自有案例
2024年8月，有1*00飞机出发实时监控警告，出发ENG 2 EEC C1的SMT信息，故障代码为77-43014 | FAN SPEED (N1) SENSOR CHANNEL-A AND CHANNEL-B SIGNALS DO NOT AGREE。
可能性原因
线路检查DJ510B pin1-pin2阻值83.2欧，pin1，pin2对地无穷，DP510B到DP5B，pin1-pin77阻值0.3欧，pin2到pin78阻值0.4欧，都对地绝缘，检查线束正常。
次日航前，发动机启动后控制灯亮，触发信息为73-44634 FAN SPEED (N1) SENSOR LOW TOOTH SIGNAL IS INVALID和77-43024FAN SPEED (N1) SENSOR IS OUT OF RANGE 。
73-44634 FAN SPEED (N1) SENSOR LOW TOOTH SIGNAL IS INVALID
(1)The low tooth signal that indicates fan position has failed.
(2)The low tooth signal amplitude is not sufficiently different from the other tooth signal amplitudes. Selected N1 must be valid and be greater than 34%.
(3)The fault is also set when 67% of single channel N1 sensor data contained noise for more than 90 cumulative seconds and the engine is running at or above idle.
(4)The fault is inhibited if the N1 sensor out of range (77-4302X) or the N1 soft sensor shift fault (77-4301X) is set. The cumulative persistence is latched until an EEC power cycle.
(5)The EEC resets the cumulative noise count after each power cycle, which typically occurs after the engine is shut down. If the EEC power is left on through multiple consecutive flights, normal levels of sensor noise may accumulate enough time to set this fault. It is important to check for indications that the EEC power was left on prior to performing additional fault isolation. Additional fault isolation is not necessary when this fault is set due to power that is accidentally left on.
77-43024FAN SPEED (N1) SENSOR IS OUT OF RANGE
(1)Engine fan speed (N1) signal exceeds valid range (less than 0.00% below idle or 4.36% above idle, or greater than 141.50%) or EEC input circuitry is failed.
(2)The fault will also be set if the engine fan speed (N1) signal on both channels have been invalidated due to exceedance of noise.
测量DP5B pin77-78阻值无穷大（手册标准70-90欧），DP510B pin1-DP5B pin77 阻值0.6欧，DP510B pin2-DP5B pin78阻值0.6欧。DP510B PIN1-PIN2无穷（手册标准70-90欧），判断传感器故障。
在更换N1传感器的过程中，发现发动机侧的SHIM不在位。按手册要求孔探检查内部未发现SHIM的存在。
经核实，sensor安装有两种情况：（1）带shim安装。（2）不带shim安装。原因是让sensor和不同长度孔的发动机适配。 所以依据手册需要先确认当前是否是带shim的构型，核实要求一是看sensor本体再一个是孔探看发动机安装孔内壁。目前现场通过本体检查和孔探均没有看到shim，应该就是不带shim的情况，安装sensor不需要shim适配。
对于N1速度传感器，厂家认为当前装机的这些件号的N1传感器可靠性较差，发布了LEAP-1B-77-00-0006-01A-930A-D对传感器进行改装，厂家认为目前的设计对环境振动具有很高的灵敏度，这会在信号上产生噪声，从而产生EEC故障信息。新件号为VIN 3224KGB00 (P/N 364-044-903-0)
