A backup control has been defined for a contemplated variable cycle engine where the primary control is digital electronic. The digital electronic unit controls the many variables so that all the available engine performance is achieved. The backup control provides “get home” ability, smooth transfer action, minimum interference during primary digital control operation, engine overspeed and over-temperature protection and a low power loss failure rate. A hydromechanical approach was selected because of its demonstrated high levels of reliability in main engine controls and to avoid common mode failures such as those induced by lightning and EMI/EMP. Transfer action is initiated upon loss of electrical power, loss of primary control “good health”, overspeed or by pilot action.