[A320] 余压警告系统的OIT

OPERATORS INFORMATION TELEX - OPERATORS INFORMATION TELEX
TO: A330/A340/A340-500/A340-600 Operators
SUBJECT: ATA 52-71 Residual Pressure Warning System
OUR REF: SE 999.0009/12 dated 25 JAN 2012
CLASSIFICATION: INCIDENT
REFERENCES:
AMM 10-12-00 Storage Procedures
AMM 12-21-12-670-804-A Fumigation of the fuselage pressurized areas
AMM 12-31-21-660-801-A Cold Weather Maintenance Air Conditioning
AMM 12-33-00 Pre Conditioning
1. INTRODUCTION
This OIT is to inform operators that the Residual Pressure Warning System (RPWS) is inoperative
when the aircraft is de-powered (aircraft batteries switched off). This function limitation was
discovered during the investigation of a recent event where an A340 was pressurized by an
external air source, whilst it was de-powered during a maintenance procedure. This led to
personnel injury when a cargo door was opened. The event was caused by non-adherence to AMM
procedures, involving the selection of DITCH where the outflow valves remained in the closed
position.
2. MAINTENANCE IMPLICATIONS
Operators are reminded that AMM tasks are designed to preclude the possibility of inadvertent
pressurization of the aircraft during maintenance procedures. Therefore, attention is drawn to the
importance of following AMM procedures strictly, in order to avoid a hazardous aircraft
configuration. If an aircraft door is opened whilst the aircraft is pressurized, the door will open
rapidly and may injure personnel and cause damage to the aircraft. AMM procedures where such
risk may exist if the procedures are not correctly followed include:
AMM 10-12-00 Storage Procedures
AMM 12-21-12-670-804-A Fumigation of the fuselage pressurized areas
AMM 12-31-21-660-801-A Cold Weather Maintenance ?Air Conditioning
AMM 12-33-00 Pre Conditioning
Therefore, even if the RPWS is effective in reducing the risk of personnel injury due to
inadvertent pressurization of the aircraft during ground operation, Airbus would like to draw
operators attention to the below described design limitations of the system.
3. EVENT INVESTIGATION
During the investigation into this event, it has been discovered that the Residual Pressure Warning
System (RPWS) does not provide its warning function when the aircraft is de-powered (aircraft
batteries switched off).
3.1 Intended design function
The RPWS controls the red warning indicators situated at every PAX and cargo doors, which
flash when all of the following conditions are true;
* Engines are NOT running (engines 1 and 2 for A330, engines 2 and 3 for A340)
* PAX door slide NOT armed
* Cabin differential pressure above 2.5 hPa
The RPWS is one function of the Proximity Switch Control Unit (PSCU, FIN 5MJ) which is
powered by aircraft electrical power supplies when the aircraft is operating.
The design intent is that when the aircraft is fully de-powered (aircraft batteries switched off), a
dedicated battery called the Autonomous Standby Power Supply Unit (ASPSU, FIN 101MJ)
should ensure that the RPWS function of the PSCU is maintained. In the event that the RPWS is
triggered, and the associated red door warning lights are illuminated, the ASPSU should maintain
this warning for a nominal 50 minutes, and has a standby time of 4 days.
3.2 Effective function
Despite the above system description, the RPWS is not working when the aircraft is de-powered.
In this condition the PSCU receives the engines running input by default and will not flash the red
warning indicators in the presence of cabin differential pressure.
Therefore, operators attention is drawn to the situation that the RPWS will not provide a warning
(flash the red door lights) as intended if the aircraft is pressurized during a maintenance procedure
where the aircraft is de-powered (aircraft batteries off). However, as long as the aircraft is
powered on its own or by an external power source, the RPWS will provide its warning function.
4. MAINTENANCE RECOMMENDATION
In the scenario where maintenance personnel need to open an aircraft door, but are not sure if the
aircraft is fully depressurized, personnel may attempt to open the avionics bay door (door
reference 811) to ascertain if the aircraft is pressurized or not. The avionics bay door is an inward
opening plug type door. If this door cannot be opened, then the aircraft is pressurized. If this door
can be opened, the aircraft is fully depressurized.
5. FOLLOW-UP
Non-operating RPWS when the aircraft is de-powered is under investigation. More information
will be communicated by update to this OIT by end of April 2012.
Questions about the technical content of this OIT are to be addressed to:
Mr. N.Dadswell, SEEC5,
Phone +33/(0)5.62.11.87.58
Fax +33/(0)5.61.93.44.25
E-mail: nigel.dadswell@airbus.com
Best Regards,
T. ROLLIN
SENIOR VICE PRESIDENT
ENGINEERING AND MAINTENANCE
CUSTOMER SERVICES
AIRBUS S.A.S.
