FROM: THE BOEING COMPANY
TO: Shandong Airlines (SHG)
[MESSAGE NUMBER:SHG-SHG-25-0862-03B] Boeing Response
MESSAGE DATE: 24-Dec-2025 08:40 (GMT-08:00) Pacific Standard Time (America/Los_Angeles) / 24-Dec-2025 16:40 (GMT)
================================================================================
问题描述：
在起飞滑跑过程中，如果中央油箱燃油量低于 453 kg（1000 lb），是否有可能出现相应中央油箱燃油泵低压灯（LOW PRESSURE）亮起，并随后触发主警戒（MASTER CAUTION）信号？此外，当中央油箱燃油量低于该阈值时，飞机的起飞构型逻辑或某个特定的抑制功能，是否会抑制与中央油箱燃油泵低压相关的主警戒/警告提示？
回复：
是的，如果中央油箱燃油量低于 453 kg，在起飞滑跑过程中，由于油箱内燃油移动，相关中央油箱燃油泵低压灯有可能亮起。然而，主警戒灯（MASTER CAUTION）与燃油系统指示灯的亮起，需要燃油泵持续产生低压，并且 LOW PRESSURE 灯持续稳定亮 10 秒或更长时间。在起飞阶段，这一条件可能发生，也可能不发生。因此，是否触发主警戒信号，取决于当时情况。
飞机的起飞构型逻辑中，并不包含在中央油箱燃油量低于该阈值时，抑制与中央油箱燃油泵低压相关主警戒的抑制功能。同时，也没有专门设计用于抑制与中央油箱燃油泵低压相关主警戒的特定抑制功能。
中央油箱燃油泵低压引起主警戒的逻辑如下：
当两个中央油箱燃油泵电门均在 ON 位，并且两台泵都持续产生低压时，如果两个 LOW PRESSURE 灯持续稳定亮 10 秒或更长时间，则会亮起 MASTER CAUTION 以及 Fuel System Annunciator 指示灯。
当一台中央油箱燃油泵选择 OFF，而另一台泵持续产生低压时，如果该泵的 LOW PRESSURE 灯持续稳定亮 10 秒或更长时间，同样会亮起 MASTER CAUTION 和 Fuel System Annunciator 指示灯。
设定这一 10 秒延时的目的是，为了防止在最低燃油量条件下，由于加速（如起飞）或减速导致的不必要主警戒显示。
在进行再现（RECALL）时，若一侧 LOW PRESSURE 灯稳定亮，则在 RECALL 时 Fuel System Annunciator 指示灯会亮起。
中央油箱燃油泵必须存在持续低压（导致 LOW PRESSURE 灯稳定亮），持续 10 秒或更长时间，才会亮起 MASTER CAUTION 和 Fuel System Annunciator 指示灯。
如果中央油箱燃油泵仅发生瞬时低压（LOW PRESSURE 灯闪烁、不稳定），则不会触发主警戒系统信号。
中央油箱燃油泵低压探测，基于燃油泵入口未被燃油完全覆盖，从而导致泵入口吸入空气（汽蚀），引起中央油箱燃油泵出口压力降低。
不存在一个明确的中央油箱燃油量数值可以与汽蚀发生直接对应。
泵入口暴露可能由于：
— 起飞加速
— 持续转弯
— 爬升/下降姿态变化
— 飞机倾斜
— 地面机头下俯姿态
在不同燃油量情况下都可能发生（运营中观察到：燃油量低至 0 kg 以及高至 500 kg 时均有发生低压指示的情况）。
只要 LOW PRESSURE 灯稳定亮 10 秒或以上，在任何飞行阶段都可能触发 MASTER CAUTION，包括起飞阶段。
QRH 中没有更多额外信息，其目的主要是为机组提供处理步骤。
以下为 FCOM 燃油系统描述节选：
Fuel Pumps
每个油箱配有两台交流电驱动燃油泵，燃油在通过泵体时提供冷却与润滑。中央油箱燃油泵输出压力高于主油箱燃油泵，以确保在所有燃油泵工作情况下，优先使用中央油箱燃油。
每台泵由独立压力传感器监控。当某个泵的传感器检测到低输出压力后，该中央油箱燃油泵将在一个短暂延时后自动关闭。
注：当燃油量较低，且飞机处于爬升、下降或地面机头下俯姿态时，燃油泵 LOW PRESSURE 灯可能闪烁。
注：当燃油量较低，中央油箱燃油泵 LOW PRESSURE 灯在巡航中也可能闪烁。由于飞机姿态和泵入口位置存在微小差异，可能一侧比另一侧更早出现低压。
当中央油箱燃油量显示为 0 时，仍可能出现低压指示。
低压灯闪烁可持续长达 5 分钟，然后 Fuel System Annunciator 指示灯与 MASTER CAUTION 才会亮起。
以下为 AFM 摘录：
当中央油箱燃油少于 5,000 lb（2,300 kg），且飞机已准备好开始滑行：
中央油箱燃油泵必须置于 OFF。
当中央油箱燃油量在爬升和巡航阶段接近约 1,000 lb（500 kg）时：
两个中央油箱燃油泵开关必须置于 OFF。
在下降与着陆阶段，当中央油箱燃油量接近约 3,000 lb（1,400 kg）时：
两个中央油箱燃油泵开关必须置于 OFF。
在首次出现燃油泵低压指示时：
必须将燃油泵立即置于 OFF。
如果在巡航阶段中央油箱燃油量大于 1,000 lb（500 kg），可再次将中央油箱燃油泵置于 ON。
当中央油箱为空时：
两个中央油箱燃油泵必须置于 OFF。
设置中央油箱燃油泵为 OFF 的原因，是为了避免因飞机姿态变化而导致燃油泵入口失去燃油覆盖。
This message is sent to the following:
Shandong Airlines
PRIORITY: Routine
ACCOUNT: Shandong Airlines (SHG)
DUE DATE: No Action Required
