Which statement about the Hobbs timer activation is correct?

Which statement about the Hobbs timer activation is correct?

• A. Oil temperature triggers the Hobbs timer.
• B. Total engine hours trigger the Hobbs timer.
• C. Oil pressure decreases triggers the Hobbs timer.
• D. Oil pressure is sensed by the Hobbs indicator.

Answer: (D)

The Hobbs timer is driven by the engine’s oil pressure switch. It begins counting when oil pressure is present (engine running) and stops when oil pressure drops to zero (engine off or pressure lost). It isn’t triggered by oil temperature or by total engine hours. So the Hobbs indicator uses the oil pressure signal to control the timer, which is why sensing oil pressure is the correct concept.

The Hobbs timer is driven by the engine’s oil pressure switch. It begins counting when oil pressure is present (engine running) and stops when oil pressure drops to zero (engine off or pressure lost). It isn’t triggered by oil temperature or by total engine hours. So the Hobbs indicator uses the oil pressure signal to control the timer, which is why sensing oil pressure is the correct concept.