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View of the holes at the location of the pyrotechnic igniter bosses on the interior of the nozzle extension.

Although the igniters were intended to ignite the gases between the inner and outer walls of the nozzle extension and were not intended to enter the main combustion chamber's exhaust flow, there are these holes on the interior wall. Perhaps these holes are a backup to the igniters' function: Should the igniters fail, some of the main combustion gases might enter the void between the inner and outer walls of the nozzle extension at this site to ignite the turbine exhaust gas.