOT DISASSEMBLE ON THE AIRCRAFT.IF YOU REMOVE THE SENSOR FROM THE GEARBOX:- YOU WILL CAUS

27、E DAMAGE TO THE SENSOR BOX- THE ADJUSTMENT OF THE SENSOR BOX WILL NO LONGER BE CORRECT.,如果U1、U2數(shù)據(jù)不在范圍內(nèi)，則需要調(diào)節(jié)RVDT上部的傳動(dòng)齒輪機(jī)構(gòu)，對(duì)調(diào)節(jié)蝸桿（worm screw)進(jìn)行調(diào)節(jié)之前需要松開圖中2的四個(gè)固定螺栓（內(nèi)六角），以脫開傳感器與齒輪機(jī)構(gòu)的嚙合，否則無(wú)法作動(dòng)調(diào)節(jié)蝸桿。,調(diào)節(jié)蝸桿 Worm screw,38,松開四個(gè)固定螺釘后就可以對(duì)調(diào)節(jié)蝸桿5進(jìn)行旋轉(zhuǎn)調(diào)節(jié)。首先將調(diào)節(jié)蝸桿端部覆蓋的密封膠刮去，注意不要刮傷部件表面。露出蝸桿頭后，再用小一字刀輕輕旋轉(zhuǎn)，同時(shí)在電壓表上觀察U1U2的變化情

28、況，確認(rèn)U1 = U2 plus or minus 20 mV ，調(diào)節(jié)完成。 注意：調(diào)節(jié)蝸桿非常靈敏，輕微旋轉(zhuǎn)即可改變RVDT電壓值，嚴(yán)格按照程序操作，切忌蠻力擰緊或松。,調(diào)節(jié)蝸桿 Worm screw,39,3GC、4GC傳感器的拆換,對(duì)于P/N C24763000傳感器的拆換：傳感器與傳動(dòng)齒輪箱是相互獨(dú)立的部件，傳感器需要單獨(dú)拆裝，更換相對(duì)簡(jiǎn)單，安裝新件后需重新驗(yàn)證0位電壓。AMM 32-51-41也提供了齒輪箱的拆換程序，安裝的時(shí)候需要用到前面提到的校準(zhǔn)工具配合調(diào)節(jié)。 對(duì)于P/N E21336000傳感器的拆換：傳感器與傳動(dòng)齒輪組為一個(gè)整體部件，傳動(dòng)齒輪機(jī)構(gòu)加載有彈簧偏置力，拆換或串件時(shí)

29、必須注意機(jī)構(gòu)0位的調(diào)節(jié)和推桿鎖銷的使用。,40,一架IBERIA 的A320-214在推出后，前輪轉(zhuǎn)彎系統(tǒng)故障，前輪偏轉(zhuǎn)90度，無(wú)法操作。,41,拆換P/N E21336000傳感器時(shí)應(yīng)嚴(yán)格按照AMM程序進(jìn)行,推桿鎖銷pushrod 在傳感器的安裝過(guò)程發(fā)揮很重要的作用：新的傳感器的傳動(dòng)齒輪組在內(nèi)部彈簧偏置力的作用下通常是處于最大行程的一側(cè)（已超出前輪轉(zhuǎn)彎最大角度），安裝前必須利用前面所提調(diào)節(jié)工具人工調(diào)回0位，然后按入推桿銷鎖定齒輪組（內(nèi)部齒輪保持在調(diào)節(jié)完畢的0位），再裝在前起落架的底座上，安裝完畢，拉出推桿銷解除對(duì)齒輪組的鎖定。,推桿鎖銷pushrod,42,對(duì)于B2403和B2374飛機(jī),由

