After each start or motoring attempt, how long should you wait before the second attempt?

The recommended waiting period of 30 seconds after each start or motoring attempt is essential for several reasons. When an aircraft engine is started or motored, the systems involved generate significant heat. This heat can cause engine components to expand. Allowing a 30-second interval provides an opportunity for the engine to cool down slightly and also allows for fuel and oil to properly circulate. This interval is critical in ensuring that the system does not overheat or damage itself during repeated start attempts, therefore promoting a safe and effective engine start process.

Additionally, this timing aligns with standard operating procedures that are designed to protect both the aircraft and the personnel involved in the operation. By providing a brief waiting period, pilots and crew can also evaluate any indicators of issues that may have occurred during the initial start attempt, enhancing safety and operational efficiency.