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关于发动机前吊架整流罩盖板封严损伤标准

SR 3-5454271361，HNA-HNA-21-0556，HNA-HNA-23-2381-10B

由于手册没有检查标准，波音当前均采用一事一议的方式。

以下案例的损伤情况，波音提供了RDR做为临时修理方案，保留100CY。（2023年后申请未得到批准）

封严：311A2535-31/311A2535-32/311A2535-33/311A2535-34

吊架整流罩盖板封严检查可以由如下项目涵盖:

1.区域检查MP70-800-01 (T=R=120CA)和70-810-02(T=R=120CA)。JC-73N-70-810/820-02

2. 航后检查工卡QZ-AF。

2023年10月补充案例

Boeing has reviewed the Ref /A/ messae and finds that the proposed time limited repair is NOT acceptable due to the location of the seals. The seal is within the fire zone of the engine per FAR 25.867 and required to be fire resistant.There are no fly on limits for continued revenue fight operations with seal section missinp or damaged. The proposed BMS 5-95 sealant is not acceptable to use in location with temperatures more than 180 degrees F (82 degrees C),Therefore the use of BMS 5-95 with speed tape wil not adequately protect the structure during a fire event.
1、Boeing recommends either the seal be replaced prior to any flight, or as a time-limited repair apply BMS 5-63 sealant to any gap with missing sealI inspect at 500 hour intervals to ensure that the sealant intact, Replace the damaged seal if further deterioration is found during repeat inspection. Boeing Recommends replacing the damaged seal at the next available opportunity, to be no later than 200 flight cles or 30 days time limit.

2、Boemg notes that BM 5-63 can have up to 72 hour cure time howeve, this can not e avoided. Beimg states that the manufacturers cure tim nstrucions for the BMS 5-63 type must be adhered too.

3、To prevent heat damage to the seal in the future and potentialy to the strut fairing panel as well, Boeing recommends checking the AMM 54-52-0 aerodnamic smoothmes recuirements at strut T/R fairing to T/R aft cowl when rigging the T/R.The allowable steps is +.0750 IN to -.1200 IN larger negative steps could result in a gap that allows hot air to vent and can cause damage to the strut faring mpanel.Reter to AMM 78-31-01/501 to adjust the T/R and increase latch pressure as reduired to correct the thrust reverser pap condition.
Our review of the guidelines provided in Boeing Service leter 737-SL-51-041 indicates this repair can be considered minor repair. Enclosed is the Ref / Repair and Devation Record RDR)form that documents acceptance of this repair data.

反推上部盖板431EL、431ER、441EL、441ER的封严受高温（约215F，封严耐450F）和高速气流的影响，在使用后出现损伤。由于SRM手册中并未给出允许损伤的标准。在经历了多次的CASE BY CASE沟通后，分别于2021年4月和2022年11月两次向波音提出机队性的放行标准申请。均被波音以需要符合FAR 25.867防火性要求，需根据每个案例的判断拒绝，建议制定合适的GVI检查间隔来发现。因此结合局方要求，编写了培训教材，并在定期工卡中加入了检查图示。后续延续运行中决策，和单起事件逐个向波音报批的政策，一些不严重的损伤会得到波音临时修复的审批。最初使用BMS5-95加金属胶带，可以作为临时措施并提供RDR。后来改为BMS5-63加金属胶带。

2023年11月更新，HNA-HNA-23-2381-10B 波音认为当损伤的间隙低于0.125英寸，是可以使用BMS 5-63来修理，可以通过加温来加速固化。并按100FC来进行目视检查，500FC完成更换。如果大于了0.125英寸需要更换。

  1. If HNA detect any gap between Pylon Strut Panel and Fairing of Thrust Reverser up to 0.125”, it may be
    repaired with BMS5-63 sealant to completely close this gap. However, if the any detected gap is higher
    than 0.125”, this seal shall be removed and, replaced by a new one.
  2. The BMS5-63 sealant has to be completely cured per BAC5000 requirements.
  3. A Detail Visual Inspection (DVI) shall be done every 100FC as stated in Ref /C/ message.
  4. This procedure is a temporary repair and, the damaged seal shall be replaced in the first opportunity and
    after 500FC per Ref /C/ message.

  1. No large gaps exceeding 0.125 inch wide are allowed in thesteady showed in Ref /C/ message and Red /D/ sketch. f any gap up to 0.125″is detected, this gap shallbe flled with BMS5-63 sealant as a temporary repaiSurface damage made by erosion etc. can be filled with BMS5-63 sealant and properly cured per BAC 5000.2. Corect. Any detected gap shall be flled with BMS5-63 sealant as temporary repair. 500 fight hours (FH) maximum.3.The ss-3 type, cs B-4has ure me f 40 hous Bmn pec BAC5-be xm) eded the ure ofM-3 seant ma be tceleratedhy sg condurcte heat with mamumt temperture of145F ts
    surface
  2. If the gap is greater than 0.125 inch, the damaged seal shabe replaced by a new one. Please note that the area is critical for fire as it is at the enaine exhaust region.5. Boeing recommends a Detail Visual inspection (DVI) at ever100 Flight Hours (FH) and replacement of the seal at a maximum of 500 Flight Hours (FH).

关于胎压能否突破手册上限的问题

SR 4-5669181453

由于胎压与胎皮使用循环数息息相关，针对能否提高现行胎压标准，与波音做了较多的沟通。最终波音的解释如下：

一是胎压变化影响轮胎与地面接触面，与设计的刹车距离会有差异；

二是轮舱内爆胎的取证压力问题，对其他管路、线路等的影响。基于以上初始适航取证问题，不可以进行随意调整。

因而与轮胎本身额定设计压力会存在一些区别。

Even though Ref /A/ reference guide lists a MLG tire pressure higher than what is required in Ref /B/, Boeing notes that 737-800 is certified to operate only at MLG tire pressures specified in Ref /B/.

Increasing the tire pressure above allowable limits changes the tire footprint on the ground which directly affects its certified stopping distance.  In addition, the airplane wheel well components (cables, pipes, brackets, etc.) were all certified to withstand potential tire burst event at maximum pressure as listed in Ref /B/. Operating MLG tire pressures higher than values specified in Ref /B/ would be deviating from allowable airplane certification limitations and are therefore not authorized.

关于737BCF出现混合总管温度传感器导致的再现组件灯亮

外部航司案例

有飞机左组件频繁反应再现组件灯亮的问题，故障代码指向左侧混合总管温度传感器，经对串传感器、ZTC、PFTC和线路检查未见异常，故障依旧反复发生。经与波音沟通，反应该现象在BCF飞机上偶有发生，认为是由于TCV的热气与ACM冷气混合不均，导致传感器感受到了200F的温度超过6.2秒，从而记录信息，可以通过加电阻的方式缓解。

Boeing have already revived couple of similar reports from other 737-800BCF operators. The root cause for this chronic left mix manifold sensor fault was determined to be poor mixing of the hot (TCV open) and cold air at the left mix manifold sensor. This resulted in the sensor detecting about 200 degrees Fahrenheit air temperature in a heating mode for more than 6.2 seconds, thus triggering the Mix Manifold Temperature Sensor Short Fault. The solution is to add a 200 ohm inline resistor to the mix manifold sensor. The resistor(s) are to be installed near E3-3 D41800P (reference
Wiring Diagram Manual (WDM) section 21-51-12) for both left and right (optional) mix manifold sensors. For detailed work instructions, PNs and RDR (Repair and Deviation Record), please have your avionics engineer submit a Service Request.

波音考虑到这是假信息，只要可以复位，允许持续运行。

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