Originally Posted by
AAKEE
The RTM322 is sensitive to spool bending after a time intervall of shut down.
Usually needs Engine vent procedure before another engine start to spread the temperatures.
If not done, it could lead to engine stagnation during engine start due to the compressor blades rubbing the housing. In the extreme case, later brake down in flight due to the damage.
There is at least one or two cases known of this happening.
Uncontained, as in releasing engine parts via the exhaust, yes thats probable.
Originally Posted by
RickNRoll
It sounds like the spool bending I made a post about.
If the enginge was shut down for >10 minutes but less than 3hrs a vent prodecure should be performed before the engine start.
If the vent procedure is not performed when needed, the bent engine shaft could cause rubbing between compressor blades and the housing, causing damage.
There is at least a few examples of this since before, causing the engine to seize. Without mention a specific nation, it has happened that the engine vent procedure was “forgotten” or something like that, causing engine failure in the flight that followed that engine start with no vent.
The software change was implemented in my Air force, progressively combined with retrofit to FOC.
After booting the helicopter a software function decided if engine vent is needed, if so a “HOT” flag is shown at the engine/or engines that need to be ventilated.
The software reminds the pilot that engine vent is needed (theres also a semi automatic built in help), and also shortens the 3h window for when it is actually needed.
Regardless of this any engine start need to be carefully looked for stagnation in the N1 below 50%, and there time limits for having the N1 not increasing as it should.