30、于這兩架飛機(jī)的BSCU與深圳公司A320/319機(jī)隊(duì)其他飛機(jī)的件號(hào)不同，功能比其他飛機(jī)要先進(jìn)，在對(duì)這兩架飛機(jī)的3GC和4GC進(jìn)行調(diào)節(jié)或更換時(shí)，可以借助CFDS進(jìn)入BSCU的SPECIFIC DATASTEERING DATARVDTCOM&RVDTMON進(jìn)行兩個(gè)傳感器參數(shù)值的對(duì)比和快速調(diào)節(jié)，可以減少排故時(shí)間，具體參照AMM。 RVDTCOM為3GC探測(cè)到的前輪轉(zhuǎn)彎角度值 RVDTMON為4GC探測(cè)到的前輪轉(zhuǎn)彎角度值,43,2、對(duì)于Nose Wheel Steering Servo-Control (6GC) 的排故,以B2393前輪轉(zhuǎn)彎失效為例： 10/15航后B-2393滑行到位時(shí)，出現(xiàn)前輪

31、轉(zhuǎn)彎故障，自檢有前輪轉(zhuǎn)彎控制盒信息； 10/25杭州短停有BSCU信息，滑行手輪操作有較大偏差，飛機(jī)由拖車拖到機(jī)位，地面復(fù)位BSCU跳開關(guān)后正常； 10/30短停機(jī)組反映早上從深出發(fā)時(shí)，在滑行道上轉(zhuǎn)彎時(shí)，有前輪轉(zhuǎn)彎故障信息，無(wú)法轉(zhuǎn)彎，機(jī)組剎車后重置前輪轉(zhuǎn)彎防滯電門，正常，后續(xù)及回程都正常。短停查PFR曾有“STEERING ELEC BOX 5GC”信息，做BSCU測(cè)試正常。,44,針對(duì)NWS FAULT 的ECAM警告和STEERING ELEC BOX 5GC故障信息，TSM 32-51-00-810-833給出了詳細(xì)排故程序： 1、做系統(tǒng)測(cè)試，確認(rèn)故障現(xiàn)象和信息 2、根據(jù)測(cè)試結(jié)果選擇排故

32、方向,45,BSCU測(cè)試正常，根據(jù)TSM程序就要通過(guò)MCDU讀取BSCU內(nèi)的TROUBLE SHOOTING DATA，根據(jù)故障代碼再繼續(xù)明確排故方向和重點(diǎn)： B2393的BSCU故障代碼為 90,（此圖中FAULT CODE為B8）關(guān)于讀取BSCU內(nèi)排故數(shù)據(jù)和相關(guān)數(shù)據(jù)的解釋請(qǐng)參照 TSM D/O 32-42-00-030 .,46,針對(duì)故障代碼90，TSM將排故重點(diǎn)放在了6GC內(nèi)伺服活門上，并提供如下測(cè)試程序：,- Do a check of the servovalve - Put the aircraft in the necessary configuration to let the

33、 nosewheels move freely to the left or the right 其目的是通過(guò)實(shí)際操作前輪轉(zhuǎn)彎系統(tǒng)進(jìn)行作動(dòng)，通過(guò)查看并比較6GC內(nèi)伺服活門“定中位”的電流值（SSV CURRENT parameter ISV1或ISV2）是否處于正常范圍內(nèi)來(lái)判斷故障。 ISV1腳蹬操作完全左轉(zhuǎn)6度后恢復(fù)定中位伺服活門電流值 ISV2腳蹬操作完全右轉(zhuǎn)6度后恢復(fù)定中位伺服活門電流值,47,伺服活門在6GC中的位置與結(jié)構(gòu),48,伺服活門電流值ISV1或ISV2,對(duì)于ISV1和ISV2數(shù)值的正確范圍如下： - 0.5 X (ISV1 + ISV2) is less than or equal to plus or minus 0.5 mA. - (ISV1 - ISV2) is less than or equal to plus or minus 0.50 mA. B2393測(cè)出ISV1和ISV2分別為-0.74和-0.75 ，經(jīng)計(jì)算已經(jīng)超出上面所列范圍，可以判斷出：伺服活門在前輪轉(zhuǎn)彎處于定中位時(shí)（無(wú)操作信號(hào)），其內(nèi)部線圈的電流值已經(jīng)超出正常工作范圍。 更換6GC后做功能測(cè)試轉(zhuǎn)動(dòng)前輪正常，繼續(xù)對(duì)6G