Hung Start v's Hot Start
Angels 60. A hung start is where the engine "bogs down", or if you prefer, stagnates at a RPM below idle. It may be that a compressor unloading valve has failed closed and the engine cannot accelerate past the RPM at which it stagnates. This may or may not be above starter cut-out speed. A hot start can happen at any phase of the start cycle and does not have to be accompanied by a stagnation in engine RPM. In the case of either a hung start or a hot start the action required is the same. Shut down and either try again or, if a hot start has been allowed to exceed limits, inspect the hot end for any damage i.e. via a borescope inspection.