FIELD BASE: BFSTNA-Jinan-China
PRODUCT TYPE: Flight Operations
PRODUCT LINE: 737
PRODUCT: 16 - Flight Crew Procedures (QRH, FCOM Vol 1, FCTM, ECL)
ATA: 0200 Operations - General
SERVICE CATEGORY: Operations & Customer Support
SUBJECT: fuel pump
REFERENCES:
/A/ SHG-SHG-25-0862-01C
DESCRIPTION:
During the takeoff roll, if the center tank fuel quantity is below 453 kg (1000 lbs), is it possible for the respective fuel pump low pressure light to illuminate and subsequently trigger the master caution system signal? Furthermore, does the aircraft's takeoff configuration logic or a specific inhibit function suppress the master caution/warning associated with the center tank pump low pressure when the fuel quantity is below this threshold?
RESPONSE:
Yes, if the center tank fuel quantity is below 453 kg it is possible that the respective center tank pump low pressure light will illuminate during take-off roll due to fuel movement within the tank. However, illumination of the MASTER CAUTION and Fuel System Annunciator lights requires that the pump is producing continuous low pressure for 10 seconds or more. This requirement may or may not occur during takeoff. Therefore, triggering the MASTER CAUTION signal may or may not occur during takeoff.
The aircraft’s takeoff configuration logic does not contain an inhibit function that suppresses the MASTER CAUTION associated with the center tank pump low pressure light when the fuel quantity is below this threshold. Also, there is no specific inhibit function designed to suppress the MASTER CAUTION associated with the center tank pump low pressure light when the fuel quantity is below this threshold.
The logic for MASTER CAUTION due to center tank fuel pump low pressure is as follows:
With both center tank pump switches ON and both pumps producing continuous low pressure, the steady illumination of both LOW PRESSURE lights for 10 seconds or more will illuminate the MASTER CAUTION and Fuel System Annunciator lights. With one center tank fuel pump switched OFF and the opposite pump producing continuous low pressure, the steady illumination of the opposite center tank fuel pump LOW PRESSURE light for 10 seconds or more will illuminate the MASTER CAUTION and Fuel System Annunciator lights. This 10-second time delay is necessary in order to guard against nuisance display of the MASTER CAUTION indication during operations with acceleration (such as takeoff) or deceleration with minimum fuel in the tank.
