1月26日，A320飞机地面双发启动好，机组反映右通气油箱通气口往外漏燃油。分析为当地面使用中央油箱燃油时（因飞行训练，中央油箱方式选择电门当时放人工位），右发FRV在主油箱全满的情况下没有正常关闭，导致右主油箱油过满溢出，参考MEL28-21-02a保留两个中央油箱燃油泵
航后参考TASK28-46-00-810-812测试通气油箱过溢传感器工作正常，对调FLSCU1、2判断故障，并完成空客建议的检查项目。
请问如果中央油箱方式选择电门当时放人工位，出现右主油箱油过满溢出的这种情况是否为操作不当造成？空客的建议如下：
As described in SEEE5-2010-423856, On CFM engines the IDG recirculation is needed on the ground, and therefore there is NO IDG recirculation inhibition on ground. As a result a long taxi, or hold, whilst feeding from the center tank will cause a fuel spillage. Please advise us which manuals include the "NO IDG recirculation inhibition on ground on CFM engines" content. We can not find this descriptions in AMM, AFM and FCOM. Since a long taxi, or hold, is easily happened in flight trainings, in this situation, pilots prefer to use center tank fuel during waiting on ground. So they usually select center tank MODE SEL P/BSW (48QA) to MAN position. Further to the question that has been raised relating to possible causes of the wing spillage, please find below initial synopsis on this issue.BACKGROUND: A320 was found right wing fuel spillage when it was on ground and both engines running.
The aircraft status is that:
1. Left and right wing tanks (inner cell and outer cell) were full of fuel, center tank had certain fuel.
2. Both engines were running;
3. Center tank MODE SEL P/BSW (48QA) was MAN position, all the six fuel pumps P/BSW were ON position.
Note that because long time waiting for ATC take-off order, the pilots set center tank MODE SEL P/BSW (48QA) MAN position with two engine running.
Then the ground staff found right wing fuel spillage.
We think the possible reason of fuel spillage is cause by the fuel recirculation system.
When both engine running, the fuel recirculation for the cooling system (recirculation system)
moves the warm fuel from the IDG cooling system to the wing tank.
Because the wing tanks are full of fuels, and center tank MODE SEL P/BSW (48QA) was in MAN position,
the fuel recirculates to wing tanks and cause fuel spillage.
QUESTION:
1. Please help to confirm if the fuel recirculation system is the root cause of fuel spillage.
2. Is it necessary to take some maintenance actions for the aircraft for the fuel spillage? Except clean the fuel area.
The aircraft is now on the ground. The pilots refuse to take off and ask for maintenance action. So please response ASAP.
ANSWER:As mentioned above, it is likely that the cause of the fuel spillage is due the center tank pumps being ON,
with the manual mode P/BSW selected in MANUAL.
As identified when feeding the engine by the center tank pumps there is a certain quantity of fuel that will recirculates into the wing tanks.
On IAE engines the over flow sensor will turn of the IDG cooling if the surge sensor gets wet,
to help prevent against fuel spillage.
On CFM engines the IDG recirculation is needed on the ground,
and therefore there is NO IDG recirculation inhibition on ground. As a result a long taxi, or hold,
whilst feeding from the center tank will cause a fuel spillage.
Another issue should be noted that this possible outcome is covered in the Operational Procedure for dispatch with the center tank autofeed system inoperative (ref MEL 28-20-
01 Automatic Fuel Feed System), in which it states:If the center tank is not empty apply following procedure,:Before engines start:
FUEL MODE SEL...............................................MAN3 minutes after engine start:
CTR TK PUMP 1 AND 2......................................OFFAfter slats retraction and when fuel in one wing less than 5,000 kg (11,000 lb)CTR TK PUMP 1 AND 2......................................ONWhen CTR TK PUMP LO PR warning illuminates:
CTR TK PUMP 1 AND 2.....................................OFFAs can be seen this clearly states that if operating in manual mode that the center tank pumps are only run for 3 minutes at engine start, and no longer (i.e. replicating the AUTOFEED system).
we suggest that CSZ perform the following a) Transfer fuel from the right wing into the center tank until there is approximately 4,500 kg in the right wing.
(b) Note the fuel quantities in all tanks
(c) With engines OFF, open the crossfeed valve
(d) Make sure that the right wing tank pumps are OFF
(e) Select ON both left wing tank pumps(f) Pressurise the right engine feed line, and confirm that the fuel quantity does not increase by more than 110 kg over 30 minutes (Please also refer to AMM TASK 28-21-00-710-011 - Operational Leak Test of the Air Release Valve Float.)(g) Return aircraft fuel to standard distributionIf in step (f)
there is an increased fuel distribution rate please report further to this office. |
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发表于 2010-1-27 04:40:08
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