Question 68 UFIV01 - Chief Engineer - UFIV

The Correct Answer is D **Why option D ("Make an adjustment at the compensating needle valve") is correct:** The symptoms described—cyclic, rhythmic variations in speed at steady load (known as **hunting** or instability)—that immediately stop when the governor is disconnected and the fuel linkage is manually fixed, point directly to a stability issue within the hydraulic governor system itself. This hunting behavior indicates that the governor is overcompensating for speed changes. In a hydraulic governor (such as a Woodward PG or UG type), the compensating system (or temporary droop system) is responsible for damping out these rapid, unwanted oscillations. The compensating needle valve controls the rate of oil flow to and from the compensating dashpot/plunger, thus regulating the timing and magnitude of the temporary feedback signal. If the needle valve is open too wide, the governor is too sensitive, leading to hunting. Closing the compensating needle valve slightly increases the damping and should stabilize the governor, eliminating the cyclic speed variations. **Why the other options are incorrect:** * **A) Tighten the bolts securing the governor base to the engine:** Loose mounting bolts might cause erratic movement or vibration, but they would not typically cause the highly regular, rhythmic hunting behavior that instantly ceases when the governor is manually locked out. Hunting is a dynamic instability inherent to the governor's hydraulic feedback loop. * **B) Replace the governor drive gears:** Worn gears would introduce backlash or timing issues, potentially causing irregular speed fluctuations or noise, but they would not be the primary cause of cyclic hunting instability, which is a characteristic failure of the compensation system. * **C) Replace the fuel injector nozzle of the misfiring cylinder:** A misfiring cylinder (caused by a faulty injector or other issue) would lead to irregular running, excessive smoke, and loss of power, but it would not be the cause of the governor hunting. Crucially, the problem is defined as stopping when the governor linkage is blocked, confirming the issue lies within the governor's control loop, not the engine's combustion process.