油箱盖板渗漏新的处置办法

2024年11月12日,波音WTT会议介绍了一种新的改版处置办法,可供参考,整体意思是将盖板GASKET的所有漏油路径用胶封堵,然后使用金属胶带加固。处置后提供2FC的放行。

  1. Defuel aircraft per operator’s standard practice (Reference 737NG AMM 12-11-00)
  2. Accomplish a General Visual Inspection at the fuel leak location around the entire circumference of the access panel. Look for missing of pulled fasteners, cracks, corrosion.
  3. Using best available practice, solvent clean subject access panel clamp ring gaps using MEK per SOPM 20-30-03 in preparation for sealing application.
  4. Apply BMS5-45 Class B-1/2 sealant to the clamp ring gaps, ensuring the sealant is flush within the gaps around the full inner and outer circumference of the clamp ring. See Figure 1
  5. Locally clean lower skin surface and access panel surface using MEKper SOPM 20-30-03 in preparation for speed tape application.
  6. Apply speed tape (3M 425 or similar) over the subject access panel. See Figure 2 for typical tape application
  7. Refuel the main and center fuel tanks to the maximum fuel quantity for each fuel tank that can be used per operator’s standard practice (Reference 737NG AMM 12-11-00). Monitor the subject areafor 15 minutes to ensureleak free condition.
  8. If no leaks, restore aircraft fuel quantity for operators flight requirements. Otherwise, panel replacement is required.
  9. Ensure pilots are notified of the temporary repair.
  10. Before and after each subsequent flight, perform a General Visual Inspection of speed tape application integrity and to ensure the speed tape is still fully sealing the leak. Repair or reinforce tape as required.
  11. Replace the subject access panel at completion of 2 Flight Cycles..
    If Operator uses the above repair please report back to Boeing the results of the repairand/or repair procedural recommendations.

2024年12月更新,参考该方法执行快速封堵有效,大约工时1个小时。建议优先使用。

737MAX燃油箱盖板漏油

ISE-28-22-41015

AEROMEXICO在FIX发帖表示发现两块盖板渗漏,531BB & 631BB。在接近531BB时,发现了一个松动的螺钉,该螺钉根据AMM任务28-11-31-400-801拧紧,但泄漏仍在继续。Access 631BB具有正确的扭矩,但存在泄漏。此前从未发生过拆装。

多家航司跟帖:

***美国联合航空公司收到了3架不同飞机燃油面板泄漏的报告。其中一起飞机事故发生在2023年1月27日,一架737MAX-9飞机的燃料面板531AB和531BB被发现泄漏。第二次飞机事故发生在2023年2月2日,一架737MAX-8飞机的燃料面板532AB被发现泄漏。第三起事件发生在2023年3月29日,一架737MAX-9发现631AB号燃油泄漏。在所有三架飞机上,联合航空公司在发现泄漏之前都没有进入油箱或干扰燃油面板。美国联合航空公司为此提交了SR,并要求波音公司展开质量调查。

***新航表示,在737-8飞机加油期间,631BB检修门发现燃油泄漏。对高抗冲击检修门(631AB、631BB、531AB,
531BB、632AB和532AB)如下:
a) 将扭矩扳手设置为60 in-lb(并按扭矩顺序检查燃油检修门631AB、631BB、531AB、531BB、632AB和532AB上每个安装螺栓的扭矩。如果扭矩低于60 in-lb,则扭矩为65±5 in-lb。
631BB检修门的泄漏没有停止。此外,531BB检修门也发现泄漏。油箱已卸油,两个检修门都已拆下并重新安装。
新航已着手对五架具有不同扭矩值(60英寸-磅或30英寸-磅)的737-8飞机进行扭矩检查。如果扭矩低于60 in-lb,则将紧固件拧紧至65±5 in-lb。只有五分之一的飞机通过了扭矩检查。

附加说明:自飞机交付以来,所有这些高抗冲击检修门(631AB、631BB、531AB、531BB、632AB和532AB)均未受到干扰
。此外,737-8高抗冲击检修门的扭矩值为65 In-lb,高于737-800高抗冲击检查门的35 In-lb。

***flydubai(JXB)也经历了中央油箱检修门的燃油泄漏,包括近年来其737MAX机队中的年轻飞机上的531AB、531BB、631AB、631BB,早在生产后的2900个总飞行小时内就发生了泄漏。
报告泄漏的主要原因如下:
1.垫圈损坏P/N:112W8216-1(4次)
2.螺栓松动/扭矩不足(1次)
3.圆顶螺母开裂(1次)
4.橡胶门密封件损坏P/N:112W8214-1(1次)

每个检修门报告燃油泄漏的次数如下:
531AB=4次因垫圈损坏
531BB=2次(1次由于垫圈损坏,另一次由于橡胶门密封)
631AB=1次,因为圆顶螺母出现裂纹
631BB=2次,(1个圆顶螺母开裂,另一个在松动/扭矩不足的螺栓上)

flydubai认为,燃料泄漏不仅具有经济性(除燃料损失外的运营延误/AOG),还具有安全性影响,事故可通过发生燃料泄漏事件的运营商网络向当地监管机构和机场当局报告。
波音公司需要加快对这一问题的坚定审查和解决,因为多家运营商已经在这个FIX论坛上报告了737MAX机队中央油箱检修面板的泄漏。
邀请所有受影响的运营商就这一主题发表评论并分享他们的经验和统计数据,以进行集体努力并加快解决。

从航司报告看,主要是螺栓力矩不足导致的漏油,与此前的盖板乳突裂纹不太一样。机队RTS基本上都有C检,因此该情况不太突出。

中央油箱的诸多最低油量要求

SR HNA-HNA-24-0819-03B

在手册中,对于中央油箱油量要求有诸多的限制,且各不相同,为此与波音做了沟通,不同油量究竟是出于什么要求。相关解释如下。

1, FIM 28-22 TASK 801(Center Tank Left Fuel Pump LOW PRESSURE Light is ON – Fault Isolation), it requires a minimum fuel of 14,000 lb (6350 kg) .

  • 14,000 lbs. is a minimum amount of fuel required in the center tank to ensure the fuel pump will re-prime and will developed fuel pressure for the test.

2, FIM 28-22 TASK 817(Center Tank, Left Boost Pump Circuit Breaker Open – Fault Isolation), it requires a minimum fuel of 20,000 lb (9072 kg)  .

  •  20,000 lbs. is to ensure the pump inlets are covered for safety to protect against introducing an ignition source/ electrical short in the fuel tank. Note that FIM 28-22 TASK 817 specifically addresses an open circuit breaker fault.

3, AMM 28-22-41-720-802(Ground Fault Interrupter (GFI) – Operational Test), it requires a minimum fuel of 2000 lb (907 kg)  .

  •   2,000 lbs. is to ensure the fuel pump will not auto-shutoff.

4, AMM 28-22-00-730-801(Engine Fuel Feed Pumps – Functional Test), it requires a minimum fuel of 1000 lb (454 kg)  .

  •  2,000 lbs. is to ensure the fuel pump will not auto-shutoff – Note AMM** will be updated from 1,000 to 2,000 lbs of fuel.(This change is scheduled to be incorporated in the 15-Oct-2024 revision of the 737NG AMM.)
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