When doing a recall of existing fault annunciations, the steady illumination of one LOW PRESSURE light will cause the Fuel System Annunciator light to illuminate upon recall.
There must be a sustained low pressure condition in a center tank fuel pump (resulting in a steady illumination of a LOW PRESSURE light) for 10 seconds or more for the MASTER CAUTION and Fuel System Annunciator lights to illuminate. A momentary low pressure condition in a center tank pump (resulting in a flickering, unsteady illumination of the LOW PRESSURE light) will not trigger the Master Caution system signal.
There is no definitive system logic that will inhibit the center tank low pressure indications during takeoff. The takeoff configuration logic will not inhibit the center tank low pressure indications during takeoff.
Center fuel pump low pressure detection is based on the pump inlet not fully covered by fuel, leading to cavitation (air ingestion at the pump inlet), resulting in low center tank fuel pump pressure. There is no definitive fuel quantity in the center fuel tank that is related to when cavitation occurs. Uncovering the pump inlet may happen as a result of acceleration forces (such as during takeoff or during a sustained turn) or changes in airplane attitude (such as changes in pitch during a climb or descent, or airplane bank angle, or a nose-down attitude when on the ground). Uncovering the pump inlet may occur with varying quantities of fuel in the center tank. (Operators have observed fuel quantities as low as 0 kg and as high as 500 kg when the LOW PRESSURE light illuminates). MASTER CAUTION activation occurs when there is steady illumination of a LOW PRESSURE light for 10 seconds or more in any flight phase. This may occur during takeoff.
There is no additional information provided by the QRH. Its purpose is to provide the flight crew with steps to correct the situation.
The following is from the FCOM Fuel System description:
Fuel Pumps
Each fuel tank uses two AC powered fuel pumps which are cooled and lubricated by fuel passing through the pump. Center tank pumps produce higher pressure than main tank pumps. This ensures that center tank fuel is used before main tank fuel, even though all fuel pumps are operating. Individual pressure sensors monitor the output pressure of each pump. Each center tank pump will automatically shut off, after a short delay, when that pump’s sensor detects low output pressure.
Note: Fuel pump LOW PRESSURE lights may flicker when tank quantity is low and the airplane is in a climb, descent, or on the ground with a nose-down attitude.
Note: Center tank fuel pump LOW PRESSURE lights may flicker when tank quantity is low and the airplane is in cruise. One pump may indicate low pressure sooner than the other due to aircraft attitude and/or slight variation between pump inlet position. Low pressure indication may occur after center tank quantity reads zero. Low pressure light flickering can continue for as long as 5 minutes before the Fuel System Annunciator light and the Master Caution lights are illuminated for the associated center tank pump.
Below is an extract quoted from the AFM:
The center tank fuel pumps must be OFF for takeoff if center tank fuel is less than 5,000 pounds (2,300 kilograms) with the airplane readied for initial taxi.
Both center tank fuel pump switches must be selected OFF when center tank fuel quantity reaches approximately 1,000 pounds (500 kilograms) during climb and cruise or 3,000 pounds (1,400 kilograms) during descent and landing. The fuel pumps must be positioned OFF at the first indication of fuel pump low pressure.
The center tank pumps may be positioned ON again when established in cruise flight if the center tank contains more than 1,000 pounds (500 kilograms) of fuel. Both center tank pump switches must be positioned OFF if the center tank is empty.
The reason for setting the center tank fuel pumps to OFF is to avoid the pump inlets losing fuel coverage due to aircraft movement.
If attachments are referred to and are not present, please access them by logging into the Boeing Communication System on MyBoeingFleet or contact your Boeing Field Service Representative.
Flight Operations Engineering (FLOE)
Customer Support
The Boeing Company
BCA Operations Centers 24 Hour Contact Numbers
787: +1 (206) 544-7787
All Other Models: +1 (206) 544-7500
评论 (0)