导读： 现象及历史　　近期737NG飞机多次反映发动机关车后，在尾喷管内部下方聚集一滩滑油，尤其短尾喷构型的飞机，会从TRF（后涡轮框架）的6点钟位置余油口不断往外滴油，处理导致航班延误。原理分析　　CFM56-7B发动机滑油系统有前后两个集油槽（见图一），前集油槽位于风扇框架的腔体内，后集油槽位于后涡轮框...

现象及历史

　　近期737NG飞机多次反映发动机关车后，在尾喷管内部下方聚集一滩滑油，尤其短尾喷构型的飞机，会从TRF（后涡轮框架）的6点钟位置余油口不断往外滴油，处理导致航班延误。

原理分析

　　CFM56-7B发动机滑油系统有前后两个集油槽（见图一），前集油槽位于风扇框架的腔体内，后集油槽位于后涡轮框架腔体内。前后集油槽都是通过蓖齿气动封严（见图二）保证滑油不外漏。而蓖齿气动封严原理是发动机引气压力大于滑油压力从而保证滑油在油路内部流通不外漏；当发动机引气压力不足时（关车时），油压大于气压，蓖齿气动封严失效，滑油将会从封严的排放口流入后涡轮框架腔体内，并通过后涡轮框架与尾喷的法兰盘缝隙中流出，会在尾喷处留下一滩滑油（新短尾喷构型在后涡轮框架6点钟位置加装了一个排放口，余油也会从此排出，见图三）。

　　新旧尾喷构型在关车后都会从尾喷处漏滑油，此为正常现象，只是新短尾喷构型让余油更容易被看见（见图四）。

　　具体余油轨迹请见图五，其他瓦力棋牌官网详细描述见附件737NG-FTD-79-14001。

　　

　　

　　

　　

　　

排故提示

　　1、如过站机组反映尾喷内漏滑油，现场确认漏油情况，如符合以上描述，计算滑油消耗率，如在以下标准范围内，无需处理，与机组做好原理解释。

　　参考AMM71-00-00-800-806-F00 ENGINE OPERATION LIMITS：

　　1） 正常滑油消耗率低于0.4US quart/hour或者0.1US gallon/hour(0.38 liters/hour)；（机务有滑耗监控机制，如高于0.4，会有相应的分析核实或进一步的排故检查纠正措施）

　　2） 出现以下情况之一时，必须参考FIM找出原因（监控分析核实，主要航后排故使用，不是放行标准）。

　　a. 滑油消耗率平稳增加

　　b. 滑油消耗率徒增

　　c. 滑油消耗率大于0.8US quart/hour或者大于0.2US gallon/hour(0.76 liters/hour)

　　3） 图表：最大允许滑油消耗率（放行标准，第2段落答本的依据）：

　　Model 737-

　　Winglet installed

　　Oil consumption guideline US gal/hr(liter/hr)

700

No

Yes

0.29(1.1098)

0.25 (0.946)

800

No

Yes

0.33(1.249)

0.31(1.173)

900

No

Yes

0.34(1.287)

0.33(1.249)

　　注：1USgallon=4USquart

　　注：A、计算滑油消耗率时，时间最好用发动机实际的运行时间，尽量不要用飞行小时。（发动机运行时间可电话咨询技术支援）

　　B、因发动机滑油量在驾驶舱指示是1进制，指示精度较低，如加滑油后驾驶舱指示19，但可能实际油量并未到19，而只是18点几。所以在实际运行中，如飞行一两个小时左右，关车稳定后，驾驶舱指示可能只有18甚至17，为正常指示现象，计算时可将大概误差减掉。

　　2、如机组写FLB，可参考以下格式统一答本,乐游棋牌官方网站并放行：

　　参考737NG-FTD-79-14001该处关车后漏滑油为正常现象，该发的滑油消耗率为？US quart/hour，参考AMM71-00-00-800-806-F00在手册标准？US quart/hour范围内。

　　IT IS NORMAL THAT THE OIL LEAKING IN THE EXHAUST NOZZLE REF 737NG-FTD-79-14001.

　　THE CONSUMPTION OF OIL IS ? quart/hour. WITHIN THE LIMITS OF ？US quart/hour REF AMM71-00-00-800-806-F00.

故障原因

结论（MCC）

　　CFM56-7B关车后，尾喷内集聚一滩滑油或从TRF6点钟余油口处漏滑油属于正常现象

　　备注：只希望对故障的处理思路和方法有所启发，目的在于交流，只作为参考，不作为故障处理的标准。

737NG-FTD-79-14001

　　ATA:

　　7900C00

　　Last Revised:

　　03-DEC-2014

　　Issue Title:

　　Oil Puddles in CMF56-7B Exhaust Nozzle

　　Originated:

　　03-DEC-2014

　　Airplane Model:

　　737NG

　　Minor Model(s):

　　Other Models:

　　no other models applied to issue

　　ECD:

　　Illustrations:

　　Oil Pooling in Exhaust Nozzle

　　References:

　　Issue Status:

　　Closed

　　Deion

　　Some 737NG operators have reported finding oil puddles in the exhaust nozzle during routine visual inspections. The purpose of this FTD article is to explain why the CFM56-7B engine exhibits oil in the exhaust system and inform that maintenance action is generally not required for oil in the exhaust system. A presentation on this subject, from the June 2014 CFM56-7B WTT Meeting, is attached to this FTD Article.

　　Background

　　Oil leakage from the rear turbine bearing compartment through the center vent tube and aft sump drain is normal for all CFM56-7B engines. The center vent tube evacuates air from the engine sumps and this air carries a small amount of oil. The aft sump drain can drain oil into the exhaust plug during engine motoring and during engine shutdown. During engine motoring, oil supply pressure increases faster than the aft sump air pressure. This causes in a momentary differential pressure that results a small amount of oil to pass over the aft sump rotating seal. The differential pressure can also occur during engine shutdown.

　　Oil from the center vent tube and aft sump drain can settle at the bottom of the exhaust plug. From there, the oil can seep through the flange, where the exhaust plug attaches to the turbine rear frame, and onto the exhaust nozzle.

　　Status

　　AMM 71-71-00 (Engine Vents and Drains) contains the following note:

　　An oil puddle in the exhaust system is usual. After engine dry or wet motoring, a large oil puddle in the exhaust system is usual. Oil leaks are possible at the turbine rear frame (TRF) and primary exhaust system flange. It is permitted to see oil drops at the TRF drain port at the 6:00 o’clock location.

　　There is no maintenance action required for oil puddles in the exhaust nozzle as long as oil consumption is within normal limits.

　　Interim Action

　　None

　　Final Action

　　There is no maintenance action required for oil puddles in the exhaust nozzle as long as oil consumption is within normal limits. If an operator suspects that the oil puddles may be more than normal, then we recommend looking at the oil consumption data from the operator normal oil consumption monitoring program. If the oil consumption is beyond normal limits per Section 9 of the Maintenance Planning Data (MPD) or AMM 71-00-00/201, Boeing recommends troubleshooting per FIM 79-05 Task 801, engine Oil Consumption is High (Oil Quantity Decreases at a Quick Rate).

　　Parts List:

　　No Parts Applied

　　Related Categories:

　　In Service Occurrences

　　Technical Focus Item

　　;font-size:12.0000pt;" >S quart/hour REF AMM71-00-00-800-806-F00.

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