A method for monitoring vibration in an engine, comprising: receiving, at a full-authority digital engine control (FADEC) system, a vibration signal from at least one sensor coupled to the engine, characterised in that the method further comprises: receiving, at the FADEC system, a first speed signal representative of an operating speed of a first spool of the engine, and a second speed signal representative of an operating speed of a second spool of the engine; determining, at the FADEC system, a first target frequency of the engine based on the first speed signal, and a second target frequency of the engine based on the second speed signal; altering, at the FADEC system, a center frequency of a first filtering system so that a pass-band of the first filtering system contains the first target frequency, and a center frequency of a second filtering system so that a pass-band of the second filtering system contains the second target frequency; filtering, at the FADEC system, the vibration signal with the first filtering system to obtain a first filtered vibration signal, and the vibration signal with the second filtering system to provide a second filtered vibration signal; determining, at the FADEC system, an amplitude of the first filtered vibration signal and an amplitude of the second filtered vibration signal; comparing the amplitude of the first filtered vibration signal to a first predetermined vibration threshold, and comparing the amplitude of the second filtered vibration signal to a second predetermined vibration threshold; and producing an alert in response to determining that the amplitude of the first filtered vibration signal exceeds the first predetermined vibration threshold, and producing an alert in response to determining that the amplitude of the second filtered vibration signal exceeds the second predetermined vibration threshold, wherein the engine is part of a group of engines operating in collaboration, and the method further comprises reducing an output power of the engine and increasing an output power of the other engines of the group, using the FADEC system, based on the amplitude of the first filtered vibration signal or based on the amplitude of the second filtered vibration signal. receiving, at the FADEC system, a first speed signal representative of an operating speed of a first spool of the engine, and a second speed signal representative of an operating speed of a second spool of the engine; determining, at the FADEC system, a first target frequency of the engine based on the first speed signal, and a second target frequency of the engine based on the second speed signal; altering, at the FADEC system, a center frequency of a first filtering system so that a pass-band of the first filtering system contains the first target frequency, and a center frequency of a second filtering system so that a pass-band of the second filtering system contains the second target frequency; filtering, at the FADEC system, the vibration signal with the first filtering system to obtain a first filtered vibration signal, and the vibration signal with the second filtering system to provide a second filtered vibration signal; determining, at the FADEC system, an amplitude of the first filtered vibration signal and an amplitude of the second filtered vibration signal; comparing the amplitude of the first filtered vibration signal to a first predetermined vibration threshold, and comparing the amplitude of the second filtered vibration signal to a second predetermined vibration threshold; and producing an alert in response to determining that the amplitude of the first filtered vibration signal exceeds the first predetermined vibration threshold, and producing an alert in response to determining that the amplitude of the second filtered vibration signal exceeds the second predetermined vibration threshold, wherein the engine is part of a group of engines operating in collaboration, and the method further comprises reducing an output power of the engine and increasing an output power of the other engines of the group, using the FADEC system, based on the amplitude of the first filtered vibration signal or based on the amplitude of the second filtered vibration signal.