Final answer:
Permitted single engine operation at idle with a gust lock usually involves a control lock that doesn't engage the engine controls or can be disengaged while the aircraft is stationary, allowing engine idling. The Aircraft's Flight Manual or Pilot's Operating Handbook should always be consulted for specific procedures.
Step-by-step explanation:
The question relates to the operation of an aircraft, particularly in regards to the gust lock system which is used to secure an aircraft's control surfaces while it is parked to prevent damage from wind gusts. In general, the operation of a single engine at idle is permitted with a type of gust lock that is designed to allow such operation. Specifically, this would be a control lock that either does not engage the engine controls or can be disengaged while the aircraft is stationary, allowing engine idling without risking movement of the control surfaces.
It is important to note that each aircraft may have specific procedures regarding the use of gust locks and engine operations, so it is essential to consult the Aircraft's Flight Manual (AFM) or the Pilot's Operating Handbook (POH) for the particular aircraft being operated. Improper use of gust locks can lead to safety issues or damage to the aircraft.