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[20标准施工] 关于刹车液压保险(PN 2-8041-1)的安装力矩

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东航中国民航大学在线王实名认证人气写手荣誉顾问解疑达人

发表于 2021-6-6 21:42:33 | 显示全部楼层 |阅读模式
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之前的文章:

737NG 刹车液压保险漏油分析及管路力矩


中给出力矩是270磅寸。细心的读者可能已经问题了,文章中只确定了管路的材料,而没有确定液压保险的材料,不是很严谨。


其实,关于这个力矩,之前我也问过波音。



SR
# 3-4831788931 #
DESCRIPTION:
CEA can't find the installation torque of the brake hydraulic fuse(PN 2-8041-1) in normal and alternate brake system when do the ref/A/ and ref/B/ task.We can't identify the materials of fuse body.
Q1. Could Boeing provide the body material information of the PN 2-8041-1 fuse and the installation torque values?
Q2. CEA also needs the body material information of these PN fuses:
2-8020-29
2-8020-6
2-8020-25
2-8020-1
2-8020-27
2-8020-3
2-8020-5
2-7680-1
2-8020-28

RESPONSE:
A1. For part number 2-8041-1 (only):
(a)The material composition of the component includes:
i.Body: 15-5 PH CRES; and
ii.Plug/End Fitting: AMS 4640, AL-NI-BR (Aluminum Nickel Bronze).
(b)Boeing recommends an installation torque value of 270 in-lbs.

A2. The body (only) material information for the following fuse part numbers are:
(a)Aluminum: 2-8020-1, 2-8020-3, 2-8020-5 and 2-8020-6.
(b)Stainless Steel: 2-8020-25, 2-8020-27, 2-8020-28 and 2-8020-29.



细心的朋友可能又看出问题来了,波音的回复里,液压保险接头的材料明明是铝镍青铜合金啊:

ii.Plug/End Fitting: AMS 4640, AL-NI-BR (Aluminum Nickel Bronze).


参考AMM TASK 20-10-51-910-802.Table 210


应该选铝合金的力矩。


铝合金的力矩参考 AMM TASK 20-50-11-910-801. Table 220


对应3/8尺寸管子,力矩应该是170 ±9 in-lb


而如果是钛合金或者不锈钢材料,参考AMM TASK 20-50-11-910-801. Table 221

对应3/8尺寸管子,力矩应该是270 ±14 in-lb


为什么AMS 4640, AL-NI-BR (Aluminum Nickel Bronze)材料,选的是CRES /Titanium 的力矩呢?


于是又问了下厂家,给出的回复如下:


torque of Hydraulic Fuse

To properly respond to China Eastern Airlines' question, as posed in BCS Message CEA-CEA-21-1609-01C, Boeing Engineering conducted additional research and testing on several hydraulic fuses composed of the Al-Ni-Br end fitting material.


Boeing Engineering research concluded that, per AMS 4640, the hardness value for Al-Ni-Br will typically exhibit hardness values much higher than aluminum alloys, but also exhibit hardness well below that of most 15?5 CRES heat treatments (please see below).


6061-T6 Aluminum: ~95 HB

AMS 4640 (Al-Ni-Br):  201-248 HB for material < 2"

Ti-3Al-2.5V Titanium:~290 HB

15-5 (CRES):>300 HB (depending upon HT level)


Thus, Al-Ni-Br alloy is closer to Ti or CRES, although not quite as hard as those materials.


Likewise, from additional sample pass testing at the CRES/Titanium torque value, for Fuse P/N 2-8041-1, Boeing Engineering recommends that, where the 3/8's Al-Ni-Br port connects to CRES or Titanium fittings and hose ends, to use torque value 270 in-lbs (+/-5%).


Note: Boeing is in the process of updating the applicable drawings and reference documentation to assist China Eastern Airlines and other airline Operators to determine installation torque values for hydraulic fuses composed of the Al-Ni-Br end fitting material.

厂家回复是由于AMS 4640, AL-NI-BR (Aluminum Nickel Bronze)材料材料的硬度要远高于6061-T6铝合金,虽然比不锈钢和钛合金低,但是已经很接近,所以选用的是不锈钢钛合金的力矩值。


典型案例分享:


某737NG飞机短停检查发现左主轮舱有液压油渗漏,打泵增压未发现渗漏点。操作舵面、反推均未发现渗漏。


后建议维修人员,分别单开A/B系统EMDP,来回踩下和松开刹车检查,发现正常刹车液压保险漏油:


位手柄丢失:


后在轮舱找到断裂掉落的手柄螺杆:


为防止螺钉断裂导致复位手柄丢失,波音737NG-FTD-32-13003建议液压保险每次送检/修理都更换手柄固定螺钉。







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