If you do not need to receive OIT any more, or if other people in your organization need to be
added to the distribution, please advise your Airbus Customer Services contact accordingly.
OIT s attachments (if any) can be downloaded from AirbusWorld via AirN@v / Engineering.
客户信息通报
致：A330/A340/A340-500/A340-600 客户
项目：ATA 52-71 余压警告系统
参考号：2012 年1 月25 日SE 999.0009/12
类别：偶然事件
参考：
AMM 10-12-00 Storage Procedures
AMM 12-21-12-670-804-A Fumigation of the fuselage pressurized areas
AMM 12-31-21-660-801-A Cold Weather Maintenance Air Conditioning
AMM 12-33-00 Pre Conditioning
1、简介
本OIT 是向客户通报当飞机整机断电（飞机电瓶关闭）时，飞机余压警告系统不工作的情
况。这个功能限制是在最近A340 飞机维护过程中整机断电时通过外部气源增压时发现，在
开启货舱门时导致了人员受伤。这个事故是由于当DITCH 电门按入时外流活门还处在关闭
位所导致的，在AMM 中没有警告说明。
2、维护操作
在AMM 中已经提醒客户在进行维护工作的过程中可能造成飞机意外不正常增压的情况。因
此，必须严格按照AMM 程序的要求对飞机进行增压，以防止对飞机结构造成损伤。当飞机
增压时，如果打开飞机舱门，此时舱门会迅速打开，并且可能造成人员受伤和飞机结构受损。
如果不按照以下工作程序执行，AMM 程序也可能存在危险：
AMM 10-12-00 Storage Procedures
AMM 12-21-12-670-804-A Fumigation of the fuselage pressurized areas
AMM 12-31-21-660-801-A Cold Weather Maintenance Air Conditioning
AMM 12-33-00 Pre Conditioning
因此，即使余压警告系统可以有效降低飞机在地面维护过程中不正常增压所造成的人员受
伤，但是，还是希望客户能够引起足够的注意以防止由于系统设计缺陷所造成的损伤。
3、事件研究
通过研究发现当飞机整机断电（飞机电瓶关闭）时，余压警告系统不能正常提供其警告功能。
3.1 预期设计功能
余压警告系统控制各个登机门和货舱门的红色警告指示器，当以下所有条件都满足时，红色
警告指示器会闪亮：
* 发动机不工作(A330 飞机的1 和2 发都不工作，A340 飞机的2 和3 发都不工作)
* 登机门滑梯没有预位
* 客舱压差超过250 帕
余压警告系统是临近电门控制组件PSCU（PSCU, FIN 5MJ）的一个功能，当飞机供电时，
PSCU 由飞机电源系统供电。
预期设计是：当飞机整机断电（飞机电瓶关闭）时，一个专用电瓶（自动备用电源供电组件
ASPSU）（ASPSU, FIN 101MJ）确保PSCU 的余压警告系统正常工作。在这个事件中，余压
警告系统工作，并且相应的红色舱门警告灯点亮，ASPSU 保持红色警告信息50 分钟，并且
还有四天的备用时间。
3.2 实际功能
依据上面系统简介，当飞机整机断电时，余压警告系统没有工作。这种条件下，PSCU 获得
错误的发动机运转输入信号，从而导致当客舱压差超过限值时红色警告指示器没有闪亮。
因此，客户需要注意当飞机在整机断电（飞机电瓶关闭）的维护过程中，如果飞机增压，余
压警告系统不会和预期设计功能一样提供警告信息（红色舱门灯闪亮）。
4、维护提示
当维护人员需要开启飞机舱门时，但是不能确定飞机是否已经完全释压，维护人员可以尝试
打开电子舱门（811 舱门）以确定飞机是否增压。电子舱门是一种向内开启的伸缩式门。如
果电子舱门不能打开，表明飞机已经增压。如果电子舱门能够打开，表明飞机已经完全释压。
5、持续跟进
当飞机整机断电时余压警告系统不工作是调查得出的结论，更多的信息将在2012 年4 月OIT
改版时公布。
Questions about the technical content of this OIT are to be addressed to:
Mr. N.Dadswell, SEEC5,
Phone +33/(0)5.62.11.87.58
Fax +33/(0)5.61.93.44.25
E-mail: nigel.dadswell@airbus.com
Best Regards,
T. ROLLIN
SENIOR VICE PRESIDENT
ENGINEERING AND MAINTENANCE
CUSTOMER SERVICES
AIRBUS S.A.S.
If you do not need to receive OIT any more, or if other people in your organization need to be
added to the distribution, please advise your Airbus Customer Services contact accordingly.
OIT s attachments (if any) can be downloaded from AirbusWorld via AirN@v / Engineering.