During DEC/EDECU lockout, which engine protection feature remains active?

During DEC/EDECU lockout, which engine protection feature remains active?

• A. NP Overspeed Protection
• B. TGT Limiting Disabled
• C. Oil Pressure Monitoring Disabled
• D. Fuel Flow Unregulated

Answer: (A)

During DEC/EDECU lockout, the engine’s electronic protections are bypassed, but the NP overspeed protection stays active because it’s a hardware safeguard tied to the power turbine’s maximum speed. If Np tries to exceed its limit, this protection will intervene to prevent turbine damage, even when the DEC/EDECU is locked out. The other protections—TGT limiting, oil pressure monitoring, and fuel flow control—are disabled under lockout, so they do not automatically intervene. This is why NP overspeed protection is the active safeguard in that condition.

During DEC/EDECU lockout, the engine’s electronic protections are bypassed, but the NP overspeed protection stays active because it’s a hardware safeguard tied to the power turbine’s maximum speed. If Np tries to exceed its limit, this protection will intervene to prevent turbine damage, even when the DEC/EDECU is locked out. The other protections—TGT limiting, oil pressure monitoring, and fuel flow control—are disabled under lockout, so they do not automatically intervene. This is why NP overspeed protection is the active safeguard in that condition.